24 Comae Berenices

Map showing location of 24 Comae Berenices
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Coma Berenices
A
Right ascension 12h 35m 07.76130s[1]
Declination +18° 22′ 37.4133″[1]
Apparent magnitude (V) 5.03[2]
B
Right ascension 12h 35m 06.34558s[1]
Declination +18° 22′ 37.5320″[1]
Apparent magnitude (V) 6.57[2]
Characteristics
A
Spectral type K0II-III[3]
B−V color index 1.152±0.018[2]
B
Evolutionary stage A9V[3]
B−V color index 0.265±0.015[2]
Astrometry
A
Radial velocity (Rv)+3.03±0.10[2] km/s
Proper motion (μ) RA: −3.719[1] mas/yr
Dec.: +23.106[1] mas/yr
Parallax (π)8.5745 ± 0.1996 mas[1]
Distance380 ± 9 ly
(117 ± 3 pc)
Absolute magnitude (MV)0.30[4]
B
Radial velocity (Rv)+4.90±0.50[2] km/s
Proper motion (μ) RA: −2.320[1] mas/yr
Dec.: +21.236[1] mas/yr
Parallax (π)8.8346 ± 0.0695 mas[1]
Distance369 ± 3 ly
(113.2 ± 0.9 pc)
Orbit[5]
PrimaryBa
CompanionBb
Period (P)7.336673±0.000087 d
Semi-major axis (a)1.007±0.037 mas
Eccentricity (e)0.2585±0.0012
Inclination (i)61.40±3.89°
Longitude of the node (Ω)136.17±2.86°
Periastron epoch (T)2,459,361.967±0.011 JD
Argument of periastron (ω)
(primary)		302.33±0.28°
Semi-amplitude (K1)
(primary)		68.16±0.09 km/s
Semi-amplitude (K2)
(secondary)		81.28±0.20 km/s
Details
A
Mass4.40[6] M☉
Radius19.95+0.69
−2.58[1] R☉
Luminosity173.3±4.6[1] L☉
Surface gravity (log g)2.50[4] cgs
Temperature4,688+337
−79[1] K
Metallicity [Fe/H]−0.09[7] dex
B
Mass1.838/1.541[5] M☉
Radius2.28/1.70[5] R☉
Luminosity15.6/7.2[5] L☉
Surface gravity (log g)3.86/4.09[5] cgs
Temperature7630/7180[5] K
Metallicity [Fe/H]0.54[8] dex
Rotational velocity (v sin i)14.5/14.2[5] km/s
Other designations
24 Com, BD+19°2584, FK5 473, WDS 02338-2814
A: NSV 5748, GC 17147, HD 109511, HIP 61418, HR 4792, SAO 100160[9]
B: GC 17146, HD 109510, HIP 61415, HR 4791, SAO 100159[10]
Database references
SIMBADA
B

24 Comae Berenices is a triple star system in the northern constellation of Coma Berenices. It is visible to the naked eye, with the brightest component being an orange-hued star with an apparent visual magnitude of 5.03.[2] The system is located at a distance of approximately 269 light-years from the Sun based on parallax, and is drifting further away with radial velocities of 3–5 km/s.[2]

This system can be resolved in a telescope as a pair of stars with an angular separation of 20.2″ along a position angle of 272°, as of 2018.[11] They share a common motion through space and thus appear to be physically associated,[12] with a wide projected separation of 1,400 AU or greater.[13] If they are bound in an orbit, the estimated period is approximately 28,000 years.[6]

The brighter member of this system is an aging giant or bright giant star with a stellar classification of K0II-III.[3] It has exhausted the supply of hydrogen at its core and expanded to 20[1] times the girth of the Sun. This is a suspected variable that has been recorded ranging in brightness from magnitude 4.98 down to 5.06.[14] The star is radiating 173[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,688 K.[1]

The fainter component at magnitude 6.57[2] is a double-lined spectroscopic binary with an orbital period of 7.33 days and an eccentricity of 0.26.[12] The primary member of this pair is an A-type main-sequence star with a stellar classification of A9V.[3] It is a metallic-lined Am star[15] with 2.2 times the radius of the Sun.[5] The stars radiate about 16 and 7 times the Sun's luminosity from its photosphere, respectively, at effective temperatures of 7,630 and 7180 K, respectively.[5] Both have relatively low projected rotational velocity of around 14 km/s,[5] and it is suspected the rotations of this binary system may be synchronized.[8] The system is a source for X-ray emission, which is most likely coming from the secondary.[16]

References

  1. ^ a b c d e f g h i j k l m n o p 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.
  2. ^ a b c d e f g h i 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.
  3. ^ a b c d Yoss, K. M.; Griffin, R. F. (September 1997), "Radial Velocities and DDO, BV Photometry of Henry Draper G5-M Stars Near the North Galactic Pole", Journal of Astrophysics and Astronomy, 18 (2–3): 161, Bibcode:1997JApA...18..161Y, doi:10.1007/BF02714877, S2CID 123221180.
  4. ^ a b McWilliam, Andrew (1990), "High-Resolution Spectroscopic Survey of 671 GK Giants. I. Stellar Atmosphere Parameters and Abundances", The Astrophysical Journal Supplement Series, 74: 1075, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527.
  5. ^ a b c d e f g h i j Lester, Kathryn V.; et al. (2022), "Visual Orbits of Spectroscopic Binaries with the CHARA Array. IV. HD 61859, HD 89822, HD 109510, and HD 191692", The Astronomical Journal, 164 (6): 228, arXiv:2209.09993, Bibcode:2022AJ....164..228L, doi:10.3847/1538-3881/ac9385, S2CID 252408703.
  6. ^ a b Tokovinin, A. (September 2008), "Comparative statistics and origin of triple and quadruple stars", Monthly Notices of the Royal Astronomical Society, 389 (2): 925–938, arXiv:0806.3263, Bibcode:2008MNRAS.389..925T, doi:10.1111/j.1365-2966.2008.13613.x, S2CID 16452670.
  7. ^ Malagnini, M. L.; et al. (2000), "Observations and Atmospheric Parameters of Super-Metal-rich Candidates", The Publications of the Astronomical Society of the Pacific, 112 (777): 1455, Bibcode:2000PASP..112.1455M, doi:10.1086/317714.
  8. ^ a b Stickland, D. J. (1973), "On the atmospheric abundances of seven Am SB2 systems", Monthly Notices of the Royal Astronomical Society, 161 (2): 193, Bibcode:1973MNRAS.161..193S, doi:10.1093/mnras/161.2.193.
  9. ^ "24 Com A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-30.
  10. ^ "24 Com B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-30.
  11. ^ Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22.
  12. ^ a b Mayor, M.; Mazeh, T. (January 1987), "The frequency of triple and multiple stellar systems", Astronomy and Astrophysics, 171: 157−177, Bibcode:1987A&A...171..157M.
  13. ^ Abt, Helmut A. (August 1988), "Maximum Separations among Cataloged Binaries", Astrophysical Journal, 331: 922, Bibcode:1988ApJ...331..922A, doi:10.1086/166609.
  14. ^ Samus', N. N; et al. (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  15. ^ Chen, P. S.; et al. (2017), "A New Photometric Study of Ap and Am Stars in the Infrared", The Astronomical Journal, 153 (5): 218, Bibcode:2017AJ....153..218C, doi:10.3847/1538-3881/aa679a.
  16. ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677–684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.
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