DM Ursae Majoris

Visual band light curves for DM Ursae Majoris, adapted from Mohin et al. (1985)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension 10h 55m 43.544s[2]
Declination +60° 28′ 09.72″[2]
Apparent magnitude (V) 9.29[3]
Characteristics
Spectral type K0III-IV[4] (K0IV + K5V)[5]
B−V color index 1.014±0.026[3]
Variable type RS CVn[6]
Astrometry
Radial velocity (Rv)−6.9±1.2[7] km/s
Proper motion (μ) RA: −37.912 mas/yr[2]
Dec.: −7.566 mas/yr[2]
Parallax (π)5.3862 ± 0.0157 mas[2]
Distance606 ± 2 ly
(185.7 ± 0.5 pc)
Absolute magnitude (MV)3.65[3]
Orbit[7]
Period (P)7.4920±0.0009 d
Eccentricity (e)0.0 (assumed)
Inclination (i)40[8]°
Periastron epoch (T)2,443,881.4±0.1 JD
Argument of periastron (ω)
(secondary)		0.0 (assumed)°
Semi-amplitude (K1)
(primary)		27.6 km/s
Details
Primary
Mass~1.2[5] M☉
Radius6.00[4] R☉
Luminosity4.24[3] L☉
Temperature4,500[4] K
Secondary
Mass~0.7[5] M☉
Other designations
2A 1052+606, DM UMa, BD+61°1211, HIP 53425, SAO 15338, PPM 17646[9]
Database references
SIMBADdata

DM Ursae Majoris is a binary star system in the northern circumpolar constellation of Ursa Major, abbreviated DM UMa. It is sometimes identified by the Bonner Durchmusterung catalogue designation BD +61 1211; DM UMa is the variable star designation. The system has a combined apparent visual magnitude of 9.29,[3] which is too faint to be visible to the naked eye. Based on parallax measurements, the system is located at a distance of approximately 606 light years from the Sun,[2] but it is drifting closer with a heliocentric radial velocity of −7 km/s.[7]

In 1978, the X-ray source designated 2A 1052+606 was initially included in the 2A catalogue of observations by the Ariel 5 satellite.[10] The approximate position of this source was determined using the HEAO-1 satellite, then W. Liller matched it with the candidate star SAO 015338 (later DM UMa). He determined the spectra matches a K-type star with strong H-alpha emission lines.[11] In 1979, this object was shown to be an RS Canum Venaticorum variable (RS CVn) by D. Crampton and associates, which indicated this is a close binary star system where one of the components has an active chromosphere with star spots.[7] DM UMa was the first RS CVn variable to be so classified based on its X-ray emission.[12]

Radial velocity measurements demonstrated an orbital period of about 7.5 days. A mass function of 0.016 M☉ suggested the system is being viewed from a low inclination, close to pole-on.[7] The system showed variations in emission lines on a time scale of a day.[13] A photometric light curve was generated by R. A. Kimble and associates in 1981, showing strong variability within each orbital period.[5] A model fit to the light curve indicated the star has an extensive distribution of star spots, with regions of enhanced spot activity toward and away from the companion. It is one of the few variables of this class that show a continual emission of H-alpha, although this varies by a factor of three over the course of an orbit.[12]

This is a single-lined spectroscopic binary[5] with the spectra matching a stellar classification of K0III-IV.[4] The secondary is at least 1.5 magnitudes fainter than the primary, so the contribution of the former to the luminosity is no more than 20%.[12] The observed properties of the system can be modeled by a combination of a subgiant primary of class K0IV with a K5V main sequence secondary.[5]

References

  1. ↑ Mohin, S.; Raveendran, A. V.; Mekkaden, M. V.; Hall, D. S.; Henry, G. W.; Lines, R. D.; Fried, R. E.; Louth, H.; Stelzer, H. J. (October 1985). "Evolution of Starspot Regions in DM UMa". Astrophysics and Space Science. 115 (2): 353–368. Bibcode:1985Ap&SS.115..353M. doi:10.1007/BF00653812. S2CID 119914476. Retrieved 6 October 2022.
  2. 1 2 3 4 5 6 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  3. 1 2 3 4 5 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.
  4. 1 2 3 4 Strassmeier, Klaus G. (September 2009), "Starspots", The Astronomy and Astrophysics Review, 17 (3): 251–308, Bibcode:2009A&ARv..17..251S, doi:10.1007/s00159-009-0020-6.
  5. 1 2 3 4 5 6 Kimble, R. A.; et al. (December 1981), "Discovery of a large-amplitude photometric wave in the RS CVn binary BD +61 1211 (=DM UMA) and constraints on starspot models for the observed variation", Astrophysical Journal, 251: 585–590, Bibcode:1981ApJ...251..585K, doi:10.1086/159502.
  6. ↑ Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  7. 1 2 3 4 5 Crampton, D.; et al. (December 1979), "The RS CVn system BD +61 1211 = 2A 1052+60.6", Astrophysical Journal, 234: 993–996, Bibcode:1979ApJ...234..993C, doi:10.1086/157583, S2CID 120565755.
  8. ↑ Hatzes, Artie P. (January 1995), "Spot and Chromospheric Activity on the RS CVN Star DM Ursae Majoris", Astronomical Journal, 109: 350, Bibcode:1995AJ....109..350H, doi:10.1086/117280.
  9. ↑ "DM UMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2022-10-01.
  10. ↑ Cooke, B. A.; et al. (February 1978), "The Ariel V (SSI) catalogue of high galactic latitude (|b| > 10°) X-ray sources", Monthly Notices of the Royal Astronomical Society, 182 (3): 489–515, Bibcode:1978MNRAS.182..489C, doi:10.1093/mnras/182.3.489.
  11. ↑ Liller, W.; et al. (February 1978), Marsden, B. G. (ed.), "2A 1052+606 = SAO 015338?", IAU Circular, 3176: 2, Bibcode:1978IAUC.3176....2L.
  12. 1 2 3 Rosario, M. J.; et al. (April 2009), "Spot activity in the RS CVn binary DM Ursae Majoris", Monthly Notices of the Royal Astronomical Society, 394 (2): 872–881, Bibcode:2009MNRAS.394..872R, doi:10.1111/j.1365-2966.2008.14372.x, S2CID 123218100.
  13. ↑ Charles, P.; et al. (December 1979), "X-ray and optical variability in 2A1052+606-a new RS CVn-type system", Nature, 282 (5740): 691–692, Bibcode:1979Natur.282..691C, doi:10.1038/282691a0, S2CID 4315279.

Further reading

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