26 Vulpeculae

26 Vulpeculae is a close binary star^[5] system in the northern constellation of Vulpecula,^[9] around 644 light years away from the Sun.^[1] It is a challenge to view with the naked eye, having an apparent visual magnitude of 6.40.^[2] The star is moving closer to the Earth with a heliocentric radial velocity of −63 km/s,^[4] and is expected to come within 225 light-years in around 2.6 million years.^[2]

26 Vulpeculae

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Vulpecula
Right ascension	20h 36m 08.3399s[1]
Declination	+25° 52′ 57.5615″[1]
Apparent magnitude (V)	6.40[2]
Characteristics
Spectral type	A5 III[3]
B−V color index	0.158±0.005[2]
Astrometry
Radial velocity (Rv)	−63.4±2.3[4] km/s
Proper motion (μ)	RA: +26.010[1] mas/yr Dec.: +12.189[1] mas/yr
Parallax (π)	5.0684±0.0346 mas[1]
Distance	644 ± 4 ly (197 ± 1 pc)
Absolute magnitude (MV)	−0.04[2]
Orbit[5]
Period (P)	11.088 d
Eccentricity (e)	0.28
Periastron epoch (T)	2,426,492.6090 JD
Argument of periastron (ω) (secondary)	50.1°
Semi-amplitude (K1) (primary)	58.7 km/s
Details
Radius	4.6[6] R☉
Luminosity	79.75[7] L☉
Temperature	7,888[7] K
Rotational velocity (v sin i)	15[8] km/s
Other designations
26 Vul, BD+25°4299, HD 196362, HIP 101641, HR 7874, SAO 88884[9]
Database references
SIMBAD	data

This is a single-lined spectroscopic binary with an orbital period of 11 days and an eccentricity of 0.28.^[5] The visible component is a suspected chemically peculiar star^[10] with a stellar classification of A5 III,^[3] suggesting this is an evolved giant star. It has about 4.6^[6] times the Sun's radius and is radiating 80 times the Sun's luminosity from its photosphere at an effective temperature of 7,888 K.^[7]