HD 36780

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

Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G.; Valentini, M.; Torralba Elipe, G.; Steinmetz, M.; Pantaleoni-González, M.; Malhotra, S.; Jiménez-Arranz, Ó.; Enke, H.; Casamiquela, L.; Ardèvol, J. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics. 691: A98. arXiv:2407.06963. Bibcode:2024A&A...691A..98K. doi:10.1051/0004-6361/202451427.
Fetherolf, Tara; Pepper, Joshua; Simpson, Emilie; Kane, Stephen R.; Močnik, Teo; English, John Edward; Antoci, Victoria; Huber, Daniel; Jenkins, Jon M.; Stassun, Keivan; Twicken, Joseph D.; Vanderspek, Roland; Winn, Joshua N. (2023). "Variability Catalog of Stars Observed during the TESS Prime Mission". The Astrophysical Journal Supplement Series. 268 (1): 4. arXiv:2208.11721. Bibcode:2023ApJS..268....4F. doi:10.3847/1538-4365/acdee5.
Kordopatis, G.; Schultheis, M.; McMillan, P. J.; Palicio, P. A.; De Laverny, P.; Recio-Blanco, A.; Creevey, O.; Álvarez, M. A.; Andrae, R.; Poggio, E.; Spitoni, E.; Contursi, G.; Zhao, H.; Oreshina-Slezak, I.; Ordenovic, C.; Bijaoui, A. (2023). "Stellar ages, masses, extinctions, and orbital parameters based on spectroscopic parameters of Gaia DR3". Astronomy and Astrophysics. 669: A104. arXiv:2206.07937. Bibcode:2023A&A...669A.104K. doi:10.1051/0004-6361/202244283.
De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (2014). "A catalog of rotational and radial velocities for evolved stars. V. Southern stars". Astronomy and Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762.
"HD 36780". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 13 March 2017.

[Anderson2012-1] Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.

[GaiaDR3-2] Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.

[HD-3] Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.

[UBVRI-4] Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.

[khalatyan2024-5] Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G.; Valentini, M.; Torralba Elipe, G.; Steinmetz, M.; Pantaleoni-González, M.; Malhotra, S.; Jiménez-Arranz, Ó.; Enke, H.; Casamiquela, L.; Ardèvol, J. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics. 691: A98. arXiv:2407.06963. Bibcode:2024A&A...691A..98K. doi:10.1051/0004-6361/202451427.

[fetherolf2023-6] Fetherolf, Tara; Pepper, Joshua; Simpson, Emilie; Kane, Stephen R.; Močnik, Teo; English, John Edward; Antoci, Victoria; Huber, Daniel; Jenkins, Jon M.; Stassun, Keivan; Twicken, Joseph D.; Vanderspek, Roland; Winn, Joshua N. (2023). "Variability Catalog of Stars Observed during the TESS Prime Mission". The Astrophysical Journal Supplement Series. 268 (1): 4. arXiv:2208.11721. Bibcode:2023ApJS..268....4F. doi:10.3847/1538-4365/acdee5.

[kordopatis2023-7] Kordopatis, G.; Schultheis, M.; McMillan, P. J.; Palicio, P. A.; De Laverny, P.; Recio-Blanco, A.; Creevey, O.; Álvarez, M. A.; Andrae, R.; Poggio, E.; Spitoni, E.; Contursi, G.; Zhao, H.; Oreshina-Slezak, I.; Ordenovic, C.; Bijaoui, A. (2023). "Stellar ages, masses, extinctions, and orbital parameters based on spectroscopic parameters of Gaia DR3". Astronomy and Astrophysics. 669: A104. arXiv:2206.07937. Bibcode:2023A&A...669A.104K. doi:10.1051/0004-6361/202244283.

[demedeiros2014-8] De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (2014). "A catalog of rotational and radial velocities for evolved stars. V. Southern stars". Astronomy and Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762.

[SIMBAD-9] "HD 36780". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 13 March 2017.

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Observation data Epoch J2000 Equinox ICRS
Location of HD 36780 (circled) in the Orion's Belt region Credit: Martin Mutti
Constellation	Orion¹
Right ascension	05^h 34^m 04.04753^s²
Declination	−01° 28′ 12.8726″²
Apparent magnitude (V)	+5.92¹
Characteristics
Evolutionary stage	giant
Spectral type	K4 III³
U−B color index	+1.87⁴
B−V color index	+1.535±0.008¹
Astrometry
Radial velocity (R_v)	82.45±0.21² km/s
Proper motion (μ)	RA: −8.295² mas/yr Dec.: −31.553² mas/yr
Parallax (π)	6.2074±0.0975 mas²
Distance	525 ± 8 ly (161 ± 3 pc)
Absolute magnitude (M_V)	−0.65¹
Details
Mass	1.2⁵ `M`_☉
Radius	33.8⁶ R_☉
Luminosity	279⁶ `L`_☉
Surface gravity (log g)	1.43⁷ cgs
Temperature	4,058⁶ K
Rotational velocity (v sin i)	2.1⁸ km/s
Age	12.4⁷ Gyr
Other designations
BD−01°950, GC 6894, HD 36780, HIP 26108, HR 1874, SAO 132270⁹
Database references
SIMBAD	data