HD 39118

HD 39118

Basic layout of the HR 2024 system.
Observation data
Epoch J2000      Equinox J2000
Constellation Orion[a]
Right ascension 05h 50m 30.03s[1]
Declination 02° 01′ 28.93″[1]
Apparent magnitude (V) 5.976[1]
Characteristics
Cool primary
Evolutionary stage Red giant branch[2]
Spectral type K0II[3]
Apparent magnitude (B) 6.83±0.015[1]
Apparent magnitude (G) 5.64[1]
Apparent magnitude (J) 4.193±0.238[1]
Apparent magnitude (H) 3.502±0.194[1]
Apparent magnitude (K) 3.337±0.19[1]
B−V color index 1.12[3]
Hot secondary
Evolutionary stage B-type main-sequence star + A-type main-sequence star
Spectral type B7V/B8V + A0V[3]
B−V color index -0.09[3]
Astrometry
Radial velocity (Rv)4.24[3] km/s
Proper motion (μ) RA: 1.097 mas/yr[1]
Dec.: -5.161 mas/yr[1]
Parallax (π)1.47 ± 0.23 mas[4]
Distance2300+350
−270 ly
(707.6+107
−83.3 pc)[4]
Absolute magnitude (MV)–2.53
(–2.3 (primary) + –0.75 (secondary))[3]
Orbit
PrimaryCool primary
CompanionHot secondary
Period (P)2570±13 d
7.04±0.04 year[5]
Semi-major axis (a)4.7×108 km
3.14 AU[5]
Eccentricity (e)0.3±0.007[5]
Details
K-type giant
Mass3.3+0.3
−0.27[2] M☉
Radius23.5+3.7
−1.9[2] R☉
Luminosity535[6] L☉
Surface gravity (log g)1.52[7] cgs
Temperature4,550[7] K
Metallicity [Fe/H]-0.34[7] dex
Rotational velocity (v sin i)4.19[8] km/s
Age257[2] Myr
B-type star
Temperature11,300[9] K
Other designations
BD+01 1148, Gaia DR2 3316078695157768448, Gaia DR3 3316078695157768448, HD 39118/39119, HIP 27588, HR 2024, SAO 113198, PPM 149543, TIC 158867386, TYC 120-877-1, GSC 00120-00877, IRAS 05478+0200, 2MASS J05503003+0201290
Database references
SIMBADdata

HD 39118 (HD 39119, HR 2024) is a spectroscopic binary star in the constellation Orion, close to the celestial equator. It is made up from three stars: a cool primary (a K-type giant star) and a hot secondary, which is a binary star formed from a B-type main-sequence star and an A-type main-sequence star. A 2021 estimate derive a distance of 708 parsecs (2,310 ly) to HD 39118, and it is moving away from Earth at a speed of 4.24 km/s. The apparent magnitude is 5.976, making it visible to the naked eye only from dark skies.


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