EF Eridani
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| Observation data Epoch J2000.0 Equinox J2000.0 |
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| Constellation | Eridanus |
| Right ascension | 03h 14m 13.03s[1] |
| Declination | −22° 35′ 41.4″[1] |
| Apparent magnitude (V) | 14.5–17.3[2] |
| Characteristics | |
| Variable type | E+XM[2] |
| Astrometry | |
| Radial velocity (Rv) | 70[1] km/s |
| Distance | 300[3] ly |
| Other designations | |
| Database references | |
| SIMBAD | data |
EF Eridani (abbreviated EF Eri, sometimes incorrectly referred to as EF Eridanus) is a variable star of the type known as polars, AM Herculis stars, or magnetic cataclysmic variable stars. Historically it has varied between apparent magnitudes 14.5 and 17.3, although since 1995 it has generally remained at the lower limit. The star system consists of a white dwarf with a substellar massed former star in orbit.
EF Eridani B
The substellar mass in orbit around the white dwarf is a star which lost all of its gas to the white dwarf, except what remains, a 0.05 solar mass (M☉) ball, which is too small to continue fusion, and does not have the composition of a super-planet, brown dwarf, or white dwarf. There is no category for such a stellar remnant.[4]
It is theorized that 500 million years ago, the white dwarf started to cannibalize its partner, when they were separated by 7 million km. As it lost mass, the regular star spiralled inward, until now they are separated by a mere 700,000 km.[4]
Another former star orbits the pulsar PSR J1719-1438.[5]
See also
- AM Herculis
- Cataclysmic variable star
- Polar (cataclysmic variable)
- Variable stars
- Stellar remnants
- PSR J1719-1438, a star system with a planetary-mass former star in orbit around a compact star
- PSR J1719-1438 b, a planetary-mass former star that was eroded by its binary star partner
References
- ↑ 1.0 1.1 1.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Mystery Object Neither Star Nor Brown Dwarf
- ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
External links
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