12 Camelopardalis
{{Short description|Star in the constellation of Camelopardalis}}
{{Starbox begin}}
{{Starbox image
| image = 250px
| caption = 12 Camelopardalis (center) in optical light
}}
{{Starbox observe
| epoch = J2000.0
| constell = Camelopardalis
| dec = {{DEC|+59|01|16.8261}}
}}
{{Starbox character
| type = giant
| variable = RS CVn
}}
{{Starbox astrometry
| radial_v = {{Val|−1.92|0.27}}
| parallax = 4.6513
| p_error = 0.0706
}}
{{Starbox detail
| source =
| component1 = 12 Cam A
| radius = {{Val|23.08|0.75|1.34}}
| gravity =
| temperature =
| metal_fe =
| rotational_velocity =
| age_myr =
| component2 = 12 Cam B
}}
{{Starbox catalog
| names = {{odlist | V=BM Cam | F=12 Cam | BD=+58°805 | HD=32357 | HIP=23743 | HR=1623 | SAO=25003 | BDS=2480 | CCDM=05062+5900 | WDS=J05061+5858B }}
}}
{{Starbox reference
| Simbad = 12+Cam
}}
{{Starbox end}}
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. 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. The system is moving closer to the Earth with a heliocentric radial velocity of −2 km/s.
File:BMCamLightCurve.png light curve for BM Camelopardalis, adapted from Zboril and Messina (2009). The main plot shows the long-term variability, and the inset plot shows the variability due to the star's rotation.]]
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. However, what appeared to be an ellipticity effect with a period of {{Val|79.93|0.05|u=days}} 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.
The visible component is an evolved giant star with a stellar classification of K0 IIIe, showing strong emission lines. Joel A. Eaton et al. discovered that the star's brightness varies, in 1980. It was given its variable star designation in 1981. 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. The star is most likely rotating in synchronous manner with its orbital period. The magnetic activity has two overlapping cycles of 14.8 and 8.5 years, with the activity occurring at two latitudes. BM Cam emits X-rays and is the designated X-ray source 1H 0501+592. It has been detected by HEAO 1, the Einstein Observatory, and ROSAT.
References
{{reflist|refs=
{{cite DR2|283927609195553792}}
{{cite simbad | title=12 Cam | accessdate=2019-04-15 }}
| last1=Keenan | first1=Philip C. | last2=McNeil | first2=Raymond C.
| title=The Perkins catalog of revised MK types for the cooler stars
| journal=Astrophysical Journal Supplement Series
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| bibcode=1989ApJS...71..245K | doi=10.1086/191373 }}
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| url=https://ibvs.konkoly.hu/pub/ibvs/1901/1902.pdf | access-date=29 December 2024}}
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| url=https://ibvs.konkoly.hu/pub/ibvs/2001/2042.pdf | access-date=29 December 2024}}
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| volume=545 | issue=2 | pages=992–999 | date=December 2000
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| title=Magnetic activity on 12 Cam and 29 Dra from long-term photometry
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| volume=330 | issue=4 | page=377 | date=April 2009
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| journal=Astrophysical Journal | postscript=.
| volume=157 | page=717 | date=August 1969
| doi=10.1086/150108 | bibcode=1969ApJ...157..717A | doi-access=free }}
| title=A spectroscopic and photometric study of 12 BM Camelopardalis
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| last2=Fekelf | first2=C. | last3=Henry | first3=G. W.
| last4=Eaton | first4=J. A. | last5=Barksdale | first5=W. S.
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| doi=10.1086/117360 | bibcode=1995AJ....109.1277H | doi-access=free }}
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| arxiv=1108.4971 | s2cid=119257644 | postscript=. }}
}}
{{Stars of Camelopardalis}}
{{DEFAULTSORT:12 Camelopardalis}}
Category:RS Canum Venaticorum variables
Category:Astronomical X-ray sources
Category:Spectroscopic binaries