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<HTML> <HEAD><TITLE>The nearest stars</TITLE> <style> h1 {color:#F2A20B;} h2 {color:#F2A20B;} h3 {color:#F2A20B;} h4 {color:#9C8900;} h5 {color:#9C8900;} h6 {color:#9C8900;} td {color:#9C8900;} </style> </HEAD> <BODY BGCOLOR="#F2EED1"> <h1>The nearest stars: a conworlder's guide</h1> As a resource for aspiring sf writers, here's a handy list of the stars nearer than 10 parsecs, with real estate appraisals. You'll recognize many of them, as we've known where the good stars are for decades and they've been used many times by various writers. <p>You can get most of this at Wikipedia (<a href="http://en.wikipedia.org/wiki/List_of_nearest_stars">here</a> and <a href="http://en.wikipedia.org/wiki/List_of_nearest_bright_stars">here</a>), also <a href="http://www.solstation.com/stars.htm">at SolStation</a>; but I've tried to concentrate on information useful for conworlding. I've left out historical observations, chemistry, and location in the sky (use the maps instead). If your main planet orbits one of these stars, you should of course look up more information on it. <p>You can see what I made of it myself on <a href="incatena.html">my Incatena page</a>. More <a href="/resources/pck.html">conworlding resources here</a>. <hr> <table> <tr> <td colspan="2"> <i>Click the <a name="map">map</a> to enlarge</i> </td><td rowspan="2"> <a href="NearStars.gif"><img src="NearStars.gif" width="645" height="314"></a> </td> </tr> <tr> <td> <p><b><a href="#General">General info</a></b> <br><a href="#Where">Where to put colonies</a> <br><a href="#Mag">Magnitude</a></h3> <br><a href="#Long">For long-range thinkers</a> <br><a href="#Names">Star names</a> <br><a href="#Exo">Known extrasolar planets</a> <br><a href="#Dist">Distances between stars</a> <br><a href="#Meas">Measurements and caveats</a> <br><a href="#Color">Color</a> </td><td> <p><b><a href="#Near">Within five parsecs</a></b> <br><a href="#Reds">Red dwarfs</a> <br><a href="#brown">Brown dwarfs</a> <p><b><a href="#Lt10">Out to 10 parsecs</a></b> <br><a href="#Further">Further out</a> </td></tr> </table> <hr> <h2><a name="General">General info</a></h2> <h3><a name="Where">Where to put colonies</a></h3> The <i>Astronomy & Geology</i> chapter of the <a href="pck.html"><i>Planet Construction Kit</i></a> gives more information on stellar types and habitable zones, as well as how to set up your planet once you've got it. <p>Stars vary immensely in <b>brightness</b>. Our sun is pretty near the top of the list in our local neighborhood. It's a <b>G</b> star, and that's the cachet of quality in the list below: stars like the sun are likely to have sunlike solar systems. We can guess that K is almost as good— it's dimmer, but you just put your planet closer. <p>With brighter stars, the problem is that they're young. A stars (such as Sirius) are likely to last only some hundreds of millions of years; even F stars (such as Procyon) may last just two billion. Compare the 4 billion years it took for Earth to develop an interesting ecosphere, and the 4.6 billion years it took to develop intelligent life. <p>B stars are even brighter, but they're also moot for our purposes; the closest one is Regulus at 78 ly. <p>Super-bright, super-massive O stars seem likely to blow away the proto-planetary dust by photoevaporation. But the closet one is ζ Ophiuchi which is a bit of a trek, 460 ly. <p>The red dwarfs, class M, have their own problem: it's likely that the habitable zone is so close that planets would be tidally locked, and that would probably destroy the atmosphere. Violent stellar flares could be a problem too. For this reason I've listed but de-emphasized the M stars. (One clever solution: make your earthlike planet a moon of a gas giant. It'd be tidally locked to its planet, but not to the sun.) <p>Also worrisome are the many <b>multiple star systems</b>. This could make planetary orbits unstable, and recall we'd like billions of years of stability. If the stars are relatively far apart (50+ AU), it may not be a problem. <p>Not everyone needs a planet, of course. My Incatena dudes are as happy to live on a space habitat as a planet. <h3><a name="Mag">Magnitude</a></h3> Magnitude is just brightness. The system goes back to Ptolemy at least, who divided the stars into six magnitudes. It was regularized in the 19C as a logarithmic scale: 5 magnitudes of difference = 100 times brighter. Thus if A is one magnitude <i>lower</i> than B, it's 2.512 times brighter. (<i>Higher magnitudes are dimmer.</i>) <p><b>Apparent</b> magnitude is measured from Earth... a very parochial measurement, of course, once we're flitting about in space, and we'll have none of it here, except to offer a table that can help get the concept across: <table> <tr><td>-27</td> <td>Sun as seen from Earth</td></tr> <tr><td>-23</td> <td>Sun as seen from Jupiter</td></tr> <tr><td>-13</td> <td>maximum brightness of full moon</td></tr> <tr><td>-4.9</td> <td>maximum brightness of Venus</td></tr> <tr><td>-2.9</td> <td>maximum brightness of Jupiter and also Mars</td></tr> <tr><td>-1.47</td> <td>Sirius</td></tr> <tr><td>-.04</td> <td>Arcturus</td></tr> <tr><td>-.27</td> <td>our friend α Centauri</td></tr> <tr><td>1.25</td> <td>Deneb</td></tr> <tr><td>1.97</td> <td>Polaris (the northern pole star)</td></tr> <tr><td>3.5</td> <td>τ Ceti</td></tr> <tr><td>5.32</td> <td>Uranus </td></tr> <tr><td>6.5</td> <td>limit of naked eye visibility under excellent conditions</td></tr> <tr><td>6.73</td> <td>Ceres, the largest asteroid</td></tr> <tr><td>9.5</td> <td>limit of visibility using 7x50 binoculars</td></tr> <tr><td>31.5</td> <td>limit of the Hubble telescope</td></tr> </table> <p>More interesting is <b>absolute magnitude</b>, which allows comparisons regardless of distance. For stars it's what the apparent magnitude would be if the star was 10 parsecs (32.6 ly) away. So stars closer than that— i.e. the stars on this page— have an absolute magnitude smaller than their apparent one. The sun's is a not very impressive 4.83; but then the red dwarfs that make up most of its neighbors are 11 or more. <blockquote><img src="Magnitudes.gif"></blockquote> The diagram suggests differences in magnitude. (Unfortunately I can't make the whites brighter than your screen, so I've had to just add more pixels.) <p>The typical star is a red dwarf; our sun is in the top 10% for luminosity. But the scale extends much, much higher. The brightest star presently known is R136a1, a blue hypergiant in the Large Magellanic Cloud, with an absolute magnitude of -12.5. (That is, if it were one parsec away it'd be as bright as the full moon.) Even that's not the limit— e.g the quasar 3C 273 has an absolute magnitude of -26.7... that is, at one parsec it'd be as bright as the sun. You might not want to get any closer; quasars are the hungry accretion disks around the massive black holes at the center of large young galaxies. <h3><a name="Long">For long-range thinkers</a></h3> If your story is set thousands of years in the future, be aware that all these stars are moving. Ross 248, for instance, has a radial velocity of 81 km/s, which is .027% of lightspeed. Over thousands of years, that adds up: Ross 248 is expected to approach to just 3.0 ly from the Sun by AD 38,000. It's probably fair to say that most stars listed here will be no more than 0.2 ly away from their current position in the next millennium. You'll want to keep an eye on that Barnard's Star, the star with the highest proper motion; it's heading our way and in AD 11,700 will be just 3.8 ly away. Disappointingly, it won't even be visible in the sky then. <p>If you <i>really</i> like to think ahead, you probably want a red dwarf: it's estimated that a dwarf of 0.1 solar mass can keep burning for 10 trillion years (compare our sun which will have a lifetime of 10 billion years, and it's half over). <h3><a name="Names">Star names</a></h3> Hundreds of stars have beautiful names, mostly Greek, Latin, or Arabic. And very few of those are on this list, becuase the brightest stars in the sky are mostly giants very far from Sol. <p>So what you get are names from one star catalog or another. The Greek letter + constellation names, which cover most visible stars, derive from Johann Bayer's <i>Uranometria</i>, published