GX Velorum

GX Velorum is a solitary^[12] variable star^[3] in the southern constellation of Vela. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude that fluctuates around 4.99.^[2] Based upon parallax measurements, it is located approximately 4,200 light years distant from the Sun, and is drifting further away with a radial velocity of +28 km/s.^[6] It may be a member of the Vela OB1 association of co-moving stars.^[7]

A light curve for GX Velorum, plotted from Hipparcos data^[13]

GX Velorum

Location of GX Velorum (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Vela
Right ascension	09h 11m 04.39802s[1]
Declination	−44° 52′ 04.4411″[1]
Apparent magnitude (V)	+4.99[2] (4.97 to 5.04)[3]
Characteristics
Spectral type	B5 Ia[4]
U−B color index	−0.57[5]
B−V color index	+0.22[5]
Variable type	α Cyg?[3]
Astrometry
Radial velocity (Rv)	+28.2±0.8[6] km/s
Proper motion (μ)	RA: −5.608[1] mas/yr Dec.: +3.843[1] mas/yr
Parallax (π)	0.7696±0.1585 mas[1]
Distance	approx. 4,200 ly (approx. 1,300 pc)
Absolute magnitude (MV)	−7.20[7]
Details[8]
Mass	35 M☉
Radius	61±7[9] R☉
Luminosity	214,000[9] L☉
Surface gravity (log g)	2.12±0.05[9] cgs
Temperature	15,000±150[9] K
Rotational velocity (v sin i)	39 km/s
Age	8.3[10] Myr
Other designations
GX Vel, CD−44°5206, HD 79186, HIP 45085, HR 3654, SAO 220928[11]
Database references
SIMBAD	data

This object is a massive blue supergiant with a stellar classification of B5 Ia.^[4] It is suspected to be an Alpha Cygni-type pulsating variable and ranges in brightness from 4.97 down to 5.04 magnitude.^[3] It is losing mass at the rate of (0.40±0.02)×10⁻⁶ M_☉ yr⁻¹,^[9] or one solar mass every 2.5 million years. The star is 8.3^[10] million years old with 35 times the mass of the Sun.^[8] It has expanded to around 61^[9] times the Sun's radius and is radiating 214,000^[9] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 15,000 K.^[9]