9 Equulei
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Equuleus |
| Right ascension | 21h 21m 04.825s[1] |
| Declination | +07° 21′ 16.21″[1] |
| Apparent magnitude (V) | 5.798[2] |
| Characteristics | |
| Evolutionary stage | AGB[3] |
| Spectral type | M2IIIa[4] |
| U−B color index | +1.97[5] |
| B−V color index | +1.66[5] |
| Variable type | suspected[6] |
| Astrometry | |
| Radial velocity (Rv) | −21.82±0.30[1] km/s |
| Proper motion (μ) | RA: 43.871±0.274[1] mas/yr Dec.: −17.822±0.261[1] mas/yr |
| Parallax (π) | 4.3895±0.1647 mas[1] |
| Distance | 740 ± 30 ly (228 ± 9 pc) |
| Absolute magnitude (MV) | −0.69[7] |
| Details | |
| Mass | 1.2[8] M☉ |
| Radius | 58[1] R☉ |
| Luminosity | 720[1] L☉ |
| Surface gravity (log g) | 1.64[8] cgs |
| Temperature | 3,920[1] K |
| Metallicity [Fe/H] | −0.27[8] dex |
| Other designations | |
| HIP 105413, HD 203291, HR 8163, SAO 126719 | |
| Database references | |
| SIMBAD | data |
9 Equulei is an M-type star in the constellation Equuleus. It is an asymptotic giant branch (AGB) star, a star that has exhausted its core helium and is now fusing both hydrogen and helium in shells outside the core.[3] It is also a suspected variable star with an amplitude of about 0.05 magnitudes.[6]
The spectral type is M2IIIa, meaning it is a relatively cool giant star. As an AGB star, it is burning hydrogen and helium in shells around an inert carbon-oxygen core. It has expanded to 58 times the radius of the Sun, and it radiates 720 times as much electromagnetic radiation from a photosphere with an effective temperature of 3,920 K.
This star has been designated Eta Equulei by Johann Elert Bode, but the designation is generally unused now.[9]
References
[edit | edit source]- ^ a b c d e f g h i Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Gaia DR2 record for this source at VizieR.
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