in 1603. The Greek letters are (somewhat roughly) assigned by brightness; some constellations are large enough that Bayer ran out of Greek letters and started using Roman letters. <p>John Flamsteed's 1712 catalog used numbers plus constellation name, e.g. 61 Cygni; these are used in the absence of a Bayer designation. <p>Wilhelm Gliese published a list of nearby stars (1969), which are often more convenient than previous in-depth catalogs— e.g. Gliese 581 is preferred to BD-07° 4003 (from the 19th century <i>Bonner Duchmusterung</i>). Gliese expanded the catalog in 1979 working with Hartmut Jahreiß, which accounts for the GJ names below. <p>"Wolf" is Max Wolf, who published a list of stars with high proper motion in 1919; "Ross" is Frank Ross, who found hundreds more such stars. Naturally, stars with high proper motion (i.e. that move quickly across the sky) are likely to be nearby. A few stars are named for their discoverer, and again this was largely due to their high proper motion. <p>It's hard to believe that colonists would actually call their sun "Omicron Two Eridani", so you might think about how they'd rename it. <h3><a name="Exo">Known extrasolar planets</a></h3> This is something new and exciting: in the last fifteen years we've been detecting actual extrasolar planets, more than a thousand by now. Only a few have been imaged, in the infrared; mostly they're detected by observing tiny discrepancies in the star's radial velocity (movement toward or away from us), which itself is observed from the spectral lines in the star's spectogram. A fair number have also been found by transits— i.e. by the temporary dimming of the star when the planet passes in front of it. <p>Both methods are skewed toward finding gas giants in very close orbits— hot Jovians. They orbit at closer than 0.5 AU and as close as 0.015 AU, and are tidally locked; compare Jupiter's 5.2 AU. They're believed to have formed farther away and migrated to their present position; intriguingly, this process may not prevent formation of a terrestrial planet in the habitable zone later, and indeed may make it more water-rich due to the gas giant dragging in material from the outer system. <p>All but 50 of the known exoplanets have a mass at least 10 times that of the Earth, and many outmass Jupiter. (Jupiter's mass is 318 times Earth's.) Many of them, surprisingly, have high orbital eccentricity, and this is also bad news for stable orbits for terrestrial planets. <p>I've noted stars with known exoplanets, but at this point it's not really possible to detect terrestrial planets in the habitable zone... which is good news for the sf writer as you can plonk them where you like. <p>The sf convention has been to number planets outward from the sun with Roman numerals— e.g. τ Ceti IV. This however is only suitable if you know all the planets; astronomers presently number exoplanets in order of discovery, with lowercase letters starting with b— e.g. τ Ceti b. Again, once people are living in the system they're going to rename them. <h3><a name="Dist">Distances between stars</a></h3> Distances to Sol are given below, but how do you find distances between other stars? The fastest way is to ask <a href="http://www.wolframalpha.com/">WolframAlpha</a>. For instance, paste in <tt>from Epsilon Eridani to Procyon</tt> and you'll get 11.47 ly. <h3><a name="Meas">Measurements and caveats</a></h3> <b>Mass and luminosity</b> are reported as compared to the sun. E.g. a mass of 1.1 means that the star is 1.1 times as massive as the sun. <p><b>Years</b> always refers to Earth years, and an <b>AU</b> is an astronomical unit, the distance from the Earth to the sun. <b>Ly</b> are of course light-years. <p>A rough-and-ready formula for the <b>habitable zone</b> is to take the square root of the luminosity, and take 95% of this figure as the inner limit and 137% as the outer limit. Where I've provided a figure, however, it's from the neckbeards at SolStation. <p>Binary stars often have very <b>eccentric orbits</b>, so average separation is misleading. I've provided the range where it's available. <img src="Solarfreq.gif" align="right"> <h3><a name="Color">Color</a></h3> <p>The diagram shows the sun's radiation emission by wavelength. It emits most of its light in the visible spectrium... this is no coincidence; of course animals evolved to make use of the most abundant frequencies. The peak is in the green area, but the overall light is white. The sun's disk looks yellow to red in the sky due to atmospheric scattering. <p>Other stars have different emission spectra. A and B stars peak in the ultraviolet; M stars peak in the infrared. We classify them, however, according to their emission of visible light. To the eye, a (sufficiently bright) A star is white to bluish white; F is white; G is yellowish white; K is yellow-orange, and M is orange-red. The traditional color descriptions are exaggerated. <p>The middle number of the spectral class is a detailed classification— e.g. the sun's G2 means it's 0.2 along the G portion of the temperature scale— it's a fairly hot G star. The last portion gives the luminosity class; most of the stars here are V for main sequence, and a few are IV for subgiants. There are a couple of VI subdwarfs. <p>  <h2><a name="Near">Within five parsecs</a></h2> These 46 systems are found in a sphere of 523 cubic parsecs. <br>  <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="ACent">α Centauri</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 149px; top: 103px"><font color="black">• α CENTAURI</a></div> <div style="position: absolute; left: 304px; top: 15px"><font color="black">+</a></div> </div></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">4.37 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G2V  </td> <td>K1V  </td> <td>M5.5Ve</td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>4.38</td><td>5.71</td> <td>15.49</td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.1</td><td>1.52</td> <td>.12</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>1.52</td><td>.91</td> <td>.0017</td></tr> </table> <br>Also known as Rigil Kentaurus (from Arabic <i>Rijl Qanṭūris</i> 'tail of the centaur') α Centauri is the third brightest star in our sky and dear to sf fans as it's the closest system. As it's far south in our sky, many sf fans have never seen it. The Chinese name is <i>Nán Mén Èr</i> (second star of the southern gate). <p>It's a triple system. A is much like the sun but slightly larger and brighter; B is smaller. A and B have an orbital period of 80 years, and vary between 11 and 36 AU. That's a little close for comfort. The habitable zone is calculated at ~ 1.25 AU for A, 0.7 AU for B; not much farther out, orbits may be unstable. No planets have yet been detected. <p>From a planet orbiting A, B would move through the sky in the course of its own year, with an increment due to the 80-year AB revolution. B would appear from -18 to -21 absolute magnitude, much dimmer than we see our sun (-26.7) but much brighter than the moon (-12.5). <p>A red dwarf, Proxima Centauri, orbits the pair .21 ly (15000 AU) away with a period of over 100,000 years; as it's presently closer to us it's the closest star, though really if you're planning a trip to Proxima you'd might as well take the time to visit the primary. It's so dim that it'd only be fifth magnitude from the vicinity of A. <p>From α Centauri, the sun would have an apparent magnitude of 0.5, about like Betelguese or Procyon from Earth. If you want to make this calculation for any star, use the formula <p><i>4.8 + 5 * ((log10 (<b>d</b>/3.26))-1)</i> <p>where <b>d</b> is the distance in ly. To calculate for other stars, replace the sun's absolute magnitude 4.8 with the star's. <p>From α Centauri, our sun would appear near the W of Cassiopeia, indicated with a + on the mini-map. To find the sun's location from other stars, check the <a href="#map">map</a>: reverse the declination (e.g. α Centauri's -61° becomes +61°) and add 12 hours to the right ascension (e.g. α Centauri's 14h39m becomes 2h39m). <br>  <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td colspan="3" width="200"><h3><a name="Sirius">Sirius</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 253px; top: 70px"><font