24 Comae Berenices
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]
 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[1] mas |
| Distance | 380 ± 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[1] mas |
| Distance | 369 ± 3 ly (113.2 ± 0.9 pc) |
| Orbit[5] | |
| Primary | Ba |
| Companion | Bb |
| Period (P) | 7.3361±0.0005 d |
| Semi-major axis (a) | ≥ 0.04479 ± 0.00080 AU |
| Eccentricity (e) | 0.26±0.01 |
| Periastron epoch (T) | 2,444,593.29±0.04 JD |
| Argument of periastron (ω) (secondary) | 300±3° |
| Semi-amplitude (K1) (primary) | 68.7±1.0 km/s |
| Semi-amplitude (K2) (secondary) | 80.6±1.2 km/s |
| Details | |
| A | |
| Mass | 4.40[6] M☉ |
| Radius | 19.95+0.69 −2.58[1] R☉ |
| Luminosity | 173.3±4.6[1] L☉ |
| Surface gravity (log g) | 2.50[4] cgs |
| Temperature | 4,688+337 −79[1] K |
| Metallicity [Fe/H] | −0.09[7] dex |
| B | |
| Mass | 1.78/1.52[6] M☉ |
| Radius | 2.91+0.17 −0.13[1] R☉ |
| Luminosity | 23.9±0.2[1] L☉ |
| Temperature | 7,476+176 −204[1] K |
| Rotational velocity (v sin i) | < 20[8] km/s |
| Other designations | |
| 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 | |
| SIMBAD | A |
| B | |
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,[5] with a wide projected separation of 1,400 AU or greater.[12] 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.[13] 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.[5] 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[14] with 2.9 times the radius of the Sun. The star is radiating 24 times the Sun's luminosity from its photosphere at an effective temperature of 7,476 K.[1] It has a relatively low projected rotational velocity of under 20 km/s, 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.[15]
References
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- Malagnini, M. L.; Morossi, C.; Buzzoni, A.; Chavez, M. (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.
- 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.
- "24 Com A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-30.
- "24 Com B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-30.
- 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.
- Abt, Helmut A. (August 1988), "Maximum Separations among Cataloged Binaries", Astrophysical Journal, 331: 922, Bibcode:1988ApJ...331..922A, doi:10.1086/166609.
- Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (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.
- 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.
- 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.
