9 Equulei

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
Spectral type M2IIIa[3]
U−B color index +1.97[4]
B−V color index +1.66[4]
Variable type suspected[5]
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]
Distance740 ± 30 ly
(228 ± 9 pc)
Absolute magnitude (MV)−0.69[6]
Details
Radius58[1] R☉
Luminosity720[1] L☉
Temperature3,920[1] K
Other designations
HIP 105413, HD 203291, HR 8163, SAO 126719
Database references
SIMBADdata

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.[7] It is also a suspected variable star with an amplitude of about 0.05 magnitudes.[5]

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.

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