color="black">• SIRIUS</a></div> </div></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="2">8.58 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>A1V  </td> <td>DA2</td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>1.42</td><td>11.34</td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>2.02</td><td>.98</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>25.4</td><td>.026</td></tr> </table> <br>Sirius is the brightest star in the sky; though it's a respectable A star, it's mostly just really close. (Compare, say, Deneb, an A2 Ia star with an absolute magnitude of -7.0, 2200 times brighter than Sirius, but 1400 ly away.) Its Arabic name is <i>aš-Ši`rā</i>; the Chinese call it <i>Tiānláng</i> 'sky wolf', the Persians <i>Tir</i>, the Hebrews <i>Sihor</i>. <p>Sirius has a tiny white dwarf companion— half the mass of the primary, but the size of the Earth. White dwarfs are more or less dead stars, the carbon-oxygen residue of a red giant, with no more fusion, just a glow provided by heat. (However, B is brighter than A in X-rays.) The two stars take 50 years to orbit each other, ranging from 8 to 31 AU apart, which would probably make planetary orbits unstable (and indeed no planets are known in the system). <p>Worse news for colonists: the system is just 200 to 300 million years old, far too little for any planet to develop an ecosphere. (Plus B was a red giant as recently as 120 million years ago.) <br>  <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td colspan="2" width="200"><h3><a name="EEri">ε Eridani</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 296px; top: 66px"><font color="black">• ε ERIDANI</a></div> </div></td></tr> <tr bgcolor="#6E1203"><td>Distance</td> <td>10.52 ly  </td></tr> <tr bgcolor="#6E1203"><td>Type</td> <td>K2V</td></tr> <tr bgcolor="#6E1203"><td>Abs Magn </td><td>6.19</td></tr> <tr bgcolor="#6E1203"><td>Mass </td><td>.82</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.34</td></tr> </table> <br>ε Eridani is under a billion years old, so no planets with ecospheres are likely. However, it's the closest star with a (fairly likely) known planet: a Jupiter-sized gas giant about 3.4 AU from the star. This and the planet's high orbital eccentricity probably are not good news for terrestrial planets in the habitable zone (at .5 to 1 AU). <p>Perhaps more interesting, the system seems to have two asteroid belts, one at 3 AU and one at 20 AU. <br>  <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td colspan="3" width="200"><h3><a name="Procyon ">Procyon </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 242px; top: 59px"><font color="black">• PROCYON</a></div> </div></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="2">11.41 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>F5V-IV  </td> <td>DA</td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>2.66</td><td>12.98</td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.42</td><td>.602</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>7.73</td><td>.00055</td></tr> </table> Procyon has a white dwarf companion, ranging from 8.9 to 21 AU away and orbiting in 41 years. This may make orbits unstable in the habitable zone around at about 2.7 AU; also, the system is only about 3 billion years old. <p>It's name is Greek for 'before the dog', as it rises before Sirius. The Mandarin name is <i>nánhésān</i> 'southern river #3'. <p>Luyten's Star is just 1.11 ly away. <br>  <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td colspan="3" width="200"><h3><a name="61Cyg">61 Cygni</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 63px; top: 30px"><font color="black">• 61 CYGNI</a></div> </div></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="2">11.36 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K5.0V  </td> <td>K7.0V</td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>7.49</td><td>8.31</td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.70</td><td>.63</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.215</td><td>.15</td></tr> </table> <br>61 Cygni is a double system of two cozy K stars, separated by 44 to 124 AU and orbiting in 659 years. That's far enough apart that terrestrial planets should have no problems; the habitable zone for A is at about 0.46 AU. In addition the system is around six billion years old, so the system is our first good candidate for an ecosphere. <p>The system is known for its high proper motion. It'll be just 9 ly away in AD 20,000 and thereafter will recede again. <br>  <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="Eindi">ε Indi</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 51px; top: 102px"><font color="black">• ε INDI</a></div> </div></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">11.82 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K5Ve  </td> <td>T1.0V  </td> <td>T6.0Ve</td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.89</td><td>25+</td> <td>25+</td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.762</td><td>-</td> <td>-</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.22</td><td>-</td> <td>-</td></tr> </table> <br>ε Indi is a promising K star, with a habitable zone around .61 AU. The system is about six billon years old, plenty of time for an ecosphere to form. <p>The star is orbited by a pair of <a href="#brown">brown dwarfs</a> at about 1450 AUs, themselves separated by about 2 AU. The biggest of them is 40 to 60 times the mass of Jupiter. <br>  <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td colspan="2" width="200"><h3><a name="TCeti">τ Ceti</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 320px; top: 70px"><font color="black">• τ CETI</a></div> </div></td></tr> <tr bgcolor="#6E1203"><td>Distance</td> <td>11.9 ly  </td></tr> <tr bgcolor="#6E1203"><td>Type</td> <td>G8Vp</td></tr> <tr bgcolor="#6E1203"><td>Abs Magn </td><td>5.68</td></tr> <tr bgcolor="#6E1203"><td>Mass </td><td>.78</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.52</td></tr> </table> <br>τ Ceti is a single G star, so you should feel at home already. It's probably 6 billion years old; its habitable zone is roughly at .7 AU. <p>It has an unusually large cloud of asteroids and comets— more than ten time the mass of the sun's. This may mean a much higher level of bombardment than in our system. <p>It has a fairly awful traditional name, Durre Menthor, from Arabic <i>al-durr' al-manthūr</i> 'the scattered pearls of the broken necklace'. Its Mandarin name is <i>Tiāncāng wǔ</i> 'Sky granary #5'. <br>  <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td colspan="2" width="200"><h3><a name="G1618">Groombridge 1618 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 210px; top: 23px"><font color="black">• GROOMBRIDGE 1618 </a></div> </div></td></tr> <tr bgcolor="#6E1203"><td>Distance</td> <td>15.85 ly  </td></tr> <tr bgcolor="#6E1203"><td>Type</td> <td>K7.0V</td></tr> <tr bgcolor="#6E1203"><td>Abs Magn </td><td>8.16</td></tr> <tr bgcolor="#6E1203"><td>Mass </td><td>.67</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.046</td></tr> </table> <br>As Groombridge 1618 is fast-rotating and subject to flares, it may be relatively young, a billion years old or so. The flares, comparatively much larger than the sun's, could make close planets a bit uncomfortable. <br>  <h3><a name="Reds">Red dwarfs</a></h3> Has anyone named one of these Trumpkin? <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td><i>Name</i></td> <td><i>Distance   </i></td> <td><i>Type</i></td> <td><i>Abs Magn</i></td> </tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Barnard's Star</font></td> <td>5.96 ly</td> <td>M4.0Ve</td> <td>13.22</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Wolf 359</td> <td>7.78 ly</td> <td>M6.0V </td> <td> 16.55</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Lalande 21185</td> <td>8.29 ly</td> <td>M2.0V</td> <td>10.44</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Luyten 726-8</td> <td>8.73 ly</td> <td>M5.5Ve / M6.0Ve</td> <td>15.40 / 15.85</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Ross 154</td> <td>9.68 ly</td> <td>M3.5Ve</td> <td>13.07</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Ross 248</td> <td>10.32 ly</td> <td>M5.5Ve</td> <td>14.79</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Lacaille 9352</td> <td>10.42 ly</td> <td>M1.5Ve</td> <td>9.75</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Ross 128</td> <td>10.92 ly</td> <td>M4.0Vn</td> <td>13.51</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">EZ Aquarii</td> <td>11.27 ly</td> <td>M5.0Ve / M / M</td> <td>15.64 / 15.58 / 16.34</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Struve 2398</td> <td>11.52 ly</td> <td>M3.0V / M3.5V</td> <td>11.16 / 11.95</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Groombridge 34</td> <td>11.62 ly</td> <td>M1.5V / M3.5V</td> <td>10.32 / 13.30</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">DX Cancri</td> <td>11.83 ly</td> <td>M6.5Ve </td> <td>16.98</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">GJ 1061</td> <td>11.99 ly</td> <td>M5.5V</td> <td>15.26</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">YZ Ceti</td> <td>12.13 ly</td> <td>M4.5V</td> <td>14.17</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Luyten's Star</td> <td>12.37 ly</td> <td>M3.5Vn</td> <td>11.97</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Teegarden's star</td> <td>12.51 ly</td> <td>M6.5V</td> <td>17.22</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">SCR 1845-6357</td> <td>12.57 ly</td> <td>M8.5V / T6</td> <td>19.41 / ?