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RU Ursae Minoris
RUUMiLightCurve.png
A light curve for RU Ursae Minoris, plotted from TESS data [1]
Observation data
Epoch J2000       Equinox J2000
Constellation Ursa Minor
Right ascension 13h 38m 56.8159s [2]
Declination +69° 48′ 11.1694″ [2]
Apparent magnitude (V) 10 - 10.66 [3]
Characteristics
Spectral type F0 IV/V + K5V
Astrometry
Proper motion (μ) RA: 17.253±0.056 [2]  mas/ yr
Dec.: −5.004±0.049 [2]  mas/ yr
Parallax (π)3.5007 ± 0.0317  mas [2]
Distance932 ± 8  ly
(286 ± 3  pc)
Absolute magnitude (MV)2.45 ± 0.12 (A)
5.88 ± 0.19 (B) [4]
Absolute bolometric
magnitude
 (Mbol)
2.48 ± 0.12 (A)
5.37 ± 0.19 (B) [4]
Orbit [4]
Period (P)0.52492555(1) d
Semi-major axis (a)3.99 ± 0.02 M
Inclination (i)82.33 ± 0.05°
Periastron epoch (T)JD 2441596.33645(6)
Details [4]
RU UMi A
Mass2.32 ± 0.07  M
Radius1.78 ± 0.02  R
Luminosity7.63 ± 0.87  L
Surface gravity (log g)4.30 ± 0.02  cgs
Temperature7200 ± 200  K
RU UMi B
Mass0.76 ± 0.02  M
Radius1.14 ± 0.02  R
Luminosity0.54 ± 0.10  L
Surface gravity (log g)4.20 ± 0.02  cgs
Temperature4630 ± 200  K
Other designations
BD+70°751, Gaia DR2 1686621699950649344, TYC 4402-504-1, 2MASS J13385680+6948111 [5]
Database references
SIMBAD data

RU Ursae Minoris is a binary star system in the constellation Ursa Minor. Its apparent magnitude ranges from 10 to 10.66 over 0.52 days as one star passes in front of the other relative to observers on Earth. [3] Its component stars were calculated to be a primary star of spectral type F0IV/V and a secondary of spectral type K5V, both slightly more luminous than their spectral types indicate. The system is semidetached, as the secondary star is filling its Roche lobe and transferring matter to the primary. [6] The primary is between 2.2 and 2.3 times as massive as the Sun, with 1.8 times its radius and around 8 times its luminosity. The secondary has around 0.72 times the Sun's mass, 1.1 times its radius and between 0.58 and 0.86 times its luminosity. [7]

The period the two take to orbit each other is decreasing very slowly (by approximately 0.15 seconds per year), suggesting the components are moving closer and will become a contact binary. [7]

References

  1. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  2. ^ a b c d e 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.
  3. ^ a b Watson, Christopher (4 January 2010). "RU Ursae Minoris". AAVSO Website. American Association of Variable Star Observers. Retrieved 18 July 2015.
  4. ^ a b c d Lee, Jae Woo; Kim, Chun-Hwey; Kim, Seung-Lee; Lee, Chung-Uk; Han, Wonyong; Koch, Robert H. (2008). "A Long-term Photometric Study of the Near-contact Binary RU Ursae Minoris". Publications of the Astronomical Society of the Pacific. 120 (869): 720. Bibcode: 2008PASP..120..720L. doi: 10.1086/589976.
  5. ^ "RU Ursae Minoris". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-07.
  6. ^ Manimanis, V. N.; Niarchos, P. G. (2001). "A Photometric study of the near-contact system RU Ursae Minoris". Astronomy and Astrophysics. 369 (3): 960–64. Bibcode: 2001A&A...369..960M. doi: 10.1051/0004-6361:20010178.
  7. ^ a b Zhu, Li-Ying; Qian, Sheng-Bang; Xiang, Fu-Yuan (2006). "The Near-Contact Binary RU Ursae Minoris". Publications of the Astronomical Society of Japan. 58 (2): 361–66. Bibcode: 2006PASJ...58..361Z. doi: 10.1093/pasj/58.2.361.