W Ursae Minoris

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W Ursae Minoris

A visual band light curve for W Ursae Minoris, adapted from Devinney et al. (1970)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation
Ursa Minor
Right ascension 16h 08m 27.2728s[2]
Declination +86° 11′ 59.5511″[2]
Apparent magnitude (V) 8.51-9.59[3]
Characteristics
Spectral type A1/2V[4] (A3V + G2IV)[5]
Variable type Algol[3]
Distance
1,350 ± 20 ly
(414 ± 5 pc)
Semi-amplitude
(K1)
(primary)		90.4±1.5 km/s
Semi-amplitude (K2)
(secondary)		196.6±2.6 km/s
Details
Myr
HIP 79069, SAO 2692[7]
Database references
SIMBADdata

W Ursae Minoris is an

eclipsing binary star system in the constellation Ursa Minor. Its apparent magnitude ranges from 8.51 to 9.59 over 1.7 days as one star passes in front of the other relative to observers on Earth.[3]
The combined spectrum of the system is A1/2V.

Slight changes in the orbital period suggest that there is a third component of the multiple star system, most likely a red dwarf, with an orbital period of 62.2±3.9 years.[8] Another study suggests that the third star has a minimum mass of 0.49 M☉ and an orbit of about 72 years.[6]

The two main stars are currently thought to have masses of 3.2 M☉ and 1.4 M☉ respectively. Models of their evolution and mass transfer suggest that the secondary star was initially the more massive of the two and that it has lost mass to what is now the primary as well as losing mass completely from the system. The two stars have also spiralled in towards each other over the few hundred million years since they formed.[6]

References

  1. S2CID 121750637
    .
  2. ^
    doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  3. ^ a b c Watson, Christopher (4 January 2010). "W Ursae Minoris". AAVSO Website. American Association of Variable Star Observers. Retrieved 18 July 2015.
  4. Bibcode:1975MmRAS..79..131H
    .
  5. doi:10.1093/mnras/stz3363
    .
  6. ^
    S2CID 208920968
    .
  7. ^ "W UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-07.
  8. doi:10.1111/j.1365-2966.2007.12652.x
    .
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