</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Kapteyn's Star</td> <td>12.78 ly</td> <td>M1.5V</td> <td>10.87</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Lacaille 8760</td> <td>12.87 ly</td> <td>M0.0V</td> <td>8.69</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Kruger 60</td> <td>13.15 ly</td> <td>M3.0V / M4.0V</td> <td>11.76 / 13.38</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Ross 614</td> <td>13.35 ly</td> <td>M4.5V / M5.5V</td> <td>13.09/ 16.17</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Wolf 1061</td> <td>13.82 ly</td> <td>M3.0V</td> <td>11.93</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Van Maanen's star</td> <td>14.07 ly</td> <td>MD27</td> <td>14.21</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Gliese 1</td> <td>14.23 ly</td> <td>M3.0V</td> <td>10.35</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Wolf 424</td> <td>14.31 ly</td> <td>M5.5V / M7Ve</td> <td>14.97 / 14.96</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">TZ Arietis</td> <td>14.51 ly</td> <td>M4.5V</td> <td>14.03</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">GJ 687</td> <td>14.79 ly</td> <td>M3.0V</td> <td>10.89</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">LHS 292</td> <td>14.81 ly</td> <td>M6.5V</td> <td>17.32</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">GJ 674</td> <td>14.81 ly</td> <td>M3.0V</td> <td>11.09</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">GJ 1245</td> <td>14.81 ly</td> <td>M5.5V / M6.0V / M5.5</td> <td>15.17 / 15.72 / 18.46</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">GJ 440</td> <td>15.06 ly</td> <td>DQ6</td> <td>13.18</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">GJ 1002</td> <td>15.31 ly</td> <td>M5.5V</td> <td>15.40</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">Gliese 876</td> <td>15.34 ly</td> <td>M3.5V</td> <td>11.81</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">LHS 288</td> <td>15.61 ly</td> <td>M5.5V</td> <td>15.51</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">GJ 412</td> <td>15.83 ly</td> <td>M1.0V / M5.5V</td> <td>10.34 / 16.05</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">AD Leonis</td> <td>15.94 ly</td> <td>M3.0V</td> <td>10.87</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">GJ 832</td> <td>16.09 ly</td> <td>M3.0V</td> <td>10.20</td></tr> </table> <h3><a name="brown">Brown dwarfs</a></a></h3> I've listed these separately, as they're arguably not stars at all, but overgrown, independent gas giants. They're too small to sustain hydrogen fusion, so they don't emit significant heat or visible light. However, they can have planets of their own. <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td><i>Name</i></td> <td><i>Distance   </i></td> <td><i>Type</i></td> <td><i>Abs Magn</i></td> </tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">WISE 1541-2250</td> <td>9.4 ly </td> <td> Y </td> <td> 21.2</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">UGPS J072227.51-054031.2</td> <td>13 ly</td> <td>T10</td> <td>16.52</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">DEN 1048-3956</td> <td>13.17 ly</td> <td>M8.5V </td> <td> 19.37</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">WISE J1741+2553</td> <td>15 ly</td> <td>T8</td> <td>14</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">LP 944-020</td> <td>16.20 ly</td> <td>M9.0V</td> <td>20.02</td></tr> <tr bgcolor="#6E1203"><td><font color="#F2A20B">DEN 0255-4700</td> <td>16.20 ly</td> <td>L7.5V</td> <td>24.44</td></tr> </table> <h2><a name="Lt10">Out to 10 parsecs</a></h2> A sphere of 20 parsecs has a volume of 4189 cubic parsecs, so this tranche contains about 320 systems, the vast majority of them uninteresting red dwarfs. So I'll just give some information about the brighter stars. <table border=0 cellspacing="0" cellpadding="0"> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="o2Eri">ο<sup>2</sup> Eridani</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 285px; top: 66px"><font color="black">• ο<sup>2</sup> ERIDANI</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> ο<sup>2</sup> Eridani is a promising system, with a habitable zone around .7 AU. <p>White dwarf B and red dwarf C orbit each other a comfortable 400 AU away from A (and 35 AU from each other); from A they'd be a bright -8 and -6 magnitude, several times brighter than Venus. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">16.45 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K1Ve  </td> <td>DA4  </td> <td>M4.5eV</td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.92</td><td>11.01</td> <td>12.66</td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.84</td><td>.50</td> <td>.20</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.46</td><td>.013</td> <td>.008</td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="70Oph">70 Ophiuchi</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 106px; top: 58px"><font color="black">• 70 OPHIUCHI</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> A binary system, with a separation of 11.4 to 35 AUs. The habitable zone would be about .66 AU. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">16.6 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K1Ve</td> <td>K5Ve  </td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.71</td><td>7.48</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.92</td><td>.70</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.43</td><td>.08</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="Altair">Altair</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 82px; top: 50px"><font color="black">• ALTAIR</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> Altair has such a high rotation rate (1/4 day) that it's noticeably squashed: its equatorial diameter is 20% higher than its polar diameter. <p>Again, A stars are usually young, so probably no ecospheres here. <p>Its Chinese name is <i>Qiānniú xīng</i> 'cowherd star'. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">16.8 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>A7IV-V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>2.21</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.79</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>10.6</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="SDra">σ Draconis</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 85px; top: 10px"><font color="black">• σ DRACONIS</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> σ Draconis has a beautiful traditional name, Alsafi. It's a nice old star, ready for your aliens or colonists to move in. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">18.8 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G9V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.87</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.87</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.43</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G570">Gliese 570</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 145px; top: 73px"><font color="black">• GLIESE 570</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> Also known as 33 G. Librae. The primary is orbited at a comfortable distance of 190 AU by a pair of red dwarfs, less than 1 AU apart. If that weren't enough, there's a brown dwarf 1500 AU out. