9.3 The Solar Neighbourhood

No known star (other than the Sun) is within 1 light-year or even 1 parsec of Earth. The stellar neighbours nearest the Sun are three stars in the constellation of Centaurus. To the unaided eye, the brightest of these three stars is Alpha Centauri, which is only 30○ from the south celestial pole and hence not visible from the mainland United States. Alpha Centauri itself is a binary star—two stars in mutual revolution—too close together to be distinguished without a telescope. These two stars are 4.4 light-years from us. Nearby is a third faint star, known as Proxima Centauri. Proxima, with a distance of 4.3 light-years, is slightly closer to us than the other two stars. If Proxima Centauri is part of a triple star system with the binary Alpha Centauri, as seems likely, then its orbital period may be longer than 500,000 years.

Table 9.1. The Nearest Stars, Brown Dwarfs, and White Dwarfs
Star System Discovery Name Distance (light-year) Spectral Type Location: RA1[1] Location: Dec2[2] Luminosity (Sun = 1)
Sun — G2 V — — 1
1 1 Proxima Centauri 4.2 M5.5 V 14 29 −62 40 5 × 10−5
2 2 Alpha Centauri A 4.4 G2 V 14 39 −60 50 1.5
3 Alpha Centauri B 4.4 K2 IV 14 39 −60 50 0.5
4 3 Barnard’s Star 6.0 M4 V 17 57 +04 42 4.4 × 10−4
5 4 Wolf 359 7.8 M6 V 10 56 +07 00 2 × 10−5
6 5 Lalande 21 185 8.3 M2 V 11 03 +35 58 5.7 × 10−3
7 6 Sirius A 8.6 A1 V 06 45 −16 42 23.1
8 Sirius B 8.6 DA2[3] 06 45 −16 43 2.5 × 10−3
9 7 Luyten 726-8 A 8.7 M5.5 V 01 39 −17 57 6 × 10−5
10 Luyten 726-8 B (UV Ceti) 8.7 M6 V 01 39 −17 57 4 × 10−5
11 8 Ross 154 9.7 M.05 V 18 49 −23 50 5 × 10−4
12 9 Ross 248 (HH Andromedae) 10.3 M5.5 V 23 41 +44 10 1.0 × 10−4
13 10 Epsilon Eridani 10.5 K2 V 03 32 −09 27 0.29
14 11 Lacaille 9352 10.7 M0.5 V 23 05 −35 51 0.011
15 12 Ross 128 (FI Virginis) 10.9 M4 V 11 47 +00 48 3.4 × 10−4
16 13 Luyten 789-6 A (EZ Aquarii A) 11.3 M5 V 22 38 −15 17 5 × 10−5
17 Luyten 789-6 B (EZ Aquarii B) 11.3 M5.5 V 22 38 −15 15 5 × 10−5
18 Luyten 789-6 C (EZ Aquarii C) 11.3 M6.5 V 22 38 −15 17 2 × 10−5
19 14 61 Cygni A 11.4 K5 V 21 06 +38 44 0.086
20 61 Cygni B 11.4 K7 V 21 06 +38 44 0.041
21 15 Procyon A 11.4 F51V 07 39 +05 13 7.38
22 Procyon B 11.4 wd[4] 07 39 +05 13 5.5 × 10−4
23 16 Sigma 2398 A 11.5 M3 V 18 42 +59 37 0.003
24 Sigma 2398 B 11.5 M3.5 V 18 42 +59 37 1.4 × 10−3
25 17 Groombridge 34 A (GX Andromedae) 11.6 M1.5 V 00 18 +44 01 6.4 × 10−3

Attribution

“19.2 Surveying the Stars” and “A.9 The Nearest Stars, Brown Dwarfs, and White Dwarfs” from Douglas College Astronomy 1105 by Douglas College Department of Physics and Astronomy, are licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted. Adapted from Astronomy 2e.

  1. Location (right ascension) given for Epoch 2000.0 ↵
  2. Location (declination) given for Epoch 2000.0 ↵
  3. White dwarf stellar remnant ↵
  4. White dwarf stellar remnant ↵

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Fanshawe College Astronomy Copyright © 2023 by Dr. Iftekhar Haque is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.