15 Vulpeculae

15 Vulpeculae is a variable star in the northern constellation of Vulpecula, located approximately 236 light years away based on parallax.[1] It has the variable star designation NT Vulpeculae; 15 Vulpeculae is the Flamsteed designation. It is visible to the naked eye as a faint, white-hued star with a typical apparent visual magnitude of 4.66.[2] This object is moving closer to the Earth with a heliocentric radial velocity of −26 km/s.[6]

15 Vulpeculae

Location of 15 Vulpeculae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Vulpecula
Right ascension	20h 01m 06.04846s[1]
Declination	+27° 45′ 12.8639″[1]
Apparent magnitude (V)	4.66[2] (4.62 - 4.67)[3]
Characteristics
Spectral type	A4IIIm[3] or kA5hA7mA7 (IV–V)[4]
U−B color index	+0.15[5]
B−V color index	+0.18[5]
Variable type	α2 CVn[3]
Astrometry
Radial velocity (Rv)	−26.10[6] km/s
Proper motion (μ)	RA: +58.17[1] mas/yr Dec.: +3.84[1] mas/yr
Parallax (π)	13.80 ± 0.20[1] mas
Distance	236 ± 3 ly (72 ± 1 pc)
Absolute magnitude (MV)	0.36[2]
Details
Luminosity	59.76[2] L☉
Surface gravity (log g)	3.45[4] cgs
Temperature	8,084[7] K
Metallicity [Fe/H]	+0.02[2] dex
Rotational velocity (v sin i)	15.0[8] km/s
Other designations
15 Vul, NT Vul, BD+27°3587, FK5 1523, GC 27753, HD 189849, HIP 98543, HR 7653, SAO 88071[9]
Database references
SIMBAD	data

This is an Am star with a stellar classification of A4 IIIm,[3] matching an evolved A-type giant star. However, Gray & Garrison (1989) found a class of kA5hA7mA7 (IV–V),[4] which matches a blend of subgiant and main sequence luminosity classes with the K-line (kA5) of an A5 star and the hydrogen (hA7) and metal (mA7) absorption lines of an A7 star. It is an Alpha² Canum Venaticorum-type variable with magnitude ranging from 4.62 down to 4.67 over a period of 14 days.[3] The star is radiating 60[2] times the Sun's luminosity from its photosphere at an effective temperature of 8,084 K.[7]