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">19.2 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K4V  </td> <td>M1V  </td> <td>M3V</td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.79</td><td>~ 11</td> <td>11.05</td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.80</td><td>.55</td> <td>.35</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.16</td><td>.02</td> <td>.003</td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="eCas">η Cassiopeiae</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 333px; top: 20px"><font color="black">•</a></div> <div style="position: absolute; left: 210px; top: 17px"><font color="black">η CASSIOPEIAE</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> η Cassiopeiae is a binary system; the stars orbit from 36 to 107 AU apart. A's habitable zone is estimated to run from .9 to 1.8 AU. It has a traditional name of Achird. Strangely, A is smaller than Sol but more luminious. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">24.6 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G0V  </td> <td>K7V</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>4.59</td><td>8.64</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.95</td><td>.62</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>1.29</td><td>.06</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="36Oph">36 Ophiuchi</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 115px; top: 76px"><font color="black">• 36 OPHIUCHI</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> The two very similar primaries have a very eccentric mutual orbit, ranging from 7 to 169 AU. The habitable zone round either star would be about .5 to 1.0 AU. This is probably a young system, under 2 billion years. <p>In addition there's an orange-red dwarf about 5000 AU away— .08 ly. Personally I'd put my planet there, at .5 AU, where the wacky central stars won't destabilize it. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">19.5 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K0V  </td> <td>K1V  </td> <td>K5V</td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.29</td><td>5.33</td> <td>6.34</td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.85</td><td>.85</td> <td>.71</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.28</td><td>.27</td> <td>.09</td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="36Oph">Gliese 783</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 77px; top: 85px"><font color="black">• GLIESE 783 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> Gliese 783, or J. Herschel 5173, is a binary system; average separation is 43 AU. It's likely to be more than six billion years old. A's habitable zone is from .46 to .90 AU. <p>It's zipping toward us and will be 6.7 ly away in 40,000 years. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">19.62 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K2V  </td> <td>M3.5V  </td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.40</td><td>12.6</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.82</td><td>.20</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.23</td><td>.000077</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="36Oph">82 G. Eridani</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 297px; top: 92px"><font color="black">• 82 G. ERIDANI</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> 82 G. Eridani is a quite sunlike star, at least six billion years old. The habitable zone would be from .56 to 1.1 AU. <p>There's a very recent (Aug 2011) report that no less than three big terrestrial planets orbit very close to the star, all at less than 0.25 AU (closer than Mercury is to the sun) and all between 2.4 and 4.8 Earths in mass. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">19.77 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G8V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.35</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.97</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.62</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="36Oph">δ Pavonis</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 79px; top: 108px"><font color="black">• δ PAVONIS</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> δ Pavonis is about the size of the sun, is a single star, and at least six billion years old, so it's a good candidate for planets with ecospheres. Not for terribly long, perhaps; it may be at the subgiant phase, exhausting its hydrogen before starting on the helium and becoming a red giant. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">19.92 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G8IV</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>4.62</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.991</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>1.18</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">Gliese 892 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 38px; top: 16px"><font color="black">• GLIESE 892 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> No extra info here, but there's no showstoppers at least. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">21.3 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K3V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.50</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.81</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.21</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">ξ Boötis </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 145px; top: 45px"><font color="black">• ξ BOÖTIS</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> ξ Boötis is a binary system. Its chromospheric activity may peg it as an infant star (60 million years old), but the lack of a dust disk suggests an age of at least a billion years. A's luminosity varies by about 3% in a ten-day cycle. <p>The two stars are separated by 16.5 to 51 AU. There are reports that B may have a companion several times the mass of Jupiter. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">21.9 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G8Ve  </td> <td>K4Ve</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.54</td> <td>7.81</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.9</td><td>.7</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.49</td><td>.061</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">Gliese 667 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 117px; top: 85px"><font color="black">• GLIESE 667</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> The two, rather similar main stars have a very eccentric orbit, separated from 5 to 20 AU— not considered good for stable planets. A red dwarf orbits the pair between 56 and 215 AU. <p>There's a large terrestrial planet closely orbiting C at a mere 0.05 AU, with at least 5.7 times the mass of the Earth. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">22.7 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K3V  </td> <td>K5V  </td> <td>M2V</td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>7.07</td> <td>8.02</td> <td>11.03</td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.75</td><td>.65</td> <td>.38</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.13</td><td>.05</td> <td>.003</td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">β Hydri </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 336px; top: 116px"><font color="black">•</a></div> <div style="position: absolute; left: 260px; top: 116px"><font color="black">β HYDRI </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> β Hydri is the closest bright star to the south celestial pole— though it's still 12° distant. It's likely to be over 6 billion years, and it may be a subgiant (heading for the red giant phase). <p>It may have a gas giant of about four times Jupiter's mass. <p>The habitable zone would be at around 1.9 AU. I'd just like to note that this is where I placed <a href="http://www.zompist.com/mars/planets.html#Okura">Okura</a>. