VV Ursae Majoris is a binary star system in the northern circumpolar constellation of Ursa Major, abbreviated VV UMa. It is a variable star system with a brightness that cycles around an apparent visual magnitude of 10.19,[3] making it too faint to be visible to the naked eye. The system is located at a distance of approximately 1,500 light years based on parallax measurements.[2]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 09h 38m 06.719s[2] |
| Declination | +56° 01′ 07.29″[2] |
| Apparent magnitude (V) | 10.19[3] |
| Characteristics | |
| Spectral type | A1.5–2V[4] + G5IV[5] |
| Variable type | Semidetached Algol[6] |
| Astrometry | |
| Proper motion (μ) | RA: −18.536 mas/yr[2] Dec.: 3.254 mas/yr[2] |
| Parallax (π) | 2.177 ± 0.0394 mas[2] |
| Distance | 1,500 ± 30 ly (459 ± 8 pc) |
| Absolute magnitude (MV) | 1.87[4] |
| Orbit | |
| Period (P) | 0.68735545 d[5] |
| Semi-major axis (a) | 3.54[5]" (4.87 R☉[4]) |
| Eccentricity (e) | 0.0[7] |
| Inclination (i) | 82.07±0.3[4]° |
| Periastron epoch (T) | 2,428,925.637 JD[7] |
| Semi-amplitude (K1) (primary) | 59.6[7] km/s |
| Details | |
| Primary | |
| Mass | 0.97[5] M☉ |
| Radius | 1.35[5] R☉ |
| Luminosity | 11.2[5] L☉ |
| Surface gravity (log g) | 4.37[4] cgs |
| Temperature | 9,090[5] K |
| Secondary | |
| Mass | 0.29[5] M☉ |
| Radius | 0.96[5] R☉ |
| Luminosity | 0.42[5] L☉ |
| Surface gravity (log g) | 4.00[4] cgs |
| Temperature | 4,740[5] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
This star was found to be variable by H. K. Gitz in 1936 based on photographic plates taken in Moscow, then S. Kaho published an ephemeris in 1939 using observed minima.[9] In 1950, O. Struve computed the orbital elements for a single-lined spectroscopic binary system with a short orbital period of just 17 hours. He found a stellar classification of A0V for the primary component.[10] P. Broglia and P. Conconi analyzed the light curve of the system in 1977, and determined this to be a semidetached binary with the secondary component being significantly less massive than the primary.[11] In 1996, V. Simon found a periodic variation in the system minima with a cycle length of 22 years. He proposed that this variation is being driven by a third component in the system.[9]
This is an eclipsing binary;[4] a semi-detached Algol-type system.[6] The best fit spectral type for the primary component is A1.5–2V, matching an A-type main-sequence star. The secondary is a cooler, overluminous, late G-type star;[4] it is a slightly evolved subgiant star that is filling its Roche lobe.[11] The system displays an intrinsic low amplitude variability, which is probably coming from the primary.[4] Multiple pulsation periods have been detected.[12] There is no evidence of an infrared excess.[4]
The light-travel time effect provides information about the properties of the purported third component in the system. It has 0.787 times the mass of the Sun and is orbiting at a distance of 10.75 AU from the inner pair with an eccentricity of 0.35 and a period of 23.22±0.17 years.[13]
References
Further reading
- Ulas, Burak; et al. (August 2007), "The Algol-type Binary VV UMa: New VRI Photometry and Search for Pulsations", JENAM-2007, "Our non-stable Universe", held 20–25 August 2007 in Yerevan, Armenia, p. 21, Bibcode:2007jena.confE..21U, 21-21.
- Kim, S. -L.; et al. (February 2005), "On a short-periodic pulsating component in the Algol-type eclipsing binary system VV UMa", Information Bulletin on Variable Stars, 5598: 1, Bibcode:2005IBVS.5598....1K.
- Lázaro, C.; et al. (August 2001), "uvbyβ photometry of the short-period binary VV Ursae Majoris", Monthly Notices of the Royal Astronomical Society, 325 (2): 617–630, Bibcode:2001MNRAS.325..617L, doi:10.1046/j.1365-8711.2001.04437.x.
- Simon, Vojtech (1997), Leung, Kam-Ching (ed.), "Period Changes of the Binary VV UMa: Light-Time Effect or Magnetic Activity", The Third Pacific Rim Conference on Recent Development on Binary Star Research. Proceedings of a conference sponsored by Chiang Mai University, Thai Astronomical Society and the University of Nebraska-Lincoln held in Chiang Mai, Thailand, 26 October -1 November 1995, ASP Conference Series, vol. 130, p. 277, Bibcode:1997ASPC..130..277S.
- Simon, V. (July 1996), "The cyclic period changes of the close binary VV Ursae Majoris", Astronomy and Astrophysics, 311: 915–918, Bibcode:1996A&A...311..915S.
- Wunder, E. (March 1995), "The First Period Change Discovered in the Bright Algol System UV Leonis", Information Bulletin on Variable Stars, 4179: 1, Bibcode:1995IBVS.4179....1W.
- Horák, T. (1966), "New elements of the eclipsing variables TW Draconis, RW Tauri and KR Cygni and the influence of the rectification of the light curve upon the elements VV Ursae Maioris", Bulletin of the Astronomical Institute of Czechoslovakia, 17: 272, Bibcode:1966BAICz..17..272H.
- Wilson, Robert E. (June 1965), "A possible extended atmosphere in the eclipsing system W UMa", Astronomical Journal, 70: 368, Bibcode:1965AJ.....70..368W, doi:10.1086/109749.