A light curve for BE Ursae Majoris, adapted from Shimanskii et al. (2008).[1] The inset plot shows the time around the eclipse with an expanded scale.
Observation data Epoch J2000 Equinox J2000
Constellation
Ursa Major
Right ascension
11h 57m 44.828s[2]
Declination
+48° 56′ 18.31″[2]
Apparent magnitude (V)
14.8 to 17.8[3]
Characteristics
Spectral type
DO + M1e–M5e[4]
Variable type
Detached Algol[3]
Astrometry
Radial velocity (Rv)
−67±2[5] km/s
Proper motion (μ)
RA: 10.706 mas/yr[2] Dec.: −12.783 mas/yr[2]
Parallax (π)
0.7079 ± 0.0257 mas[2]
Distance
4,600 ± 200 ly (1,410 ± 50 pc)
Details
Subdwarf O star
Mass
0.59±0.07[1]M☉
Radius
0.078±0.004[5]R☉
Surface gravity (log g)
6.5±0.1[5] cgs
Temperature
105,000±5,000[5] K
M class dwarf
Mass
0.25±0.08[1]M☉
Radius
0.72±0.05[5]R☉
Temperature
4,750±150[1] K
Other designations
PG 1155+492, SVS 1424, BE UMa, 2MASS J11574483+4856184[6]
Database references
SIMBAD
data
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.[3] 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.[2]
The variability of SVS 1424 was announced in 1964 by N. E. Kurochkin from Sternberg,[7] and was found to have a period of 2.291 days while ranging in brightness from magnitude 14.1 down to 15.6.[8] After being assigned the variable star designation BE UMa, it was discovered to be a source of hot ultraviolet emission with a helium-rich spectrum by D. H. Ferguson and associates in 1981.[9] B. Margon and associates found variability of spectral features on a time scale as low as a few hours. They interpreted this as a detached binary system consisting of a compact, high temperature white dwarf and a cool red dwarf star. The outer layers of the cooler star are being ionized by radiation from the hotter component,[10] and the changing orientation of this heated region over the course of an orbit is creating a sinusoidal variability of about 1.5 magnitudes.[11]
In 1982, a deep eclipse was discovered in the light curve by H. Ando and associates. This put a strong limit on the possible models for the system, which indicated that the compact component is a hot O-type subdwarf.[12] D. Crampton and associates in 1983 found that the temperature and radius of the cool component suggested that it is an evolved subgiant star. At present, no mass transfer is taking place, but the system appears to be evolving into a cataclysmic variable as the subdwarf cools to become a normal white dwarf.[11]
In 1995, J. Liebert and associates discovered that the system is surrounded by a planetary nebula with a diameter of 3′, which was likely shed when the present day subdwarf was leaving the asymptotic giant branch stage. The two components would have shared a common envelope as little as 10,000 years ago. As a result, rather than being a subgiant, the cool component has not yet reached the thermal equilibrium of a late dwarf star.[13] The pair have a circular orbit with a period of 2.2911658 days and a separation of 7.5±0.5 R☉. The orbital plane is inclined at an angle of 84°±1° to the line of sight from the Earth.[5]
^ abcdCite error: The named reference Shimanskii_et_al_2008 was invoked but never defined (see the help page).
^ abcdeCite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
^ abcCite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
^Cite error: The named reference Ferguson_et_al_1987 was invoked but never defined (see the help page).
^ abcdefCite error: The named reference Ferguson_et_al_1999 was invoked but never defined (see the help page).
^Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
^Cite error: The named reference Kurochkin_1964 was invoked but never defined (see the help page).
^Cite error: The named reference Kurochkin_1971 was invoked but never defined (see the help page).
^Cite error: The named reference Ferguson_et_al_1981 was invoked but never defined (see the help page).
^Cite error: The named reference Margon_et_al_1981 was invoked but never defined (see the help page).
^ abCite error: The named reference Crampton_et_al_1983 was invoked but never defined (see the help page).
^Cite error: The named reference Ando_et_al_1982 was invoked but never defined (see the help page).
^Cite error: The named reference Liebert_et_al_1995 was invoked but never defined (see the help page).
BEUrsaeMajoris is a binary star system in the northern circumpolar constellation of Ursa Major, abbreviated BE UMa. The two components are an unusual...
constellation of Ursa Major. It has the Bayer designation ζ UrsaeMajoris (Latinised as Zeta UrsaeMajoris). It forms a well-known naked eye double star with the...
"Little Dipper". Two of its stars, named Dubhe and Merak (α UrsaeMajoris and β UrsaeMajoris), can be used as the navigational pointer towards the place of...