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">24.4 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G2IV</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>3.43</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.1</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>3.53</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">107 Piscium </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 320px; top: 46px"><font color="black">•</a></div> <div style="position: absolute; left: 260px; top: 46px"><font color="black">107 PISCIUM</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> 107 Piscium is a bit dimmer than the sun, about six billion years old. The habitable zone would be around .62 AU. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">24.4 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K1V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.87</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.83</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.46</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">μ Cassiopeiae</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 330px; top: 26px"><font color="black">•</a></div> <div style="position: absolute; left: 260px; top: 26px"><font color="black">μ CASSIOPEIAE</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> The two components are separated by 3.3 to 12 AU. <p>μ Cassiopeiae shares the name Marfak with θ Cassiopeiae which is in almost the same location in our sky; but since θ is 137 ly away, I say screw it and use the nice name for μ. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">24.6 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G5VIp</td> <td>M5V</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.78</td><td>11.6</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.60</td><td>.17</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.46</td><td>.001</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="TWpis">TW Piscis Austrini</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 40px; top: 80px"><font color="black">• TW PISCIS AUSTRINI</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> TW Piscis Austrini varies in luminosity by about 1% in a ten-day cycle, and is also subject to dramatic flares. <p>It's only a light year from Fomalhaut. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">24.9 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K5Vp</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>7.07</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.725</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.12</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="Fomalhaut ">Fomalhaut </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 41px; top: 80px"><font color="black">• FOMALHAUT </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> Fomalhaut is a bright A star, only a few hundred million years old. Its name is from Arabic <i>fam al-ħūt</i> 'mouth of the fish'; the Mandarin name is <i>běi luò shī mén</i> 'northern military gate'. <p>Fomalhaut has one of the few exoplanets which has been detected visually, a gas giant with a mass of 0.5 to 2 times that of Jupiter, orbiting at 133 AU, lying just within a massive dust belt. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">25 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>A3V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>1.73</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>2.1</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>17.7</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">Gliese 673 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 112px; top: 60px"><font color="black">• GLIESE 673 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> No exciting facts. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">25.2 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K5-7V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>7.65</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.7</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>?</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="Vega">Vega </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 100px; top: 30px"><font color="black">• VEGA</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> Vega is the brightest star (in absolute terms) on our list. It's about half a billion years old, and rotating so quickly that it's squashed; the equatorial diameter is 23% larger than the polar. It's moving closer and in 210,000 years it'll be the brightest star in the sky. It was the northern pole star around 12000 BC and will be again in 12000 years. <p>The name derives from Arabic <i>wāqi`</i> 'falling [vulture]'; the Chinese name is <i>Zhī nǚ</i> 'weaver girl', and the Hindu name is <i>Abhijit</i>. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">25.3 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>A0V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>.58</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>2.135</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>37</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="pOri">π<sup>3</sup> Orionis </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 280px; top: 52px"><font color="black">• π<sup>3</sup> ORIONIS</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> π<sup>3</sup> Orionis is larger than the sun, and has the traditional name Tabit. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">26.2 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>F6V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>3.65</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.236</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>3</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="sDraco">χ Draconis </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 100px; top: 6px"><font color="black">• χ DRACONIS</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> χ Draconis is a binary system, about 8 billion years old, with a separation of just .6 to 1.4 AU. The habitable zone is unfortunately unstable for planets. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">24.4 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>F7 Vvar</td> <td>K0V</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>4.16</td><td>?</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.03</td><td>.75</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>1.86</td><td>.29</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">Gliese 884 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 40px; top: 73px"><font color="black">• GLIESE 884 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> With its low luminosity, Gliese 884's habitable zone would be centered at around .2 AU. One observatory has classed it as M1 instead. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">26.6 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K7+Vk</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>8.34</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.62</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.04</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">p Eridani</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 320px; top: 102px"><font color="black">•</a></div> <div style="position: absolute; left: 230px; top: 102px"><font color="black">p ERIDANI</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> p Eridani is a double star, with a separation of 30 to 98 AU, which is probably enough to allow either of these stars to have a terrestrial planet. <p>I placed my planet <a href="/mars/planets.html#maraille">Maraille</a> here. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">26.3 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K2V</td> <td>K3V</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.25</td><td>6.35</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.88</td><td>.86</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.28</td><td>.25</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">ζ Ursae Majoris</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 194px; top: 37px"><font color="black">• ζ URSAE MAJORIS</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> ζ Ursae Majoris is quite a system: the two primary stars, both very sunlike, are separated by 12.5 to 40 AU, and each seems to have a very dim red dwarf companion. A is separated from Ab by .8 to 2.6 AU, while B is separated from Bb by just .06 AU. The system has the traditional name Alula Australis. The companions are not good news for terrestrial planets. