Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ursa Major |
Right ascension | 10h 33m 52.875s[2] |
Declination | +58° 46′ 54.72″[2] |
Apparent magnitude (V) | 13.6 to 18.0[3] |
Characteristics | |
Spectral type | M7±2.0[4] |
Variable type | Algol variable[5] |
Astrometry | |
Proper motion (μ) | RA: 0.974 mas/yr[2] Dec.: 1.396 mas/yr[2] |
Parallax (π) | 1.6958 ± 0.0196 mas[2] |
Distance | 1,920 ± 20 ly (590 ± 7 pc) |
Orbit | |
Period (P) | 3.2785566 h[3] |
Semi-major axis (a) | 1.14±0.06 R☉[4] |
Inclination (i) | 82±4[4]° |
Details | |
White dwarf | |
Mass | 0.77±0.07[4] M☉ |
Radius | 0.012±0.001[4] R☉ |
Surface gravity (log g) | 8[4] (assumed) cgs |
Temperature | 50,000±1,000[4] K |
Red dwarf | |
Mass | 0.25±0.05[6] M☉ |
Radius | 0.34±0.04[4] R☉ |
Other designations | |
Database references | |
SIMBAD | data |
DW Ursae Majoris is an eclipsing binary star system in the northern circumpolar constellation of Ursa Major, abbreviated DW UMa. It is a cataclysmic variable of the SX Sextanis type, consisting of a compact white dwarf that is accreting matter from an orbiting companion star.[8] The brightness of this source ranges from an apparent visual magnitude of 13.6 down to magnitude 18,[5] which is too faint to be viewed with the naked eye. The distance to this system is approximately 1,920 light years based on parallax measurements.[2]
In 1982, R. F. Green and associates identified this star as a cataclysmic variable candidate with the Palomar–Green survey designation PG 1030+590.[9] A. W. Shafter and F. V. Hessman in 1984 found this to be a close eclipsing binary system with a period of 3.27 hours.[10] This is a nova-like binary where mass is being transferred from a late-type star to a white dwarf companion. This material is first accumulated in an accretion disk orbiting the white dwarf. Typically, the light curve for an eclipsing binary of this type should display a hump-like feature from where the stream of material interacts with the disk. However, during early observations, no such feature was observed before the eclipse.[11]
The behavior of the emission lines in the spectrum of this star were found to resemble those of other SW Sextantis variables.[12] In 2000, the system was observed with the Hubble Space Telescope and was found to be in a low state about three magnitudes fainter, unlike previous observations where it had been in a high state. Comparison of the ultraviolet spectrum in the two states suggested that the accretion disk is self-eclipsing and it can obscure the view of the white dwarf.[8] The light output of the system undergoes a 13.6 year cycle of variation, probably because of precession of the accretion disk. Both positive and negative superhumps are observed that vary over time in a complex fashion. Mass is being transferred from the donor star at a rate of about 10−8 M☉·yr−1.[6]
MAST
was invoked but never defined (see the help page).GaiaEDR3
was invoked but never defined (see the help page).vsx
was invoked but never defined (see the help page).Araujo-Betancor_et_al_2003
was invoked but never defined (see the help page).Samus_et_al_2017
was invoked but never defined (see the help page).Boyd_et_al_2017
was invoked but never defined (see the help page).SIMBAD
was invoked but never defined (see the help page).Knigge_et_al_2000
was invoked but never defined (see the help page).Green_et_al_1982
was invoked but never defined (see the help page).Shafter_Hessman_1984
was invoked but never defined (see the help page).Szkody_1987
was invoked but never defined (see the help page).Thorstensen_et_al_1991
was invoked but never defined (see the help page).