A visual band light curve for BM Andromedae, plotted from data published by Grinin et al. (1995) [1] | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Andromeda |
Right ascension | 23h 37m 38.49052s [2] |
Declination | +48° 24′ 11.7624″ [2] |
Apparent magnitude (V) | 11.63 – 14.02 [3] |
Characteristics | |
Spectral type | F8ea-K5Vea [3] |
Apparent magnitude (B) | 12.40 [4] |
Apparent magnitude (V) | 12.40 [5] |
Apparent magnitude (G) | 12.76 [2] |
Apparent magnitude (J) | 10.524 [6] |
Apparent magnitude (H) | 9.523 [6] |
Apparent magnitude (K) | 8.810 [6] |
Variable type | T Tauri star [1] |
Astrometry | |
Radial velocity (Rv) | −12.37±3.96 [2] km/s |
Proper motion (μ) | RA: −5.249 [2] mas/yr Dec.: +8.452 [2] mas/yr |
Parallax (π) | 1.2732 ± 0.6439 mas [2] |
Distance | approx. 3,000 ly (approx. 800 pc) |
Details | |
Luminosity (bolometric) | 5.5 [7] L☉ |
Other designations | |
2MASS J23373847+4824119, GSC 03642-00171 | |
Database references | |
SIMBAD | data |
BM Andromedae (BM And) is a T Tauri star in the constellation Andromeda. Its apparent visual magnitude has irregular variations between a maximum of 11.63 and a minimum of 14.02. [3]
The exact spectral class of the star is not yet known. Different estimations gives a range F8-K5Vea, [3] meaning that there is agreement in identifying it as a main sequence star more luminous and with stronger emission lines than the usual, a typical classification for young stars that are near the main sequence phase. The star is still accreting, and about 0.23 L☉ of 5.5 L☉ of its total luminosity is powered by accretion. [7]
The color indexes vary with the star's brightness, but the spectral class of BM Andromedae does not change with the decrease of luminosity. Strong H-alpha lines in the spectra are a sign of a gaseous envelope, while an infrared excess indicates the existence of an extended dust envelope. [1]
BM Andromedae is a young stellar object with a circumstellar cloud around it, one stage of the evolution from protostars to the main sequence phase. The cloud is made of a gaseous envelope and an extended dust envelope. The latter can reach a distance of 1 AU from the star and is strongly flattened and observed edge-on. [1] The measurements in 2005-2006 have showed a relatively compact, 0.25 AU disk. [7]
It was also found that a correlation exists between the local interstellar magnetic field and the polarization of light emitted by BM Andromedae. Thus, the magnetic field could have played a role in the formation of the system. [1]
In 1949 Balfour Whitney announced that BM Andromedae (at the time, an unnamed star) is a variable star, based on 400 photographic plates taken from 1942 through 1949. He noted that it varied rapidly and irregularly, sometimes varying by 1 magnitude over the course of a single day. [8]
The envelope blocks a fraction of the light emitted by BM Andromedae, but it's not uniform so this fraction is variable in time. This explains both the brightness variability and the one of color indexes. It was also found that the dust envelope polarizes the light emitted by BM Andromedae; the more light is blocked, the stronger is the polarization. [1] The color of star is dependent on brightness; it becomes redder when fainter. [9]
U Antliae is a variable star in the constellation Antlia. It is a carbon star surrounded by two thin shells of dust.
Phi Persei is a class B2Vep fourth-magnitude star in the constellation Perseus, location about 720 light-years from Earth.
HD 37974 a variable B[e] hypergiant in the Large Magellanic Cloud. It is surrounded by an unexpected dust disk.
HD 224801, also known as CG Andromedae, is an Alpha² Canum Venaticorum variable star in the constellation Andromeda. Located approximately 188 parsecs (610 ly) away, the star varies between apparent magnitudes 6.32 and 6.42 over a period of approximately 3.74 days.
WR 148 is a spectroscopic binary in the constellation Cygnus. The primary star is a Wolf–Rayet star and one of the most luminous stars known. The secondary has been suspected of being a stellar-mass black hole but may be a class O main sequence star.
IK Tauri or NML Tauri is a Mira variable star located about 280 parsecs (910 ly) from the Sun in the zodiac constellation of Taurus.
WR 9 is a spectroscopic binary in the constellation Puppis consisting of a Wolf-Rayet star and a class O star. It is around 12,000 light years away.
QV Andromedae is an Alpha2 Canum Venaticorum variable in the constellation Andromeda. Its maximum apparent visual magnitude is 6.6, so it can be seen by the naked eye under very favourable conditions. The brightness varies slightly following a periodic cycle of approximately 5.23 days.
AD Andromedae is an eclipsing binary in the constellation Andromeda. Its maximum apparent visual magnitude is 11.2, but it shows a decrease of 0.62 magnitudes during the main eclipse and 0.58 during the secondary one. It is classified as a Beta Lyrae variable star with a period of almost one day.
AR Andromedae is a dwarf nova of the SS Cygni type in the constellation Andromeda. Its typical apparent visual magnitude is 17.6, but increases up to 11.0 magnitude during outbursts. The outbursts occur approximately every 23 days.
CC Andromedae is a variable star in the constellation Andromeda. It is a pulsating star of the Delta Scuti type, with an apparent visual magnitude that varies between 9.19 and 9.46 with a periodicity of 3 hours.
EU Andromedae is a carbon star in the constellation Andromeda. Its apparent visual magnitude varies in an irregular manner between 10.7 and 11.8.
FF Andromedae is a spectroscopic binary in the constellation Andromeda. It has a typical apparent visual magnitude of 10.4, but undergoes flare events that can increase its brightness by about a magnitude.
GR Andromedae is a variable star in the constellation Andromeda. Its apparent visual magnitude varies between 6.87 and 6.95 in a cycle of 518.2 days. It is classified as an α2 Canum Venaticorum variable.
KX Andromedae is a spectroscopic binary star in the constellation Andromeda. Its apparent visual magnitude varies between 6.88 and 7.28.
LP Andromedae is a carbon star in the constellation Andromeda. It is also a Mira variable whose mean apparent visual magnitude is 15.12 and has pulsations with an amplitude of 1.50 magnitudes and a period of 614 days.
QX Andromedae is an eclipsing binary in the constellation Andromeda. It varies from a maximum apparent visual magnitude of 11.28 to a minimum of 11.50. Since it is impossible to specify the onset time of the eclipses, it is classified as a W Ursae Majoris variable star. It is also observed as an X-ray source and is a member of the open cluster NGC 752.
DH Tauri, also known as DH Tau, is a type M star, located 140 parsecs away. It forms a binary system with DI Tauri 15″ away, and has a substellar companion, either a brown dwarf or massive exoplanet.
WR 133 is a visually moderately bright Wolf-Rayet star. It is a spectroscopic binary system containing a Wolf-Rayet primary and a class O supergiant secondary. It is in the constellation of Cygnus, lying in the sky at the centre of the triangle formed by β and γ Cygni, near η Cygni. It is the brightest member of the sparse open cluster NGC 6871.
R Fornacis is a Mira variable and carbon star located in the constellation Fornax. It is around 1,800 light years away based on parallax measurements.