RR Ursae Minoris

RR Ursae Minoris
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Minor
Right ascension 14h 57m 35.01625s[1]
Declination +65° 55′ 56.9143″[1]
Apparent magnitude (V) 4.44 - 4.85[2]
Characteristics
Spectral type M4.55 III[3]
B−V color index 1.590±0.017[4]
Variable type SRb[5]
Astrometry
Radial velocity (Rv)6.21±0.30[6] km/s
Proper motion (μ) RA: −82.191[1] mas/yr
Dec.: +26.981[1] mas/yr
Parallax (π)10.0206 ± 0.6341[1] mas
Distance330 ± 20 ly
(100 ± 6 pc)
Absolute magnitude (MV)−1.11[4]
Orbit[7]
Period (P)748.9 d
Eccentricity (e)0.13±0.05
Inclination (i)79.6±2.4[8]°
Longitude of the node (Ω)48.0±2.5[8]°
Periastron epoch (T)2,444,419±46 JD
Argument of periastron (ω)
(secondary)		212±22°
Semi-amplitude (K1)
(primary)		8.3±0.3 km/s
Details
Mass1.15±0.1[9] M☉
Radius103[10] R☉
Luminosity931.23[4] L☉
Surface gravity (log g)0.00[11] cgs
Temperature3,464[12] K
Other designations
AAVSO 1456+66, RR UMi, BD+66° 878, FK5 554, HD 132813, HIP 73199, HR 5589, SAO 16558[13]
Database references
SIMBADdata

RR Ursae Minoris, or RR UMi, is a binary star[11] system in the northern circumpolar constellation of Ursa Minor. It can be viewed with the naked eye, typically having a apparent visual magnitude of around 4.710.[8] Based upon an annual parallax shift of 10.0 mas[1] as seen from Earth's orbit, it is located 330 light years away. The system is moving further from the Sun with a heliocentric radial velocity of +6 km/s.[6]

This is a single-lined spectroscopic binary system with an orbital period of 2.05 years and an eccentricity of 0.13. The a sin i value is 8.4×107 km (0.56 AU),[7] where a is the semimajor axis and i is the orbital inclination to the line of sight from the Earth. The system is a source for X-ray and far-UV emission, with the latter most likely coming from the companion.[11]

The primary component is an aging red giant star on the asymptotic giant branch[11] with a stellar classification of M4.5 III.[3] It is a semiregular variable of subtype SRb,[5] ranging from magnitude 4.44 to 4.85 over a period of 43.3 days.[2] The interferometry-measured angular diameter of the primary component is 9.6±0.7 mas,[14] which, at its estimated distance, equates to a physical radius of about 103 times the radius of the Sun.[10]

References

  1. 1 2 3 4 5 6 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.
  2. 1 2 Otero, Sebastian Alberto (16 November 2009). "RR Ursae Minoris". AAVSO Website. American Association of Variable Star Observers. Retrieved 18 May 2014.
  3. 1 2 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. 1 2 3 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971 [astro-ph.GA]. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. Cite uses deprecated parameter |class= (help)
  5. 1 2 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.
  6. 1 2 de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048 [astro-ph.SR], Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61. Cite uses deprecated parameter |class= (help)
  7. 1 2 Batten, A. H.; Fletcher, J. M. (July 1986). "A revised spectroscopic orbit for RR Ursae Minoris". Publications of the Astronomical Society of the Pacific. 98: 647–650. Bibcode:1986PASP...98..647B. doi:10.1086/131808.
  8. 1 2 3 Ren, Shulin; Fu, Yanning (March 2013), "Hipparcos Photocentric Orbits of 72 Single-lined Spectroscopic Binaries", The Astronomical Journal, 145 (3): 7, Bibcode:2013AJ....145...81R, doi:10.1088/0004-6256/145/3/81, 81.
  9. ↑ Halabi, Ghina M.; Eid, Mounib El (2015). "Exploring masses and CNO surface abundances of red giant stars". Monthly Notices of the Royal Astronomical Society. 451 (3): 2957. arXiv:1507.01517. Bibcode:2015MNRAS.451.2957H. doi:10.1093/mnras/stv1141.
  10. 1 2 Lang, Kenneth R. (2006). "Astrophysical formulae". Astronomy and astrophysics library. 1 (3rd ed.). Birkhäuser. ISBN 3-540-29692-1. The radius (R*) is given by:
  11. 1 2 3 4 Ortiz, Roberto; Guerrero, Martín A. (2016). "Ultraviolet emission from main-sequence companions of AGB stars". Monthly Notices of the Royal Astronomical Society. 461 (3): 3036. arXiv:1606.09086. Bibcode:2016MNRAS.461.3036O. doi:10.1093/mnras/stw1547.
  12. ↑ Soubiran, Caroline; et al. (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics. 591: A118. arXiv:1605.07384. Bibcode:2016A&A...591A.118S. doi:10.1051/0004-6361/201628497.
  13. ↑ "RR UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 7, 2018.
  14. ↑ Richichi, A.; et al. (February 2005). "CHARM2: An updated Catalog of High Angular Resolution Measurements". Astronomy and Astrophysics. 431: 773–777. Bibcode:2005A&A...431..773R. doi:10.1051/0004-6361:20042039.
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