UX Ursae Majoris is an Algol type binary star system in the northern circumpolar constellation of Ursa Major. It is classified as a nova-like variable star similar to DQ Herculis, although no eruptions have been reported.[11] Since its discovery in 1933, this system has been the subject of numerous studies attempting to determine its properties.[12] The combined apparent visual magnitude of UX UMa ranges from 12.57 down to 14.15.[3] The system is located at a distance of approximately 952 light years from the Sun based on parallax,[2] and is drifting further away with a radial velocity of 112 km/s.[6]
 A visual band light curve for UX Ursae Majoris, adapted from de Miguel et al. (2016).[1] The top plot shows the variation over several weeks, and the bottom plot shows the mean light curve over one orbital period. | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 13h 36m 40.953s[2] |
| Declination | +51° 54′ 49.42″[2] |
| Apparent magnitude (V) | 12.57 to 14.15[3] |
| Characteristics | |
| Spectral type | sdOB[4] + M4+[5] |
| Variable type | β Per, nova-like[3] |
| Astrometry | |
| Radial velocity (Rv) | 112.0[6] km/s |
| Proper motion (μ) | RA: −41.614 mas/yr[2] Dec.: 17.180 mas/yr[2] |
| Parallax (π) | 3.4252 ± 0.0157 mas[2] |
| Distance | 952 ± 4 ly (292 ± 1 pc) |
| Orbit[7] | |
| Period (P) | 4.72 hours |
| Semi-major axis (a) | 1.51 – 1.61 R☉ |
| Inclination (i) | 65 – 75° |
| Semi-amplitude (K1) (primary) | 113±11 km/s |
| Semi-amplitude (K2) (secondary) | 262±14 km/s |
| Details | |
| White dwarf | |
| Mass | 0.47[8] M☉ |
| Radius | 9,700[8] km |
| Surface gravity (log g) | 7.7[9] cgs |
| Temperature | 20,000[9] K |
| Donor star | |
| Mass | 0.47[8] M☉ |
| Radius | 0.496 – 0.697[9] R☉ |
| Surface gravity (log g) | −4.65 – 4.73[9] cgs |
| Accretion disk | |
| Radius | 0.488[9] R☉ |
| Temperature | 88,450±21,230[4] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
This system was found to be an eclipsing binary by the Soviet astronomer S. Belyavsky in 1933. At the time, the period of 4.73 hours was the shortest known for a binary star system.[12] M. Zverev and B. Kukarkin published elements from a light curve made from visual observations in 1937, while in 1939 V. A. Krat at Pulkovo Observatory produced a solution based on his photographic observations.[13] G. P. Kuiper in 1941 classified the star as a B3 subdwarf.[14] O. Struve in 1948 noted that the system underwent significant variations in its spectrum.[15] A. P. Linnell produced the first photoelectric light curve of the system in 1950, finding that the brightness underwent an increase just prior to the primary eclipse. He also noted that the system underwent rapid light variation.[13]
Observations of this system up to 1962 showed the period was changing: it increased up until 1953 then began decreasing. The depth of the eclipse was found to vary with wavelength, decreasing in depth with increasing wavelength possibly due to contributions by a cooler stellar component or surrounding material.[16] M. F. Walker and G. H. Herbig in 1954 suggested that the hump in the light curve is due to a hot spot. In 1974, R. E. Nather and E. L. Robinson proposed that the hot component is a white dwarf surrounded by a optically thick, orbiting disk of gas. The hot spot on the disk is formed by a stream of gas from the donor secondary star, and is the main source of the rapid flickering from the system.[14] The observed light curve can be reproduced by an orbital inclination of ~75° to the line of sight to the earth, with the white dwarf being almost completely obscured by its accretion disk.[11]
UX UMa is considered an archetypal example of nova-like variables that are always in a high accretion state, showing bright steady disks.[17] A photometric study of the system during 2015 found a cyclical signal with a mean period of 3.680 days and an amplitude of 0.44 in magnitude. This is interpreted as retrograde nodal precession of the accretion disk.[1] The infalling matter is creating a compact clump in the accretion disk. This is shielding illumination from the hot inner disk, forming a dark spot. Doppler tomography of the disk shows a spiral structure.[7] Observations during 1999 showed spectral features characteristic of an SW Sextantis variable, but at other times these features disappeared.[7]
References
Further reading
- The Eclipsing Nova-Like Variable UX Ursae Majoris, American Association of Variable Star Observers, retrieved 2022-03-03.
