EX Hydrae
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Hydra |
Right ascension | 12h 52m 24.20s |
Declination | -29° 14′ 56.0″ |
Apparent magnitude (V) | 9.6 to 14 (variable) |
Characteristics | |
Spectral type | white dwarf + M4/M5: |
Variable type | DQ Herculis |
Astrometry | |
Radial velocity (Rv) | −54[3] km/s |
Details | |
Mass | 0.55 ± 0.15[4] M☉ |
Rotation | 67 minutes |
Mass | 0.085 ± 0.015[4] M☉ |
Other designations | |
1RXS J125224.7-291451, 2E 2876, RX J1252.4-2914, AAVSO 1247-28 | |
Database references | |
SIMBAD | data |
EX Hydrae is a variable star classified as an eclipsing intermediate polar-type cataclysmic variable, specifically of the DQ Herculis type.[3] The system varies in apparent magnitude from 9.6 to 14.[5] The system consists of a white dwarf primary and an M-type secondary, of masses of 0.4–0.7 M☉ and 0.07–0.10 M☉ respectively.[4] The orbital period is 98.25696 minutes (0.068233846 days).[6] The system is 65±11 parsecs distant, making EX Hya one of the closest cataclysmic variable stars.[7] The cataclysmic outbursts appear to be caused by accretion of material from the M-star to the white dwarf.[6]
EX Hydrae also possess a 67-minute oscillation, believed to be caused by the spin period of the white dwarf component.[6] EX Hydrae's outbursts are unpredictable.
References
- ^ Warner, B.; McGraw, J. T. (August 1981). "EX Hyd : modulated mass transfer of intermediate polar?". Monthly Notices of the Royal Astronomical Society. 196: 59P–63P. Bibcode:1981MNRAS.196P..59W. doi:10.1093/mnras/196.1.59P.
- ^ Reinsch, K.; Beuermann, K. (December 1990). "Photometric observations of the intermediate polar EX Hydrae in outburst". Astronomy and Astrophysics. 240: 360–364. Bibcode:1990A&A...240..360R.
- ^ a b "V* EX Hya". SIMBAD. Centre de données astronomiques de Strasbourg.
- ^ a b c Beuermann, K.; Harrison, Th. E.; McArthur, B. E.; Benedict, G. F.; Gänsicke, B. T. (2003). "A precise HST parallax of the cataclysmic variable EX Hydrae, its system parameters, and accretion rate". Astronomy & Astrophysics. 412 (3): 821–827. arXiv:astro-ph/0309530. Bibcode:2003A&A...412..821B. doi:10.1051/0004-6361:20031498. S2CID 3167825.
- ^ locator chart at AAVSO
- ^ a b c "AAVSO". Archived from the original on 2010-06-15. Retrieved 2009-04-24.
- ^ Eisenbart, S.; Beuermann, K.; Reinsch, K.; Gänsicke, B. T. (2002). "Multi-wavelength spectrophotometry of EX Hydrae". Astronomy & Astrophysics. 382 (3): 984–998. arXiv:astro-ph/0111459. Bibcode:2002A&A...382..984E. doi:10.1051/0004-6361:20011655. S2CID 12934377.
External links
- AAVSO Variable Star of the Month. EX Hydrae: April 2009 Archived 2010-06-15 at the Wayback Machine