HD 74438

HD 74438 is a spectroscopic quadruple stellar system composed of a pair of double star systems approximately 425 light years from Earth, located in open cluster IC 2391.^[5][6] With an estimated age of 43+15
−7 million years,^[4] HD 74438 is the youngest quadruple star system known.^[7] The outer orbital period of the system, estimated at around 5.7 years, is also among the shortest of quadruple systems.^[4][7]

HD 74438

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Vela
Right ascension	08h 41m 46.5806s[1]
Declination	−52° 03′ 44.996″[1]
Apparent magnitude (V)	+7.59 (8.2/8.2/9.4/9.4)[2]
Characteristics
Spectral type	A2mA5-A8[3]
Astrometry
Proper motion (μ)	RA: −17.745[1] mas/yr Dec.: +17.056[1] mas/yr
Parallax (π)	6.9075±0.0755 mas[1]
Distance	472 ± 5 ly (145 ± 2 pc)
Orbit[4]
Primary	AB
Companion	CD
Period (P)	2,074.2±3.5 days
Semi-major axis (a)	5.54±0.04 au
Eccentricity (e)	0.458±0.015
Inclination (i)	73.2 or 106.8°
Semi-amplitude (K1) (primary)	12.8±0.3 km/s
Semi-amplitude (K2) (secondary)	18.5±0.4 km/s
Orbit[4]
Primary	A
Companion	B
Period (P)	20.5729±0.0003 days
Semi-major axis (a)	0.215±0.002 au
Eccentricity (e)	0.3692±0.0001
Inclination (i)	52.5 or 127.5°
Semi-amplitude (K1) (primary)	45.81±0.09 km/s
Semi-amplitude (K2) (secondary)	50.77±0.09 km/s
Orbit[4]
Primary	C
Companion	D
Period (P)	4.4243±0.0001 days
Semi-major axis (a)	0.0681±0.001 au
Eccentricity (e)	0.1535±0.0003
Inclination (i)	84.0 or 96.0°
Semi-amplitude (K1) (primary)	45.81±0.09 km/s
Semi-amplitude (K2) (secondary)	50.77±0.09 km/s
Details[4]
A
Mass	1.70±0.06 M☉
Radius	1.46±0.15 R☉
Luminosity	8.87±1.40 L☉
Temperature	8,250±250 K
B
Mass	1.54±0.06 M☉
Radius	1.42±0.15 R☉
Luminosity	5.72±0.95 L☉
Temperature	7,500±250 K
C
Mass	0.96±0.14 M☉
Radius	0.84±0.36 R☉
Luminosity	0.64±0.51 L☉
Temperature	5,625±410 K
D
Mass	0.87±0.14 M☉
Radius	0.80±0.29 R☉
Luminosity	0.48±0.32 L☉
Temperature	5,375±410 K
Other designations
HD 74438, CD−52°2497, SAO 236190
Database references
SIMBAD	data

The HD 74438 system was confirmed to be a gravitationally bound quadruple system in 2017 from data collected in the Gaia-ESO Survey.^[5] In a paper published in 2022, HD 74438 was identified as a possible progenitor of a sub-Chandrasekhar Type Ia supernova.^[4]