It is very difficult to determine the distances to the stars because they are so very far away. The distance to the closest stars can be measured through their parallax. In this technique, the location of a star is painstakingly measured twice, six months apart. (The Earth is on opposite sides of the Sun at the two measurements, providing a long baseline.) If the star is close enough, it will appear to "wobble" slightly compared to the distant stars (which are taken to be fixed in place). The parallax of a star is this tiny angle between the two measurements.
A number of the closest stars actually form multiple systems. Each component, usually labelled A, B, C, etc., is listed separately. The values for absolute magnitude and distance depend on the accuracy of the observations of the apparent magnitude and parallax. The Sun, which is the closest star to the Earth, is provided for comparison.
| Name | Apparent Magnitude |
Absolute Magnitude |
Parallax (arcseconds) |
Distance (parsecs) |
Distance (light years) |
|---|---|---|---|---|---|
| Sun | -26.7 | +4.87 | |||
| Proxima Centauri | +11.05 | +15.49 | 0.772 | 1.30 | 4.22 |
| Rigil Kent A | -0.01 | +4.34 | 0.742 | 1.35 | 4.40 |
| Rigil Kent B | +1.35 | +5.70 | 0.742 | 1.35 | 4.40 |
| Barnard's Star | +9.54 | +13.24 | 0.549 | 1.82 | 5.94 |
| Wolf 359 | +13.45 | +16.59 | 0.425 | 2.35 | 7.67 |
| Lalande 21185 | +7.49 | +10.46 | 0.392 | 2.55 | 8.32 |
| UV Ceti | +13.25 | +16.15 | 0.381 | 2.62 | 8.56 |
| Sirius A | -1.44 | +1.45 | 0.379 | 2.64 | 8.61 |
| Sirius B | +8.44 | +11.33 | 0.379 | 2.64 | 8.61 |
| BL Ceti | +12.41 | +15.27 | 0.374 | 2.67 | 8.72 |
| V1216 Sagittarii | +10.37 | +13.00 | 0.336 | 2.98 | 9.71 |
| HH Andromedae | +12.28 | +14.77 | 0.315 | 3.17 | 10.35 |
| epsilon Eridani | +3.72 | +6.18 | 0.311 | 3.22 | 10.49 |
| Lacaille 9352 | +7.35 | +9.76 | 0.304 | 3.29 | 10.73 |
| EZ Aquarii | +12.18 | +14.57 | 0.300 | 3.33 | 10.87 |
| FI Virginis | +11.08 | +13.47 | 0.300 | 3.33 | 10.87 |
| 61 Cygni A | +5.20 | +7.49 | 0.287 | 3.48 | 11.36 |
| Procyon A | +0.40 | +2.68 | 0.286 | 3.50 | 11.40 |
| Procyon B | +10.92 | +13.20 | 0.286 | 3.50 | 11.40 |
| 61 Cygni B | +6.05 | +8.32 | 0.285 | 3.51 | 11.44 |
| Struve 2398 B | +9.70 | +11.97 | 0.284 | 3.52 | 11.48 |
| Struve 2398 A | +8.94 | +11.18 | 0.280 | 3.57 | 11.65 |
| GX Andromedae | +8.09 | +10.33 | 0.280 | 3.57 | 11.65 |
| GQ Andromedae | +11.04 | +13.28 | 0.280 | 3.57 | 11.65 |
| DX Cancri | +14.81 | +17.01 | 0.276 | 3.62 | 11.82 |
| epsilon Indi | +4.69 | +6.89 | 0.276 | 3.62 | 11.82 |
| tau Ceti | +3.49 | +5.68 | 0.274 | 3.65 | 11.90 |
Proxima Centauri and the two components of Rigil Kent (or alpha Centauri as it is more usually known) form a triple system. Currently, Proxima Centauri is the closest member of this system to the Sun.
Barnard's Star has the greatest proper motion (apparent angular motion across the sky) of any known star.
Fans of the television series Star Trek will recognize Wolf 359 as the site of the epic battle between Starfleet and the Borg.
Astrometric observations suggest the possibility that Lalande 21185 is orbited by two Jupiter-like planets.
UV Ceti is a flare star, undergoing large changes of brightness in very short time frames. Flare stars are sometimes referred to as "UV Ceti variables" in honour of this remarkable behaviour. Its companion, BL Ceti, is also a flare star but doesn't exhibit such extreme behaviour.
Sirius B is a white dwarf, a star at the end of its life. An extremely dense object, it is slowly cooling down because it is no longer fusing atoms in its core to produce energy. At the end of its life, the Sun will also become a white dwarf.
In 1998, a dust ring, perhaps similar to the cloud of comets surrounding our own solar system, was discovered around the very young star epsilon Eridani.
EZ Aquarii is actually a triple system of red dwarf stars.
61 Cygni was the first star successfully observed for parallax. Friedrich Wilhelm Bessel (1784 - 1846) measured the parallax between 1837 and 1840.
Like Sirius B, Procyon B is a white dwarf.
In 2003, astronomers announced that epsilon Indi was accompanied by a brown dwarf. It was later discovered that the brown dwarf was actually a binary system.
tau Ceti features in many science fiction novels by virtue of the fact that it is the nearest single (non-multiple) solar-type star to the Sun.
You can experience parallax for yourself if you have two functioning eyes. Extend an arm out in front of you and give the "thumbs up" sign. Keeping your arm very still, close your left eye and look at your thumb. Note where it appears relative to the background. Now open your left eye, close your right eye, and do the same thing. Don't move your arm or your head! Your thumb should appear to have moved relative to the background. However, what has actually moved is the observer (your eyes). The distance between your two eyes provides the baseline for this experiment and the angle between the two observations is the parallax. The farther away an object is, the larger the baseline needs to be. This is why the diameter of the Earth's orbit around the Sun is used as the baseline for measuring stellar parallaxes. Even so, this method can only be used for the very nearest stars.
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