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]
Y Sextantis, abbreviated as Y Sex, is a variable star system in the equatorial constellation of Sextans. The system is invisible to the naked eye with a mean apparent visual magnitude of 9.88. It is located roughly at 1,300 light years from the Sun based on parallax.
AN Ursae Majoris is a binary star system in the northern circumpolar constellation of Ursa Major. It is a variable star, with AN Ursae Majoris being the variable star designation, and ranges in brightness from 14.90 down to 20.2. Even at its peak brightness though, the system is much too faint to be visible to the naked eye. Based on parallax measurements, the system is located roughly 1,050 light years away from the Sun.
EK Trianguli Australis is a star in the constellation Triangulum Australe. It is a dwarf nova of the SU Ursae Majoris type that officially classified as such in 1980, after the characteristic eruptions of a short eruption and a supereruption were observed in May 1978 and June 1979 respectively. These systems are characterised by frequent eruptions and less frequent supereruptions. The former are smooth, while the latter exhibit short "superhumps" of heightened activity. The distance of the system has been assumed at 180 parsecs from the Solar System, for the donor star. Spectroscopic analysis and calculation gave an estimate of 125 parsecs.
SW Sextantis variable stars are a kind of cataclysmic variable star; they are double-star systems in which there is mass transfer from a red dwarf to a white dwarf forming a stable accretion disc around the latter. Unlike other non-magnetic cataclysmic variables, the emission lines from hydrogen and helium are not doubled, except briefly near phase 0.5.
SU Ursae Majoris, or SU UMa, is a close binary star in the northern circumpolar constellation of Ursa Major. It is a periodic cataclysmic variable that varies in magnitude from a peak of 10.8 down to a base of 14.96. The distance to this system, as determined from its annual parallax shift of 4.53 mas, is 719 light-years. It is moving further from the Earth with a heliocentric radial velocity of +27 km/s.
PX Andromedae is an eclipsing cataclysmic variable star in the constellation Andromeda. It has been classified as a SW Sextantis variable, and its apparent visual magnitude varies between 14.04 and 17.
V1315 Aquilae is a cataclysmic variable star in the north of the equatorial constellation of Aquila. It is in the sub-set of nova-like (NL) variables, specifically a SW Sextantis star. These were characterized as having non-magnetic white dwarfs – thus that do not undergo dwarf-nova bright luminations ("eruptions"). There is countering evidence for some magnetism. Being a SW Sextantis star, V1315 Aquilae has a high rate of mass transfer, so it is in steady-state accretion and in a constant state of outburst. It emits most of its light in the visible range, and this comes from the accretion disk. The eclipse depth is 1.8 mag. No description of the donor star is made.
TX Ursae Majoris is an eclipsing binary star system in the northern circumpolar constellation of Ursa Major. With a combined apparent visual magnitude of 6.97, the system is too faint to be readily viewed with the naked eye. The pair orbit each other with a period of 3.063 days in a circular orbit, with their orbital plane aligned close to the line of sight from the Earth. During the primary eclipse, the net brightness decreases by 1.74 magnitudes, while the secondary eclipse results in a drop of just 0.07 magnitude. TX UMa is located at a distance of approximately 780 light years from the Sun based on parallax measurements, but is drifting closer with a mean radial velocity of −13 km/s.
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. Since its discovery in 1933, this system has been the subject of numerous studies attempting to determine its properties. The combined apparent visual magnitude of UX UMa ranges from 12.57 down to 14.15. The system is located at a distance of approximately 952 light years from the Sun based on parallax, and is drifting further away with a radial velocity of 112 km/s.
XY Ursae Majoris is a short period binary star system in the northern circumpolar constellation of Ursa Major. It is an eclipsing binary with a baseline apparent visual magnitude of 9.50. The system is located at a distance of 221.5 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −10 km/s. It has a relatively high proper motion, traversing the celestial sphere at the angular rate of 0.191″·yr−1.
BZ Ursae Majoris is a dwarf nova star system in the northern circumpolar constellation of Ursa Major. It consists of a white dwarf primary in a close orbit with a red dwarf. The latter star is donating mass, which is accumulating in an accretion disk orbiting the white dwarf. The system is located at a distance of approximately 505 light years from the Sun based on parallax measurements.
RZ Leonis Minoris is a cataclysmic variable star system in the northern constellation of Leo Minor. It undergoes frequent outbursts that vary in brightness from an apparent visual magnitude of 14.4 down to 16.8. Based on parallax measurements, this system is located at a distance of approximately 2,160 light years from the Sun.
VZ Piscium is a binary star system in the equatorial constellation of Pisces. it is located at a distance of 178 light years from the Sun based on parallax measurements, and has an apparent visual magnitude of about 10.3. This is an eclipsing binary system that undergoes shallow eclipses; the brightness decreases to magnitude 10.45 during the primary eclipse, then to magnitude 10.43 with the secondary eclipse, although as a contact binary the brightness varies continuously with no period of constant maximum brightness. The system is drifting closer with a radial velocity of approximately −4 km/s, and has a net heliocentric velocity of 144.1 km/s.
AH Virginis is a contact binary star system in the equatorial constellation of Virgo, abbreviated AH Vir. It is a variable star with a brightness that peaks at an apparent visual magnitude of 9.18, making it too faint to be viewed with the naked eye. The distance to this system is approximately 338 light years based on parallax measurements, and it is drifting further away with a mean radial velocity of 7 km/s. O. J. Eggen in 1969 included this system as a probable member of the Wolf 630 group of co-moving stars.
SW Ursae Majoris is a cataclysmic binary star system in the northern circumpolar constellation of Ursa Major, abbreviated SW UMa. During quiescence it has an apparent visual magnitude of 16.5–17, which is too faint to be visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 526 light years from the Sun.
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, 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.
AW Ursae Majoris is a binary star system in the northern circumpolar constellation of Ursa Major, abbreviated AW UMa. It is an A-type W Ursae Majoris variable with an apparent visual magnitude of 6.83, which is near the lower limit of visibility to the naked eye. This is an eclipsing binary with the brightness dropping to magnitude 7.13 during the primary eclipse and to 7.08 with the secondary eclipse. Parallax measurements give a distance estimate of 221 light years from the Sun. It is drifting closer to the Sun with a radial velocity of approximately −17 km/s. The system has a high proper motion, traversing the celestial sphere at the rate of 0.216 arc second per annum.
BE Ursae Majoris is a binary star system in the northern circumpolar constellation of Ursa Major, abbreviated BE UMa. The two components are an unusual M-class dwarf star and a subdwarf O star, borderline white dwarf. It is classified as a detached Algol variable and ranges in brightness from an apparent visual magnitude of 14.8 down to 17.8. This is too faint to be visible to the naked eye. The distance to this system is approximately 4,600 light years based on parallax measurements.
ER Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major, abbreviated ER UMa. It is a prototype system for a subclass of SU Ursae Majoris dwarf novae. The system ranges in brightness from a peak apparent visual magnitude of 12.4 down to 15.2, which is too faint to be visible to the naked eye. The distance to this system, based on parallax measurements, is approximately 1,163 light years.
CR Boötis is an interacting binary system in the northern constellation of Boötes, abbreviated CR Boo. It is one of the best-known AM Canum Venaticorum stars. The system varies widely in brightness, ranging in apparent visual magnitude from 13.6 down to 17.5. The distance to this system is approximately 1,150 light years from the Sun, based on parallax measurements.