12 Camelopardalis

12 Camelopardalis is a binary star in the northern circumpolar constellation of Camelopardalis, located 700 light years away from the Sun as determined from parallax measurements.[1] It forms a double star with 11 Camelopardalis, which is only 3 arcminutes away. The system has the variable star designation BM Camelopardalis; 12 Camelopardalis is the Flamsteed designation. It is just visible to the naked eye, appearing as a dim, orange-hued star with an apparent visual magnitude of 6.08.[2] The system is moving closer to the Earth with a heliocentric radial velocity of −2 km/s.[2]

12 Camelopardalis

12 Camelopardalis (center) in optical light
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Camelopardalis
Right ascension  05h 06m 12.13609s[1]
Declination +59° 01′ 16.8261″[1]
Apparent magnitude (V) 6.08[2]
Characteristics
Evolutionary stage giant
Spectral type K0 IIIe[3]
B−V color index 1.112±0.009[2]
Variable type RS CVn[4]
Astrometry
Radial velocity (Rv)−1.92±0.27[2] km/s
Proper motion (μ) RA: −2.264[1] mas/yr
Dec.: −26.949[1] mas/yr
Parallax (π)4.6513 ± 0.0706[1] mas
Distance700 ± 10 ly
(215 ± 3 pc)
Absolute magnitude (MV)−0.332[5]
Details
12 Cam A
Mass1.1[6] M☉
Radius23.08+0.75
−1.34[1] R☉
Luminosity212±4[1] L☉
12 Cam B
Mass0.6[6] M☉
Other designations
12 Cam, BM Cam, BD+58°805, HD 32357, HIP 23743, HR 1623, SAO 25003, CCDM 05062+5900, WDS J05061+5858B[7]
Database references
SIMBADdata

Abt et al. (1969) determined this to be a single-lined spectroscopic binary system and computed an orbital solution with a period of 80.17 days and an eccentricity of 0.35.[8] However, what appeared to be an ellipticity effect with a period of 79.93±0.05 d was found, which was inconsistent with the computed orbit, and the lack of modulation of the amplitude did not fit with the large orbital eccentricity. Hall et al. (1995) made additional measurements, finding an orbital period of 80.9 days and an eccentricity that is statistically indistinguishable from zero.[6]

The visible component is an evolved giant star with a stellar classification of K0 IIIe,[3] showing strong emission lines.[8] It is an RS Canum Venaticorum variable and its brightness varies by 0.14 magnitudes with a period of 82.9 days due to starspots.[4] The star is most likely rotating in synchronous manner with its orbital period.[6] The magnetic activity has two overlapping cycles of 14.8 and 8.5 years, with the activity occurring at two latitudes.[9] BM Cam emits X-rays and is the designated X-ray source 1H 0501+592.[10] It has been detected by HEAO 1, the Einstein Observatory, and ROSAT.

References
  1. 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.
  2. 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.
  3. 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.
  4. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S.
  5. Böhm-Vitense, Erika; et al. (December 2000), "Ultraviolet Emission Lines in BA and Non-BA Giants", The Astrophysical Journal, 545 (2): 992–999, Bibcode:2000ApJ...545..992B, doi:10.1086/317850.
  6. Hall, D. S.; et al. (March 1995), "A spectroscopic and photometric study of 12 BM Camelopardalis", Astronomical Journal, 109 (3): 1277–1288, Bibcode:1995AJ....109.1277H, doi:10.1086/117360.
  7. "12 Cam". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-04-15.
  8. Abt, Helmut A.; et al. (August 1969), "12 Cam., Calcium emission in giant binaries.", Astrophysical Journal, 157: 717, Bibcode:1969ApJ...157..717A, doi:10.1086/150108.
  9. Zboril, M.; Messina, S. (April 2009), "Magnetic activity on 12 Cam and 29 Dra from long-term photometry", Astronomische Nachrichten, 330 (4): 377, Bibcode:2009AN....330..377Z, doi:10.1002/asna.200811190.
  10. Wood, K. S.; Meekins, J. F.; Yentis, D. J.; Smathers, H. W.; McNutt, D. P.; Bleach, R. D. (Dec 1984), "The HEAO A-1 X-ray source catalog", Astrophysical Journal Supplement Series, 56 (12): 507–649, Bibcode:1984ApJS...56..507W, doi:10.1086/190992.
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