HD 106112

HD 106112, also known as CO Camelopardalis, is a star in the constellation Camelopardalis. It has an apparent magnitude of about 5.1, meaning that it is just barely visible to the naked eye. Based upon parallax measurements made by the Hipparcos spacecraft, this star is around 177 light years away from the Sun.[2]

HD 106112

A visual band light curve for HD 106112, adapted from Steinbring et al. (1995)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Camelopardalis
Right ascension 12h 12m 11.94409s[2]
Declination +77° 36′ 58.4696″[2]
Apparent magnitude (V) 5.155[3]
Characteristics
Spectral type kA6hF0mF0 (III)[4]
U−B color index +0.10[5]
B−V color index +0.31[5]
Variable type Ellipsoidal
Astrometry
Radial velocity (Rv)0.40[6] km/s
Proper motion (μ) RA: 11.40[2] mas/yr
Dec.: 20.20[2] mas/yr
Parallax (π)29.96 ± 0.24 mas[2]
Distance108.9 ± 0.9 ly
(33.4 ± 0.3 pc)
Absolute magnitude (MV)1.62[7]
Orbit[6]
Period (P)1.271 days
Eccentricity (e)0.01
Periastron epoch (T)2436763.91
Argument of periastron (ω)
(secondary)		163°
Semi-amplitude (K1)
(primary)		64.00 km/s
Details
A
Luminosity8.02[8] L☉
Surface gravity (log g)3.98[9] cgs
Temperature7,122[9] K
Rotational velocity (v sin i)64.1[9] km/s
Other designations
CO Cam, BD+78°412, HD 106112, HIP 59504, SAO 7522, HR 4646, GC 16672[3]
Database references
SIMBADdata

HD 106112's spectral type shows that it is an A-type giant star.[10] HD 106112 is also an Am star,[3] also known as a metallic-line star. These types of stars have spectra indicating varying amounts of metals, like iron.[11]

Observations of the stars spectrum reveal a periodic Doppler shift. This means that HD 106112 is a spectroscopic binary with a period of 1.271 days and an eccentricity of 0.01.[6] In fact, the two stars orbit so closely that they distort each other into an ellipsoidal shape through gravity, thereby forming a rotating ellipsoidal variable system. However, almost no information is known about the companion star.

References
  1. Steinbring, E.; Hube, D. P.; Martin, B. E. (April 1995). "The Ellipsoidal Variability of HR4646". Information Bulletin on Variable Stars. 4184: 1. Bibcode:1995IBVS.4184....1S. Retrieved 9 November 2021.
  2. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  3. "iot Del". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 15 January 2016.
  4. Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Robinson, P. E. (2003). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I". The Astronomical Journal. 126 (4): 2048. arXiv:astro-ph/0308182. Bibcode:2003AJ....126.2048G. doi:10.1086/378365. S2CID 119417105.
  5. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. Pourbaix, D.; et al. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID 119387088.
  7. Stateva, I.; Iliev, I. Kh.; Budaj, J. (2012). "Abundance analysis of Am binaries and search for tidally driven abundance anomalies - III. HD 116657, HD 138213, HD 155375, HD 159560, HD 196544 and HD 204188". Monthly Notices of the Royal Astronomical Society. 420 (2): 1207–1216. arXiv:1111.0978. Bibcode:2012MNRAS.420.1207S. doi:10.1111/j.1365-2966.2011.20108.x. S2CID 118574727.
  8. McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (2012). "Fundamental parameters and infrared excesses of Hipparcos stars". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. S2CID 118665352.
  9. Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377
  10. Allen, J. S. "The Classification of Stellar Spectra". UCL Department of Physics and Astronomy: Astrophysics Group. Retrieved 1 January 2014.
  11. David Darling. "Am star, The Internet Encyclopedia of Science". Archived from the original on 4 August 2017. Retrieved 14 August 2008.
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