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">27.3 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G0Ve</td> <td>G5Ve</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>4.71</td><td>5.23</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.05</td><td>.90</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>1.1</td><td>.67</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">Chara </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 177px; top: 30px"><font color="black">• CHARA </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> Chara (or β Canum Venaticorum) is like a slightly larger sun, and is considered an excellent candidate for life. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">27.4 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G0V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>4.65</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.025</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>1.15</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">μ Herculis </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 109px; top: 38px"><font color="black">• μ HERCULIS </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> μ Herculis is a multiple system. B and C are a pair of red dwarfs separated by 9.4 to 13.5 AU, and these in turn are separated from A by about 286 AU. A also seems to have a dwarf companion at about 17 AU. <p>A's habitable zone is optimum for a planet at about 1.6 AU— but it seems to be heating up into a subgiant phase, which suggests that any planet which developed life is now toast. A great place for a sentient species to have changed planets... </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">24.4 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G5IV</td> <td>M3.5V</td> <td>M4V</td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>3.80</td><td>10.73</td> <td>11.18</td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.1</td><td>.31</td> <td>.31</td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>2.4</td><td>.005</td> <td>.003</td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">61 Virginis</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 165px; top: 75px"><font color="black">• 61 VIRGINIS</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> 61 Virginis is quite sunlike, and no less than three supersized terrestrial panets have been reported: a 5-Earther at .05 AU and two 20+-Earthers (i.e. Neptune-sized) at .22 and .48 AU. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">27.8 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G5V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.07</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.95</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.85</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">ζ Tucanae </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 338px; top: 100px"><font color="black">•</a></div> <div style="position: absolute; left: 230px; top: 100px"><font color="black">ζ TUCANAE </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> ζ Tucanae is slightly larger than the sun, and is estimated at 3 billion years old. <p>I placed <a href="/mars/planets.html#NewBharat">New Bharat</a> here. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">28 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>F9.5V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>4.56</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.99</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>1.3</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">χ<sup>1</sup> Orionis </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 262px; top: 45px"><font color="black">• χ<sup>1</sup> ORIONIS </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> χ<sup>1</sup> Orionis is quite sunlike, but its dwarf companion at 3.5 to 9.3 AU is liable to mess up orbits for terrestrial planets. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">28.3 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G0V</td> <td>M6</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>4.67</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1</td><td>.15</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>1.08</td><td>?</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">Gliese 250</a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 250px; top: 63px"><font color="black">• GLIESE 250</a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> Gliese 250 is a binary system, with a relatively large separation averaging 500 AU. The habitable zone for A centers around .4 AU, about the distance of Mercury (which is not tidally locked, but rotates very slowly). </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">28.4 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K3V</td> <td>M2.5</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.88</td><td>?</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.80</td><td>.50</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.15</td><td>.00058</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">41 G. Arae </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 115px; top: 92px"><font color="black">• 41 G. ARAE </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> 41 G. Arae is a binary star; its red dwarf companion is in a highly eccentric orbit averaging at least 100 AU. A's habitable zone would be centered around .64 AU. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">28.7 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G8V</td> <td>K7Vp</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.28</td><td>?</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.81</td><td>?</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.42</td><td>?</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">HR 1614 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 277px; top: 63px"><font color="black">• HR 1614 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> HR 1614 is a spectroscopic binary, which generally means that the two stars are too close to be visually distinguished. We don't seem to have much info on the companion. The system is about two billion years old. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">28.4 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K3V</td> <td>?</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.49</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.845</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.21</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">HR 7722 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 76px; top: 80px"><font color="black">• HR 7722 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> HR 7722, also known as Gliese 875, is about 8 billion years old, and its habitable zone is at about .6 AU. <p>Two planets have been detected, both more than 20 Earths in mass (i.e. Neptune-sized)— one at .32 AU and one at 1.2 AU. Interestingly, the outer planet's orbit intersects the habitable zone... perhaps its satellites are habitable. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">28.8 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K0Vv</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.0</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.78</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.35</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">γ Leporis </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 268px; top: 74px"><font color="black">• γ LEPORIS </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> γ Leporis A is a bit brighter than the sun, probably about 3 billion years old. Its habitable zone would center around 1.6 AU. Its companion is about 860 AU distant. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">29.3 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>F6V</td> <td>K2V</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>3.83</td><td>?