V1073 Scorpii

This article is about k Scorpii and is not to be confused with κ (kappa) Scorpii.

V1073 Scorpii is a variable star in the constellation Scorpius. It has a non-Greek Bayer designation of k Scorpii. The star has a blue-white hue and is visible to the naked eye with an apparent visual magnitude that fluctuates around +4.87.^[2] Parallax measurements yield a distance estimate of approximately 2,920 ly (896 pc) from the Sun, and it is drifting further away with a radial velocity of +7 km/s.^[5] It has an absolute magnitude of −6.8^[6]

A light curve for V1073 Scorpii, adapted from Lefèvre et al. (2009)^[11]

V1073 Scorpii

Location of V1073 Scorpii (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Scorpius
Right ascension	17h 04m 49.35254s[1]
Declination	−34° 07′ 22.5483″[1]
Apparent magnitude (V)	+4.87[2]
Characteristics
Spectral type	B0.7 Ia[3]
U−B color index	−0.69[2]
B−V color index	+0.26[2]
Variable type	α Cyg[4]
Astrometry
Radial velocity (Rv)	7.00[5] km/s
Proper motion (μ)	RA: +0.600[1] mas/yr Dec.: −2.015[1] mas/yr
Parallax (π)	1.1161±0.2097 mas[1]
Distance	approx. 2,900 ly (approx. 900 pc)
Absolute magnitude (MV)	−6.8[6]
Details
Mass	28[7] 19.7±1.0[8] 27.11±8.39[9] M☉
Radius	36.0[6][3] R☉
Luminosity	302,000[6] L☉
Surface gravity (log g)	2.70[7] 2.65[3] cgs
Temperature	20,800[9] 22,500[3] K
Rotational velocity (v sin i)	47[7] km/s
Age	4.2±0.3[8] Myr
Other designations
k Sco, V1073 Sco, CD−33°11706, HD 154090, HIP 83574, HR 6334, SAO 208377[10]
Database references
SIMBAD	data

This object is a massive supergiant star with a stellar classification of B0.7 Ia.^[3] It is an α Cygni variable;^[12] a supergiant that pulsates erratically on a timescale of days to weeks with an amplitude of less than a tenth of a magnitude. A simplistic fitting of Hipparcos data suggests a periodicity of 1.6 days.^[13][11] The star is around 4.2^[8] million years old and is a member of the Upper Scorpius subgroup of the Sco OB2 association.^[14] V1073 Scorpii is considered a "runaway" star, showing a peculiar velocity of more than 37 km/s relative to its neighbourhood.^[8] No bow shock has been detected from its motion through interstellar space.^[15]

V1073 Sco has a 14th magnitude visual companion,^[16] which is an unrelated background object according to its Gaia Data Release 2 parallax.^[17]