Double Star
Five faint stars appear close enough to Aldebaran in its visual field for astronomers to consider it a double star association. These stars were given alphabetic secondary star designations more or less in the order of their discovery, with the letter A reserved for the primary star. The better known characteristics of these optical double stars are listed in the table below with the primary star, Aldebaran (Alpha Tauri A), shown for reference.
| Star α Tauri |
Right ascension |
Declination | Apparent magnitude |
Distance |
Proper motion |
Spectral type |
Absolute magnitude |
Other names | References |
|---|---|---|---|---|---|---|---|---|---|
| A | 04h 35m 55.239s | +16° 30′ 33.49″ | 0.85 | 65 | RA: 62.78 ±0.89 Dec.: −189.35 ±0.58 |
K5III | −0.63 | Aldebaran, GJ 171.1 A, ADS 3321 A, BD +16°629A |
|
| B | 04h 35m 57.0s | +16° 30′ 22″ | 13.6 | RA: 64 ±25 Dec.: -191 ±25 |
M2V | 11.98 | GJ 171.1 B | ||
| C | 04h 35m 55.5s | +16° 30′ 38″ | 9.4 | ADS 3321 C | |||||
| D | 04h 35m 55.5s | +16° 30′ 38″ | 11.8 | ADS 3321 D | |||||
| E | 04h 35m 53.8s | +16° 31′ 08″ | BD +16°629E | ||||||
| F | 04h 33.3m | +16° 22′ | 13.6 | BD +16°629F |
Some surveys have indicated that Alpha Tauri B may have about the same proper motion and parallax as Aldebaran and thus may be a physical binary system. However these measurements are difficult to make because the dim B component appears so close to the bright primary star. The resulting margin of error is too large to positively establish (or exclude) a physical relationship between the two stars. So far neither the B component, nor anything else, has been unambiguously shown to be physically associated with Aldebaran.
Alpha Tauri CD is a binary system with the C and D component stars gravitationally bound to and co-orbiting each other. These co-orbiting stars have been shown to be located far beyond Aldebaran and are members of the Hyades star cluster. As with the rest of the stars in the cluster they do not physically interact with Aldebaran in any way.
Read more about this topic: Aldebaran
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