W Ursae Majoris

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W Ursae Majoris
Ursa Major constellation map.svg
Locator Dot.svg

The red dot shows the location of W Ursae Majoris in Ursa Major.
Observation data
Epoch J2000       Equinox J2000
Constellation Ursa Major
Right ascension 09h 43m 45.4705s [1]
Declination +55h 57m 09.0667s [1]
Apparent magnitude  (V)7.90 [2] (7.75–8.48)
Characteristics
Spectral type F8Vp + F8Vp [3]
U−B color index +0.08 [2]
B−V color index +0.66 [2]
Variable type W UMa
Astrometry
Radial velocity (Rv)−46 [4]  km/s
Proper motion (μ)RA: 17.150±0.049 [1]   mas/yr
Dec.: −29.226±0.050 [1]   mas/yr
Parallax (π)19.2775 ± 0.0334  mas [1]
Distance 169.2 ± 0.3  ly
(51.87 ± 0.09  pc)
Orbit [5]
Period (P)0.3336352(2) d
Semi-major axis (a)2.443 R☉ [6]
Inclination (i)88.4 ± 0.8°
Details [5]
W UMa A
Mass 1.139 ± 0.019  M☉
Radius 1.092 ± 0.016  R☉
Luminosity 1.557 ± 0.166  L☉
Temperature 6450 ± 100  K
Rotational velocity (v sin i)144.40 ± 6.52 [7]  km/s
W UMa B
Mass 0.551 ± 0.006  M☉
Radius 0.792 ± 0.015  R☉
Luminosity0.978 ± 0.071  L☉
Temperature 6170 ± 21  K
Other designations
BD+56 1400, HD  83950, SAO  27364, ADS 7494, CCDM 09438+5557, HIP  47727. [3]
Database references
SIMBAD The ADS 7494 pair
W UMa
ADS 7494B

W Ursae Majoris (W UMa) is the variable star designation for a binary star system in the northern constellation of Ursa Major. It has an apparent visual magnitude of about 7.9, [2] which is too faint to be seen with the naked eye. However, it can be viewed with a small telescope. [8] Parallax measurements place it at a distance of roughly 169  light years (52  parsecs) from Earth. [1]

A light curve for W Ursae Majoris, plotted from TESS data WUMaLightCurve.png
A light curve for W Ursae Majoris, plotted from TESS data

In 1903, the luminosity of this system was found to vary by the German astronomers Gustav Müller and Paul Kempf. It has since become the prototype and eponym for a class of variable stars called W Ursae Majoris variables. [10] This system consists of a pair of stars in a tight, circular orbit with a period of 0.3336 days, or eight hours and 26 seconds. [5] During every orbital cycle, each star eclipses the other, resulting in a decrease in magnitude. The maximum magnitude of the pair is 7.75 mag. During the eclipse of the primary, the net magnitude drops by 0.73 mag, while the eclipse of the secondary causes a magnitude decrease of 0.68 mag. [11]

The two stars in W Ursae Majoris are so close together that their outer envelopes are in direct contact, making them a contact binary system. As a result, they have the same stellar classification of F8Vp, which matches the spectrum of a main-sequence star that is generating energy through the nuclear fusion of hydrogen. However, the primary component has a larger mass and radius than the secondary, with 1.14 times the Sun's mass and 1.09 times the Sun's radius. The secondary has 0.55 solar masses and 0.79 solar radii. [5]

The orbital period of the system has changed since 1903, which may be the result of mass transfer or the braking effects of magnetic fields. Star spots have been observed on the surface of the stars and strong X-ray emissions have been detected, indicating a high level of magnetic activity that is common to W UMa variables. This magnetic activity may play a role in regulating the timing and magnitude of mass transfer occurs. [10]

W Ursae Majoris has a 12th magnitude companion star with the designation ADS 7494B, not to be confused with W UMa B, the secondary of the close eclipsing pair. They may be moving together through space. [12]

Related Research Articles

Mu Ursae Majoris, formally named Tania Australis, is a binary star in the constellation of Ursa Major. An apparent visual magnitude of +3.06 places it among the brighter members of the constellation. Parallax measurements give an estimated distance of roughly 230 light-years from the Sun, with a margin of error of 4%.

<span class="mw-page-title-main">44 Boötis</span> Triple star system in the constellation Boötes

44 Boötis or i Boötis is a triple star system in the constellation Boötes. It is approximately 41.6 light years from Earth.

<span class="mw-page-title-main">S Antliae</span> Star in the constellation Antlia

S Antliae is a W Ursae Majoris-type eclipsing binary star in Antlia.

<span class="mw-page-title-main">Y Sextantis</span> Variable star in the constellation Sextans

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.

<span class="mw-page-title-main">Epsilon Coronae Australis</span> Variable star in the constellation Corona Australis

Epsilon Coronae Australis, is a star system located in the constellation Corona Australis. Varying in brightness between apparent magnitudes of 4.74 to 5 over 14 hours, it is the brightest W Ursae Majoris variable in the night sky.

<span class="mw-page-title-main">65 Ursae Majoris</span> Star system in the constellation Ursa Major

65 Ursae Majoris, abbreviated as 65 UMa, is a star system in the constellation of Ursa Major. With a combined apparent magnitude of about 6.5, it is at the limit of human eyesight and is just barely visible to the naked eye in ideal conditions. It is about 760 light years away from Earth.

<span class="mw-page-title-main">SU Ursae Majoris</span> Variable star in the constellation Ursa Major

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.

<span class="mw-page-title-main">AB Andromedae</span> Binary star in the Andromeda constellation

AB Andromedae is a binary star in the constellation Andromeda. Paul Guthnick and Richard Prager discovered that the star is an eclipsing binary in 1927. Its maximum apparent visual magnitude is 9.49 but shows a variation in brightness down to a magnitude of 10.46 in a periodic cycle of roughly 8 hours. The observed variability is typical of W Ursae Majoris variable stars, so the two stars in this system form a contact binary.

