DW Ursae Majoris

DW Ursae Majoris

A light curve for DW Ursae Majoris, plotted from TESS data[1]
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]
Distance1,920 ± 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
Mass0.77±0.07[4] M☉
Radius0.012±0.001[4] R☉
Surface gravity (log g)8[4] (assumed) cgs
Temperature50,000±1,000[4] K
Red dwarf
Mass0.25±0.05[6] M☉
Radius0.34±0.04[4] R☉
Other designations
PG 1030+590, DW UMa, GSC 03822-00464, 2MASS J10335283+5846547[7]
Database references
SIMBADdata

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]

  1. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference vsx was invoked but never defined (see the help page).
  4. ^ a b c d e f g h Cite error: The named reference Araujo-Betancor_et_al_2003 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Boyd_et_al_2017 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Knigge_et_al_2000 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Green_et_al_1982 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Shafter_Hessman_1984 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Szkody_1987 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Thorstensen_et_al_1991 was invoked but never defined (see the help page).