RU Ursae Minoris

RU Ursae Minoris

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
SIMBADdata

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]

  1. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference Gaia DR2 was invoked but never defined (see the help page).
  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. ^ Cite error: The named reference Simbad was invoked but never defined (see the help page).
  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.