31 Aquilae

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**31 Aquilae**
Observation data Epoch J2000
Image:31 Aquilae.jpg 31 Aquilae
Constellation (pronunciation)	Aquila
Right ascension	19^h 24^m 58.2004^s
Declination	+11° 56′ 39.896″
Apparent magnitude (V)	5.16
Characteristics
Spectral type	G8IV
U-B color index	0.45
B-V color index	0.77
Variable type	variable
Astrometry
Radial velocity (R_v)	-100.1 km/s
Proper motion (μ)	RA: 721.36 mas/yr Dec.: 643.67 mas/yr
Parallax (π)	66.01 ± 0.77 mas
Distance	49.4 ± 0.6 ly (15.1 ± 0.2 pc)
Absolute magnitude (M_V)	5.93
Details
Mass	? M_☉
Radius	? R_☉
Luminosity	? L_☉
Temperature	? K
Metallicity	?
Rotation	?
Age	? years
Visual binary orbit
Companion	31 Aquilae B
Semimajor axis (a)	98.7"
Inclination (i)	335°
Visual binary orbit
Companion	31 Aquilae C
Semimajor axis (a)	114.2"
Inclination (i)	316°
Other designations
NSV 11994, GCRV 11861, LTT 15668, SRS 31503, b Aql, 2MASS J19245822+1156401, TD1 24621, 31 Aql, GJ 759, N30 4300, TYC 1063-519-1, AG+11° 2263, HD 182572, NLTT 47763, UBV 16443, ASCC 976604, HIC 95447, PLX 4541, UBV M 23748, BD+11° 3833, HIP 95447, PMC 90-93 1065, USNO-B1.0 1019-00522349, [[ CCDM]] J19249+1157A, HR 7373, PM 19226+1150, YZ 11 7220, Ci 20 1152, IDS 19202+1143 A, PPM 136256, CSI+11 3833 1, IRAS 19226+1150, ROT 2792, CSV 101833, LFT 1477, SAO 104807, FK5 1503, LHS 3463, GC 26809, LSPM J1924+1156, SPOCS 840.
Database references
SIMBAD	data
Database references
SIMBAD	data

31 Aquilae (b Aquilae) is a subgiant star in the constellation Aquila. Its apparent magnitude is 5.17. Its age is probably similar to NGC 188,the oldest open cluster known, which was calculated to be over 5 billion years. For its age, it is surprisingly metal rich, contrary to common assumptions that the oldest stars should be metal-poor.