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]
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]