- Bruch, Albert (July 2020), "Miscellaneous photometric variations in cataclysmic variables: V455 And, SS Cyg, AQ Men, LQ Peg, RW Tri and UX UMa", New Astronomy, 78: 101369, arXiv:2002.06010, Bibcode:2020NewA...7801369B, doi:10.1016/j.newast.2020.101369, S2CID 211126857.
- Suleimanov, V. F.; et al. (July 2004), Tovmassian, G.; Sion, E. (eds.), "Time-resolved spectroscopy and Doppler tomography of UX UMa", Compact Binaries in the Galaxy and Beyond, Proceedings of the conference held 17-22 November, 2003 in La Paz, Baja California Sur, Revista Mexicana de Astronomía y Astrofísica (Serie de Conferencias) IAU Colloquium 194, vol. 20, p. 270, Bibcode:2004RMxAC..20..270S.
- Pratt, G. W.; et al. (March 2004), "An XMM-Newton observation of the nova-like variable UX UMa: spatially and spectrally resolved two-component X-ray emission", Monthly Notices of the Royal Astronomical Society, 348 (3): L49–L53, arXiv:astro-ph/0401176, Bibcode:2004MNRAS.348L..49P, doi:10.1111/j.1365-2966.2004.07574.x, S2CID 17367873.
- Baptista, Raymundo; et al. (August 1998), "HST spatially resolved spectra of the accretion disc and gas stream of the nova-like variable UX Ursae Majoris", Monthly Notices of the Royal Astronomical Society, 298 (4): 1079–1091, arXiv:astro-ph/9804002, Bibcode:1998MNRAS.298.1079B, doi:10.1046/j.1365-8711.1998.01712.x, S2CID 13948660.
- Wood, Janet H.; et al. (May 1995), "X-ray observations of the eclipsing nova-like variable UX UMa", Monthly Notices of the Royal Astronomical Society, 274 (1): 31–36, Bibcode:1995MNRAS.274...31W, doi:10.1093/mnras/274.1.31.
- Mason, K. O.; et al. (May 1995), "Eclipse observations of an accretion disc wind", Monthly Notices of the Royal Astronomical Society, 274 (1): 271–286, Bibcode:1995MNRAS.274..271M, doi:10.1093/mnras/274.1.271.
- Long, K. S.; et al. (September 1991), "Far Ultrviolet Observations of UX UMa", Bulletin of the American Astronomical Society, 23: 1325, Bibcode:1991BAAS...23.1325L.
- Rubenstein, E. P. (September 1991), "Orbital Period Changes of UX Ursae Majoris and other Close Binary Systems", Bulletin of the American Astronomical Society, 23: 1414, Bibcode:1991BAAS...23.1414R.
- Rubenstein, Eric P.; et al. (December 1991), "The Orbital Period Changes of UX Ursae Majoris", Publications of the Astronomical Society of the Pacific, 103: 1258, Bibcode:1991PASP..103.1258R, doi:10.1086/132945, S2CID 122080757.
- Shafter, A. W. (October 1984), "An upper limit to the mass of the white dwarf in UX Ursae Majoris", Astronomical Journal, 89: 1555–1558, Bibcode:1984AJ.....89.1555S, doi:10.1086/113658.
- Schlegel, E. M.; et al. (October 1983), "Time-resolved spectrophotometry of the nova-like variable UX Ursa Majoris", Astrophysical Journal Supplement Series, 53: 397–412, Bibcode:1983ApJS...53..397S, doi:10.1086/190896.
