KQ Puppis (KQ Pup) is a spectroscopic binary variable star in the constellation Puppis. A red supergiant star and a hot main sequence star orbit each other every 9,742 days. Its apparent magnitude varies between 4.82 and 5.17.

KQ Puppis

KQ Puppis is the bright red star on the right, with M47 on the left.
Observation data Epoch J2000      Equinox J2000
Constellation	Puppis
Right ascension	07h 33m 47.96383s[1]
Declination	−14° 31′ 26.0026″[1]
Apparent magnitude (V)	+4.97[2] (4.82 - 5.17[3])
Characteristics
Spectral type	M2Iab + B0Ve[4]
U−B color index	+0.29[2]
B−V color index	+1.41[2]
Variable type	LC[3]
Astrometry
Radial velocity (Rv)	+22[5] km/s
Proper motion (μ)	RA: -6.584[6] mas/yr Dec.: +3.34[6] mas/yr
Parallax (π)	1.4894 ± 0.2296 mas[6]
Distance	approx. 2,200 ly (approx. 700 pc)
Orbit[7]
Period (P)	9,752 days
Eccentricity (e)	0.46
Inclination (i)	60-80°
Details
Cool primary
Mass	13-20[7] M☉
Radius	415[8] R☉
Luminosity	26,500 - 28,100[8] L☉
Temperature	3,662[9][8] K
Hot secondary
Mass	17[7] M☉
Radius	4.35[7] R☉
Luminosity	13,800[7] L☉
Temperature	30,000[7] K
Other designations
KQ Pup, BD−14°1971, HIP 36773, HR 2902, NGC 2422 9, SAO 153072
Primary: HD 60414
Secondary: HD 60415
Database references
SIMBAD	data

The KQ Puppis system consists of a fairly typical M2 supergiant, in orbit with a hotter less luminous star. The hotter star is surrounded by a disc of material being transferred from the cool supergiant. This type of binary is referred to a VV Cephei system, although in this case there are no eclipses of either star.[7] A portion of the disc does appear to be eclipsed and this is detected as a strong drop in far-ultraviolet radiation for about a third of the orbit.[4]

The red supergiant primary star has been compared to Betelgeuse.[7] It shows small amplitude irregular pulsations, and also some variation associated with the orbital motion.[11] The nature of the secondary is less certain. The spectrum shows high excitation features that would indicate an early B or hotter spectral type, but these may be associated with the disc rather than that star itself. Other studies have found a spectrum similar to an A supergiant, but this is thought to be an artefact of a B-type shell star.[12]

KQ Puppis has been catalogued as an outlying member of the open cluster Messier 47 (NGC 2422) and would be the brightest member of that cluster.[13] Membership is uncertain as it appears to be more distant than the other stars in the cluster.[14]

References