37 Comae Berenices

37 Comae Berenices is a variable star system located around 690^[2] light years away from the Sun in the northern constellation of Coma Berenices.^[9] It has the variable star designation LU Comae Berenices. 37 Comae Berenices was a later Flamsteed designation of 13 Canum Venaticorum.^[10] This object is visible to the naked eye as a faint, yellow-hued star with a baseline apparent visual magnitude of 4.88.^[3] It is drifting closer to the Earth with a heliocentric radial velocity of −14 km/s.^[8]

37 Comae Berenices

A light curve for LU Comae Berenices, adapted from Henry et al. (2000).[1] The plotted brightness is the average of the Strömgren b and y magnitudes.
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Coma Berenices
Right ascension	13h 00m 16.46725s[2]
Declination	+30° 47′ 06.0644″[2]
Apparent magnitude (V)	4.88[3]
Characteristics
Evolutionary stage	Hertzsprung gap[4]
Spectral type	G9 III CH-2 CN-1[5]
B−V color index	1.165±0.014[6]
Variable type	RS CVn[7]
Astrometry
Radial velocity (Rv)	−14.34[8] km/s
Proper motion (μ)	RA: −18.662[2] mas/yr Dec.: −5.802[2] mas/yr
Parallax (π)	4.6981 ± 0.2586 mas[2]
Distance	690 ± 40 ly (210 ± 10 pc)
Absolute magnitude (MV)	−1.62[6]
Details[3]
Mass	5.25 M☉
Radius	38.2 R☉
Luminosity (bolometric)	590 L☉
Surface gravity (log g)	2.3 cgs
Temperature	4,625[4] K
Metallicity [Fe/H]	−0.05[4] dex
Rotation	111 days[4]
Rotational velocity (v sin i)	11±1[4] km/s
Other designations
37 Com, 12 CVn, LU Com, BD+31°2434, HD 112989, HIP 63462, HR 4929, SAO 96265[9]
Database references
SIMBAD	data

Tokovinin (2008) catalogued this as a wide triple star system.^[4] The primary component is an aging giant star, currently in the Hertzsprung gap,^[4] with a stellar classification of G9 III CH-2 CN-1.^[5] It is a weak G-band star,^[4] a luminous giant star with a carbon abundance about a factor of 5 lower than is typical for such stars.^[11] This is a variable star most likely of the RS CVn type with an amplitude of 0.15 in magnitude,^[7] and it displays magnetic activity.^[4] It has 5.25 times the mass of the Sun and, having exhausted the supply of hydrogen at its core, has expanded to 38 times the Sun's radius.^[3]

References

1. Henry, Gregory W.; Fekel, Francis C.; Henry, Stephen M.; Hall, Douglas S. (September 2000). "Photometric Variability in a Sample of 187 G and K Giants". The Astrophysical Journal Supplement Series. 130 (1): 201–225. Bibcode:2000ApJS..130..201H. doi:10.1086/317346. S2CID 17160805.
2. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
3. Aurière, M.; et al. (2015). "The magnetic fields at the surface of active single G-K giants". Astronomy & Astrophysics. 574: A90. arXiv:1411.6230. Bibcode:2015A&A...574A..90A. doi:10.1051/0004-6361/201424579. S2CID 118504829.
4. Tsvetkova, S.; et al. (March 2017). "Magnetic field structure in single late-type giants: The weak G-band giant 37 Comae from 2008 to 2011". Astronomy & Astrophysics. 599: 13. arXiv:1612.02669. Bibcode:2017A&A...599A..72T. doi:10.1051/0004-6361/201527034. S2CID 118944156. A72.
5. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
6. 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. S2CID 119257644.
7. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
8. Famaey, B.; et al. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics. 430: 165–186. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. S2CID 17804304.
9. "37 Com". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-07-16.
10. Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy. 18 (3): 214. Bibcode:1987JHA....18..209W. doi:10.1177/002182868701800305. S2CID 118445625.
11. Lambert, D. L.; Ries, L. M. (Aug 15, 1981). "Carbon, nitrogen, and oxygen abundances in G and K giants". Astrophysical Journal. 248: 228–248. Bibcode:1981ApJ...248..228L. doi:10.1086/159147.