Nearest Stars & Planets

Here’s a table of all known star systems within 15 light years (ly) of our Solar System. I will endeavor to keep this list up to date, so please post a comment here if anything needs to be corrected or added.

There are 41 star systems1 within a volume of

$V = \frac{4}{3}\pi r^{3} = \frac{4}{3}\pi (15\;ly)^{3} = 14,137\;ly^{3}$

Assuming that these 41 star systems are uniformly distributed within a sphere of radius 15 ly, the average distance from any star to its nearest neighbor is given by

$\bar{d} = r\left [ \frac{\pi }{3n\;\sqrt[]{2}} \right ]^{\frac{1}{3}} = (15\; ly)\left [ \frac{\pi }{3(41)\;\sqrt[]{2}} \right ]^{\frac{1}{3}} = 3.94\;ly$

So, even though it seems that 41 star systems within a distance of 15 ly from our Solar System is a lot, the volume of 14,137 cubic light years is not that small, and the average distance between any star and its nearest neighbor is about 3.94 ly. Our nearest neighbor is Proxima Centauri, which at a distance of 4.24 ly is quite close to the 3.94 ly average distance derived above.

Nearest Stars (within 15 light years)

 Star Distance (ly) Spectral Type Constellation Planets? Sun 0.00 G2V zodiacal Yes Proxima Centauri 4.24 M5.0V Centaurus Yes Alpha Centauri A & B 4.36 G2V & K0.0V Centaurus Unknown Barnard's Star 5.97 M3.5V Ophiuchus Unknown Luhman 16 A & B 6.59 L8 & T1 Vela Unknown WISE 0855-0714 7.26 Y2 Hydra Unknown Wolf 359 7.87 M5.5V Leo Yes Lalande 21185 8.29 M2.0V Ursa Major Yes Sirius A & B 8.65 A1V & DA2 Canis Major Unknown Luyten 726-8 A & B 8.79 M5.5V & M6.0V Cetus Unknown Ross 154 9.70 M3.5V Sagittarius Unknown Ross 248 10.29 M5.5V Andromeda Unknown Epsilon Eridani 10.48 K2.0V Eridanus Yes Lacaille 9352 10.72 M1.0V Piscis Austrinus Yes Ross 128 11.01 M4.0V Virgo Yes EZ Aquarii A, B, & C 11.27 M5.0VJ Aquarius Unknown 61 Cygni A & B 11.40 K5.0V & K7.0V Cygnus Unknown Procyon A & B 11.44 F5IV-V & DQZ Canis Minor Unknown Struve 2398 A & B 11.49 M3.0V & M3.5V Draco Yes Groombridge 34 A & B 11.62 M1.5V & M3.5V Andromeda Yes DX Cancri 11.68 M6.0V Cancer Unknown Epsilon Indi A, B, & C 11.81 K4.0V, T1, & T6 Indus Yes Tau Ceti 11.89 G8.5V Cetus Yes Gliese 1061 11.98 M5.0V Horologium Yes YZ Ceti 12.11 M4.0V Cetus Yes Luyten's Star 12.25 M3.5V Canis Minor Yes Teegarden's Star 12.50 M6.5V Aries Yes Kapteyn's Star 12.83 M2.0VI Pictor Unknown Lacaille 8760 12.95 K9.0V Microscopium Unknown SCR 1845-6357 A & B 13.05 M8.5 & T6 Pavo Unknown Kruger 60 A & B 13.08 M3.0V & M4.0V Cepheus Unknown DENIS J1048-3956 13.19 M8.5V Antlia Unknown UGPS 0722-05 13.43 T9 Monoceros Unknown Ross 614 A & B 13.49 M4.0V & M5.5V Monoceros Unknown Wolf 424 A & B 13.98 M5.0VJ Virgo Unknown Wolf 1061 14.05 M3.5V Ophiuchus Yes van Maanen 2 14.07 DZ7 Pisces Unknown Gliese 1 14.17 M1.5V Sculptor Unknown TZ Arietis 14.59 M4.0V Aries Yes Gliese 674 14.84 M2.5V Ara Yes Gliese 687 14.84 M3.0V Draco Yes LHS 292 14.90 M6.5V Sextans Unknown

1 Here we are considering Proxima Centauri and Alpha Centauri A & B to be one star system.

References
Henry, T.J. 2020, The Nearest Stars in The Observer’s Handbook 2023, ed. J. Edgar, The Royal Astronomical Society of Canada, p. 284-288.