</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.23</td><td>.63</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>2.6</td><td>.25</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">δ Eridani </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 294px; top: 68px"><font color="black">• δ ERIDANI </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> δ Eridani is also known as Rana, the Frog. It's about 8 billion years old, but it is now fusing helium on its way to red giant status. This would be bad news for any planet that grew an ecosphere during its Main Sequence eons, but good news for a planet in the present habitable zone centered at 1.7 AU. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">29.5 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K0IV</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>3.75</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.2</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>2.8</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">Groombridge 1830 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 184px; top: 40px"><font color="black">• GROOMBRIDGE 1830 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> Groombridge 1830 is smaller than the sun, but seems to be subject to superflares millions of times greater than our sun's flares. Dress accordingly— light cottons and knits. The star seems to be a halo star, ten billion years old; because it's not moving with the rotating disk of the galaxy it has a huge proper motion. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">29.9 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G8Vp</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.62</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.66</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.19</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">β Comae Berenices </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 166px; top: 40px"><font color="black">• β COMAE BERENICES </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> β Comae Berenices is a bit brighter than the sun, and is perhaps 4 billion years old. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">29.8 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G0V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>4.45</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>1.15</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>1.42</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">κ<sup>1</sup> Ceti </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 298px; top: 58px"><font color="black">• κ<sup>1</sup> CETI </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> κ<sup>1</sup> Ceti is a little dimmer than the sun, and seems to be young— under a billion years— and subject to superflares. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">29.8 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G5Vv</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.03</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.9</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.85</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">γ Pavonis </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 60px; top: 104px"><font color="black">• γ PAVONIS </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> γ Pavonis is a little brighter (but smaller) than the sun, and may be over 9 billion years old. Its habitable zone would center around 1.2 AU. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">30.1 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>F6V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>4.4</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.8</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>1.5</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">HR 4523 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 189px; top: 88px"><font color="black">• HR 4523 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> HR 4523 A has the same stellar class as the sun, and is at least as old, both good characteristics for planets with ecospheres. It has a red dwarf companion currently 211 AU away. <p>It has a Neptune-like planet (16 times Earth's mass) at about .46 AU, while its habitable zone would be centered at 1.1 AU. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">30.1 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G2V</td> <td>M4V</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.06</td><td>?</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.89</td><td>.07</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.00007</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">61 Ursae Majoris </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 187px; top: 35px"><font color="black">• 61 URSAE MAJORIS </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> 61 Ursae Majoris is a young star, probably about a billion years old. It's a good candidate for planets but not ecospheres. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">31.1 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>G8V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.41</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.85</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.66</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">HR 4458 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 191px; top: 80px"><font color="black">• HR 4458 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> HR 4458 is a binary system, with an average separation of 80 AU. A's habitable zone centers around .56 AU. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">31.1 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K0V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>6.09</td><td>15</td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.87</td><td>.08</td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.31</td><td>.000076</td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">Gliese 638 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 122px; top: 35px"><font color="black">• GLIESE 638 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> No extra info available. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">31.9 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K7V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>8.15</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>?</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>?</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">12 Ophiuchi </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 125px; top: 60px"><font color="black">• 12 OPHIUCHI </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> 12 Ophiuchi is lightly variable. The habitable zone would be from .6 to 1.1 AU. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">31.9 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K2V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.82</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.83</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.39</td><td></td> <td></td></tr> <tr><td colspan=6> </td></tr> <tr bgcolor="#6E1203"> <td colspan="4"><h3><a name="G892">HR 511 </a></h3></td> <td rowspan=6> <div style="position: relative"><img src="ministars.gif"> <div style="position: absolute; left: 320px; top: 15px"><font color="black">•</a></div> <div style="position: absolute; left: 260px; top: 15px"><font color="black">HR 511 </a></div> </div></td> <td rowspan=6>   </td> <td rowspan=6 bgcolor="#F2EED1">  </td> <td rowspan=6 bgcolor="#F2EED1"><font color="black"> HR 511, also called Gliese 75, is somewhat dimmer than the sun, and about the same age. The habitable zone would center around .7 AU. </font></td></tr> <tr bgcolor="#6E1203"> <td>Distance </td> <td colspan="3">32.8 ly</td></tr> <tr bgcolor="#6E1203"> <td>Type</td> <td>K0V</td> <td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Abs Magn </td><td>5.64</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"> <td>Mass </td><td>.85</td><td></td> <td></td></tr> <tr bgcolor="#6E1203"><td>Luminosity    </td><td>.53</td><td></td> <td></td></tr> </table> <h3><a name="Further">Further out</a></h3> For stars beyond 10 parsecs, see <a href="http://en.wikipedia.org/wiki/List_of_nearest_bright_stars">this Wikipedia page</a>, or <a href="http://www.solstation.com/stars.htm">SolStation</a>. </body> </html>