- King, A. R.; et al. (May 1983), "Phase-dependent UV spectra of UX Ursae Majoris", Monthly Notices of the Royal Astronomical Society, 203 (3): 677–683, Bibcode:1983MNRAS.203..677K, doi:10.1093/mnras/203.3.677.
- Holm, A. V.; et al. (January 1982), "Ultraviolet spectrum variability of UX UMa", Astrophysical Journal, 252: L35–L37, Bibcode:1982ApJ...252L..35H, doi:10.1086/183714.
{{citation}}: CS1 maint: multiple names: authors list (link) - Frank, J.; et al. (May 1981), "Infrared and optical light curves of UX UMa and U Gem", Monthly Notices of the Royal Astronomical Society, 195: 505–516, Bibcode:1981MNRAS.195..505F, doi:10.1093/mnras/195.3.505.
- Panek, R. J.; Howell, S. B. (May 1980), "Time series photometry of UX UMa", Astronomical Journal, 85: 560–563, Bibcode:1980AJ.....85..560P, doi:10.1086/112712.
- Panek, R. J.; Zink, J. (September 1978), "Times of Minima of UX UMa", Information Bulletin on Variable Stars, 1468 (1): 1, Bibcode:1978IBVS.1468....1P.
- Quigley, R.; Africano, J. (August 1978), "Anomalous period change of UX Ursae Majoris in 1977", Publications of the Astronomical Society of the Pacific, 90: 445–450, Bibcode:1978PASP...90..445Q, doi:10.1086/130356, S2CID 118446990.
- Kukarkin, B. V. (July 1977), "Period changes of UX Ursae Majoris", Monthly Notices of the Royal Astronomical Society, 180: 5P–10P, Bibcode:1977MNRAS.180P...5K, doi:10.1093/mnras/180.1.5P.
- Mumford, G. S. (April 1976), "Recent Photoelectric Observations of UX Ursae Majoris", Information Bulletin on Variable Stars, 1128 (1): 1, Bibcode:1976IBVS.1128....1M.
- Africano, J.; Wilson, J. (February 1976), "On the possibility of apsidal motion in UX Ursae Majoris", Publications of the Astronomical Society of the Pacific, 88: 8–9, Bibcode:1976PASP...88....8A, doi:10.1086/129886, S2CID 121627020.
- Warner, B.; Nather, R. E. (1972), "Observations of rapid blue variables - XII. UX Ursae Majoris", Monthly Notices of the Royal Astronomical Society, 159 (4): 429, Bibcode:1972MNRAS.159..429W, doi:10.1093/mnras/159.4.429.
- Lukatskaya, F. I.; Pugach, A. F. (July 1970), "Autocorrelative Analysis of Light of DQ Her, UX UMa and RW Tri", Information Bulletin on Variable Stars, 457 (1): 1, Bibcode:1970IBVS..457....1L.
- Walker, M. F. (September 1968), "Observations of Primary Minimum of UX Ursae Maioris", Information Bulletin on Variable Stars, 298 (1): 1, Bibcode:1968IBVS..298....1W.
- Walker, Merle F.; Herbig, George H. (September 1954), "Photoelectric and Spectroscopic Observations of UX Ursae Majoris", Astrophysical Journal, 120: 278, Bibcode:1954ApJ...120..278W, doi:10.1086/145914.
- Johnson, H. L.; et al. (May 1954), "Photometric Investigation of the Eclipsing Binary UX Ursae Majoris", Astrophysical Journal Supplement, 1: 91, Bibcode:1954ApJS....1...91J, doi:10.1086/190004.
- Walker, Merle F. (August 1953), "Three-color Photoelectric Observations of UX Ursae Majoris", Publications of the Astronomical Society of the Pacific, 65 (385): 206, Bibcode:1953PASP...65..206W, doi:10.1086/126591, S2CID 122561650.