Dubhe /ˈdʌbiː/, also called Alpha UrsaeMajoris, Latinised from α UrsaeMajoris, is, despite being designated "α" (alpha), the second-brightest object...
47 UrsaeMajoris (abbreviated 47 UMa), formally named Chalawan /ˈtʃɑːləwən/, is a yellow dwarf star approximately 45.3 light-years from Earth in the constellation...
Megrez /ˈmiːɡrɛz/, also called Delta UrsaeMajoris (δ UrsaeMajoris, abbreviated Delta UMa, δ UMa), is a star in the northern constellation of Ursa Major...
47 UrsaeMajoris b (abbreviated 47 UMa b), formally named Taphao Thong /təˌpaʊ ˈtɒŋ/, is a gas planet and an extrasolar planet approximately 46 light-years...
Alkaid /ælˈkeɪd/, also called Eta UrsaeMajoris (Latinised from η UrsaeMajoris, abbreviated Eta UMa, η UMa), is a star in the constellation of Ursa Major...
This is the list of notable stars in the constellation Ursa Major, sorted by decreasing brightness. List of stars by constellation Final Results of NameExoWorlds...
Xi UrsaeMajoris is a quintuple star system 28.5 light-years (8.7 parsecs) away in the constellation of Ursa Major. It has the traditional name Alula...
called Epsilon UrsaeMajoris, is a star in the northern constellation of Ursa Major. The designation is Latinised from ε UrsaeMajoris and abbreviated...
Iota UrsaeMajoris (ι UrsaeMajoris, abbreviated Iota UMa, ι UMa), also named Talitha /ˈtælɪθə/, is a star system in the northern circumpolar constellation...
W UrsaeMajoris (W UMa) is the variable star designation for a binary star system in the northern constellation of Ursa Major. It has an apparent visual...
47 UrsaeMajoris c (abbreviated 47 UMa c), formally named Taphao Kaew (/təˌpaʊ ˈɡaʊ/ tə-POW GOW; Thai: ตะเภาแก้ว [tāpʰāwkɛ̂ːw]) is an extrasolar planet...
Mu UrsaeMajoris (μ UrsaeMajoris, abbreviated Mu UMa, μ UMa), formally named Tania Australis /ˈteɪniə ɔːˈstreɪlɪs/, is a binary star in the constellation...
exoplanet designated Omicron UrsaeMajoris Ab was found to be orbiting the primary. ο UrsaeMajoris (Latinised to Omicron UrsaeMajoris) is the star's Bayer designation...
Phecda /ˈfɛkdə/, also called Gamma UrsaeMajoris (γ UrsaeMajoris, abbreviated Gamma UMa, γ UMa), is a star in the constellation of Ursa Major. Since 1943...
4 UrsaeMajoris (sometimes abbreviated 4 UMa) is the Flamsteed designation of a star in the northern circumpolar constellation of Ursa Major. It also...
Nu UrsaeMajoris (ν UrsaeMajoris, abbreviated Nu UMa, ν UMa), formally named Alula Borealis /əˈluːlə bɒriˈælɪs/, is a double star in the northern circumpolar...
"super-outbursts," in addition to normal outbursts. Varieties of SU UrsaeMajoris star include ER UrsaeMajoris stars and WZ Sagittae stars (UGWZ). Z Camelopardalis...
Lambda UrsaeMajoris (λ UrsaeMajoris, abbreviated Lambda UMa, λ UMa), formally named Tania Borealis /ˈteɪniə ˌbɒriˈælɪs/, is a star in the northern circumpolar...
Theta UrsaeMajoris (Theta UMa, θ UrsaeMajoris, θ UMa) is a suspected spectroscopic binary star system in the northern circumpolar constellation of Ursa...
61 UrsaeMajoris, abbreviated 61 UMa, is a single star in the northern circumpolar constellation of Ursa Major. It has a yellow-orange hue and is dimly...
Sigma2 UrsaeMajoris (σ2 UrsaeMajoris, σ2 UMa) is a binary star in the constellation of Ursa Major. Parallax measurements made by the Hipparcos spacecraft...
84 UrsaeMajoris, also known as HD 120198, is a star about 300 light years from the Earth, in the constellation Ursa Major. It is a 5th magnitude star...
Chi UrsaeMajoris or χ UrsaeMajoris, formally named Taiyangshou /ˌtaɪˌjæŋˈʃoʊ/, is a single star in the northern circumpolar constellation of Ursa Major...
Global Information