<span class="mw-page-title-main">AE Phoenicis</span> Star in the constellation Phoenix

AE Phoenicis is a variable star in the constellation of Phoenix. An eclipsing binary, its apparent magnitude has a maximum of 7.56, dimming to 8.25 during primary eclipse and 8.19 during secondary eclipse. From parallax measurements by the Gaia spacecraft, the system is located at a distance of 168 light-years from Earth.

<span class="mw-page-title-main">V752 Centauri</span> Star in the constellation Centaurus

V752 Centauri is multiple star system and variable star in the constellation of Centaurus. An eclipsing binary, its apparent magnitude has a maximum of 9.10, dimming to 9.66 during primary eclipse and 9.61 during secondary eclipse. Its variability was discovered by Howard Bond in 1970. From parallax measurements by the Gaia spacecraft, the system is located at a distance of 410 light-years from Earth.

<span class="mw-page-title-main">TU Ursae Majoris</span>

TU Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major. It is classified as a Bailey-type 'ab' RR Lyrae variable with a period of 0.557648 days that ranges in brightness from apparent visual magnitude of 9.26 down to 10.24. The distance to this star is approximately 2,090 light years based on parallax measurements. It is located near the north galactic pole at a distance that indicates this is a member of the galactic halo.

<span class="mw-page-title-main">TX Ursae Majoris</span> Eclipsing binary star system in the constellation of Ursa Major

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.

<span class="mw-page-title-main">UX Ursae Majoris</span>

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.

<span class="mw-page-title-main">XY Ursae Majoris</span> Eclipsing binary star system in the constellation of Ursa Major

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.

<span class="mw-page-title-main">BZ Ursae Majoris</span> Dwarf Nova in the constellation Ursa Major

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.

<span class="mw-page-title-main">VZ Piscium</span> Variable star in the constellation Pisces

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.

<span class="mw-page-title-main">VV Ursae Majoris</span> Variable star system in the constellation Ursa Major

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.

<span class="mw-page-title-main">AW Ursae Majoris</span> Variable star in the constellation Ursa Major

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.

<span class="mw-page-title-main">DW Ursae Majoris</span> Variable star in the constellation Ursa Major

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. The brightness of this source ranges from an apparent visual magnitude of 13.6 down to magnitude 18, 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.

<span class="mw-page-title-main">2 Ursae Majoris</span> Am star in the constellation Ursa Major

2 Ursae Majoris is an Am star in the northern circumpolar constellation of Ursa Major, located 150 light-years from the Sun. It has the Bayer designation A Ursae Majoris; 2 Ursae Majoris is the Flamsteed designation. It is visible to the naked eye as a faint white star with an apparent visual magnitude of 5.5. Currently 150 light years away, it is moving closer to the Earth with a heliocentric radial velocity of −17 km/s.

References

  1. 1 2 3 4 5 6 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics . 616. A1. arXiv: 1804.09365 . Bibcode: 2018A&A...616A...1G . doi: 10.1051/0004-6361/201833051 . Gaia DR2 record for this source at VizieR.
  2. 1 2 3 4 Eggen, O. J. (September 1963), "Three-color photometry of the components in 228 wide double and multiple systems", Astronomical Journal, 68: 483–514, Bibcode:1963AJ.....68..483E, doi:10.1086/109000
  3. 1 2 "W UMa -- Spectroscopic binary", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-12
  4. ↑ Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W
  5. 1 2 3 4 Gazeas, K.; et al. (February 2021). "Physical parameters of close binary systems: VIII". Monthly Notices of the Royal Astronomical Society. 501 (2): 2897–2919. arXiv: 2101.10680 . Bibcode:2021MNRAS.501.2897G. doi:10.1093/mnras/staa3753.
  6. ↑ Gazeas, K.; Stȩpień, K. (November 2008), "Angular momentum and mass evolution of contact binaries", Monthly Notices of the Royal Astronomical Society, 390 (4): 1577–1586, arXiv: 0803.0212 , Bibcode:2008MNRAS.390.1577G, doi:10.1111/j.1365-2966.2008.13844.x, S2CID   14661232
  7. ↑ White, Russel J.; Gabor, Jared M.; Hillenbrand, Lynne A. (June 2007), "High-Dispersion Optical Spectra of Nearby Stars Younger Than the Sun", The Astronomical Journal, 133 (6): 2524–2536, arXiv: 0706.0542 , Bibcode:2007AJ....133.2524W, doi:10.1086/514336, S2CID   122854
  8. ↑ Sherrod, P. Clay; Koed, Thomas L. (2003), A Complete Manual of Amateur Astronomy: Tools and Techniques for Astronomical Observations, Astronomy Series, Courier Dover Publications, p. 9, ISBN   0-486-42820-6
  9. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  10. 1 2 Morgan, N.; Sauer, M.; Guinan, E. (1997), "New Light Curves and Period Study of the Contact Binary W Ursae Majoris", Information Bulletin on Variable Stars, 4517: 1, Bibcode:1997IBVS.4517....1M
  11. ↑ Malkov, O. Yu.; et al. (February 2006), "A catalogue of eclipsing variables" (PDF), Astronomy and Astrophysics, 446 (2): 785–789, Bibcode:2006A&A...446..785M, doi: 10.1051/0004-6361:20053137
  12. ↑ Rucinski, S. M.; Lu, W.-X.; Shi, J. (September 1993), "Spectral-line broadening functions of W UMa-type binaries. III - W UMa", Astronomical Journal, 106 (3): 1174–1180, Bibcode:1993AJ....106.1174R, doi: 10.1086/116716
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