HD 36780

Location of HD 36780 (circled) in the Orion's Belt region Credit: Martin Mutti
Observation data Epoch J2000      Equinox J2000
Constellation	Orion[1]
Right ascension	05h 34m 04.04753s[2]
Declination	−01° 28′ 12.8726″[2]
Apparent magnitude (V)	+5.92[1]
Characteristics
Evolutionary stage	giant
Spectral type	K4 III[3]
U−B color index	+1.87[4]
B−V color index	+1.535±0.008[1]
Astrometry
Radial velocity (Rv)	82.45±0.21[2] km/s
Proper motion (μ)	RA: −8.295[2] mas/yr Dec.: −31.553[2] mas/yr
Parallax (π)	6.2074±0.0975 mas[2]
Distance	525 ± 8 ly (161 ± 3 pc)
Absolute magnitude (MV)	−0.65[1]
Details
Mass	1.2[5] M☉
Radius	33.8[6] R☉
Luminosity	279[6] L☉
Surface gravity (log g)	1.43[7] cgs
Temperature	4,058[6] K
Rotational velocity (v sin i)	2.1[8] km/s
Age	12.4[7] Gyr
Other designations
BD−01°950, GC 6894, HD 36780, HIP 26108, HR 1874, SAO 132270[9]
Database references
SIMBAD	data

HD 36780 is a star located in Orion's Belt, within the equatorial constellation of Orion. It has an orange hue and is dimly visible to the naked eye with an apparent visual magnitude of +5.92.^[1] The distance to this object is approximately 525 light years based on parallax.^[2] It is drifting away from the Sun with a radial velocity of 82 km/s,^[2] having come to within 185.6 light-years some 2.1 million years ago.^[1]

This is an aging giant star with a stellar classification of K4 III.^[3] After exhausting the supply of hydrogen at its core, the star cooled and expanded off the main sequence. At present it has around 34 times the girth of the Sun. It is radiating 279 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,058 K.^[6]

References