The Nearest Stars

Within 5 light years (ly) of the Earth, there are 4 stars known (just the Sun and the Alpha Centauri system).  Within 10 ly, there are 15.  Within 15 ly, there are 58 stars.  The number goes up—rapidly!  Undoubtedly, more stars will be discovered within 15 light years of the Sun.

And, cool is the rule when it comes to nearby stars.  Of the 58 known stars within 15 ly of Earth, an amazing 37 (64%) are class M stars.  The remaining 36% include one A star, one F star, three G stars, six K stars, one L infrared dwarf, five very cool T infrared dwarfs, one extremely cool Y infrared dwarf, and three white dwarfs.

The hottest (and bluest) star within 15 light years of the Sun is none other than Sirius (α Canis Majoris)—the brightest star in the night sky—just 8.65 light years distant.  Sirius A is an A1V (main-sequence) star, twice as massive as our Sun, 71% wider, 25 times more luminous, and only 237 to 247 million years old—just a single orbit around the galactic center.  Sirius rotates much faster than the Sun, too, spinning around once on its axis every 5.4 days.  Think about all these things the next time you look up and see Sirius chasing Orion across the meridian these late-winter eves.  And that Sirius has a white dwarf companion that orbits it once every 50 years, too.

All but two of the nearest 48 stars that are not white dwarfs or infrared dwarfs have a luminosity class of V, meaning they are dwarf or main-sequence stars.  The first exception is Procyon (α CMi A).  Its luminosity class of IV-V indicates it is bright for its temperature and spectral type (F5) and beginning to evolve into a subgiant star on its way towards becoming a giant star.  The other exception is Kapteyn’s Star, a red subdwarf star of spectral type and luminosity class M2VI.  A subdwarf star is underluminous for its temperature and spectral type.  This is caused by low metallicity.  The scarcity of elements other than hydrogen and helium in the star results in a more transparent stellar photosphere and thus a star that is a little smaller than it normally would be.  Incidentally, the fact that we have three white dwarf stars within just 15 light years of us suggests that white dwarfs are copious throughout our galaxy.

You might be wondering how many planets have been discovered orbiting these 58 nearest stars.  Beyond the eight planets orbiting our Sun we find another eighteen confirmed planets, plus at least three more unconfirmed planets.  This is a rapidly advancing field and no doubt many more planets will be added to the list in the coming decade.

The masses of the confirmed planets include one 55% more massive than Jupiter, one a little more massive than Neptune, one a little less massive than Uranus, thirteen super-Earths (1.14 M up to 7.7 M), and two less massive than Earth (0.75 M and 0.98 M).  Their orbital periods range from 2 up to 636 terrestrial days, and then one planet (the super-Jupiter) orbiting once every 6.9 years.  Orbital eccentricities range from circular (0.00) to 0.55, with the super-Jupiter in a very elliptical orbit having an eccentricity of 0.702.  The super-Jupiter is orbiting Epsilon Eridani (K2V, 10.48 ly), with all the rest of the confirmed exoplanets orbiting M-dwarf stars except for the four close-in planets orbiting Tau Ceti (G8.5V, 11.89 ly).

References
NASA Exoplanet Archive https://exoplanetarchive.ipac.caltech.edu.
“The Nearest Stars” by Todd J. Henry, Observer’s Handbook 2019, RASC, pp. 286-290.