| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 01h 04m 35.53730s[2] |
| Declination | +41° 17′ 57.78369″[2] |
| Apparent magnitude (V) | 10.2 to 15.1[3] |
| Characteristics | |
| Spectral type | pec(UG)[3] |
| B−Vcolor index | -0.4556[4] |
| Variable type | UGZ[3] |
| Astrometry | |
| Radial velocity (Rv) | -12[5] km/s |
| Proper motion (μ) | RA: 1.217 ± 2.221[6]mas/yr Dec.: -22.225 ± 0.699[6]mas/yr |
| Parallax (π) | 5.0276±0.0507 mas[2] |
| Distance | 649 ± 7 ly (199 ± 2 pc) |
| Orbit | |
| Period (P) | 5.075[7] hours |
| Details | |
| White dwarf | |
| Mass | 0.8[8] M☉ |
| Surface gravity (log g) | 8.2[8] cgs |
| Temperature | 40,000 - 45,000[8] K |
| Rotational velocity (v sin i) | 200[8] km/s |
| Donor star | |
| Surface gravity (log g) | 4.5[9] cgs |
| Temperature | 3,500[9] K |
| Metallicity | +0.07[9] |
| Other designations | |
| 2MASS J01043553+4117577,TYC 2807-1623-1 | |
| Database references | |
| SIMBAD | data |
RX Andromedae is avariable star in the constellation ofAndromeda. Although it is classified as adwarf nova of theZ Camelopardalis (UGZ) type, it has shown low-luminosity periods typical ofVY Sculptoris stars.[10] However, for most of the time it varies from anapparent visual magnitude of 15.1 at minimum brightness to a magnitude of 10.2 at maximum brightness, with a period of approximately 13 days.[3]
RX Andromedae is acataclysmic variable system, where awhite dwarf with a mass of 0.8M☉ and an M2main sequence star[9] are rotating around their center of mass. The main sequence star is overfilling itsRoche lobe, so the white dwarf is stripping away matter from the companion star and accreting it through anaccretion disk.[10]
In 1904, English amateur astronomerArthur Stanley Williams discovered RX Amdromedae, and he observed it visually (with a 6.5 inchreflector) from late 1904 until early 1905. He initially believed it to be aCepheid variable, but after examining images of the star onphotographic plates dating back to late 1899, he concluded it was aU Geminorum variable. He published itsvariable star designation in 1906.[11][12]
Like the Z Camelopardalis variables, RX Andromedae shows some periods of roughly constant luminosity and others where its brightness oscillates between a magnitude of 10.2 at its maximum and one of 15.1 at its minimum. However, between 1996 and 1997 it was stuck at its minimum brightness like cataclysmic variables of VY Sculptoris type, before going back to the usual behaviour. This places RX Andromedae in a transitional state between those two kind of objects.[10] The white dwarf and its accretion disk seems to be entirely responsible for this variability, and it's driven by changes in the accretion rate of the white dwarf.[8]
RX Andromedae has been extensively studied in optical and ultraviolet. It's also one of the few dwarf nova systems that have been detected at radio wavelengths.[13]
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