Abell 35, also known as Sh 2-313, is a nebula located in the constellation of Hydra, at a distance of 400 light years. The nebula is characterised by its unusual appearance, which features a central bow shock surrounded by symmetric emission.[2] In the centre of the nebula lies a binary star, composed of a G-type star and a white dwarf.[3] Although it is commonly referred to as a planetary nebula, it has been suggested that the nebula wasn't created by a post-AGB star shedding its outer shells but it is interstellar medium photoionised by the passing binary system, leading also to the creation of the bow shock.[2][4]
| Emission nebula | |
|---|---|
| Planetary nebula | |
 | |
| Observation data: J2000.0 epoch | |
| Right ascension | 12h 53m 32.8s[1] |
| Declination | −22° 52′ 23″[1] |
| Distance | 400 ly |
| Apparent magnitude (V) | 9.69[1] |
| Apparent dimensions (V) | 12.87′[1] |
| Constellation | Hydra |
| Designations | PN G303.6+40.0, BD-22 3467, HIP 62905, SH 2-313, LW Hya |
The optical spectrum of the central star is dominated by a G8 III–IV star which travels through the interstellar medium with a transverse velocity of 150 km/s.[5] The star is estimated to have a radius of 1.5–3.5 R☉, indicating it is a subgiant star. It's projected rotational velocity is 55 ± 10 km/s, indicating it is rotating fast.[6] The star has a visual apparent magnitude of 9.6 and exhibits short term variability every 0.765 days, indicating this is its rotational period, and has the variable star designation LW Hydrae.[7]
When observed in ultraviolet wavelengths by the International Ultraviolet Explorer, a very hot companion star was discovered, which was categorised as a DAO white dwarf based on the strong absorption features of HI and He II.[8] Its effective temperature is estimated to be about 80,000 Kelvin and its mass to be 0.48 M☉, too low to form a planetary nebula.[2] Using the Hubble Space Telescope, the separation of the two stars was estimated to be between 0.08 and 0.14 arcseconds in 1998.[9]
Planetary nebulae with similar binary systems, comprising a fast rotating late-type subgiant or giant star and a very hot companion are referred to as having Abell 35-type nuclei.[10]
References
edit- ^ a b c d "PN A66 35". simbad.cds.unistra.fr. Retrieved 10 November 2024.
- ^ a b c Ziegler, M.; Rauch, T.; Werner, K.; Köppen, J.; Kruk, J. W. (December 2012). "BD–22°3467, a DAO-type star exciting the nebula Abell 35". Astronomy & Astrophysics. 548: A109. doi:10.1051/0004-6361/201219536.
- ^ Herald, J. E.; Bianchi, L. (20 November 2002). "The Binary Central Star of the Planetary Nebula A35". The Astrophysical Journal. 580 (1): 434–446. doi:10.1086/343034.
- ^ Frew, David J.; Parker, Quentin A. (2010). "Planetary Nebulae: Observational Properties, Mimics and Diagnostics". Publications of the Astronomical Society of Australia. 27 (2): 129–148. doi:10.1071/AS09040.
- ^ Jacoby, G. H. (March 1981). "The peculiar planetary nebula Abell 35". The Astrophysical Journal. 244: 903. doi:10.1086/158765.
- ^ Thevenin, F.; Jasniewicz, G. (1 April 1997). "Barium-rich G stars in the nuclei of the planetary nebulae Abell 35 and LoTr5". Astronomy and Astrophysics. 320: 913–919. Bibcode:1997A&A...320..913T. ISSN 0004-6361.
- ^ Gatti, A. A.; Drew, J. E.; Lumsden, S.; Marsh, T.; Moran, C.; Stetson, P. (11 November 1997). "A radial velocity study of the companion to the central star of Abell 35". Monthly Notices of the Royal Astronomical Society. 291 (4): 773–779. doi:10.1093/mnras/291.4.773.
- ^ Grewing, M.; Bianchi, Luciana (1 June 1988). "The nucleus of Abell 35: a hot companion to SAO 181201". ESA, Proceedings of the Celebratory Symposium on a Decade of UV Astronomy with the IUE Satellite. 2: 177–178. Bibcode:1988ESASP.281b.177G.
- ^ Gatti, A. A.; Drew, J. E.; Oudmaijer, R. D.; Marsh, T. R.; Lynas-Gray, A. E. (December 1998). "The separation of the stars in the binary nucleus of the planetary nebula Abell 35". Monthly Notices of the Royal Astronomical Society. 301 (2): L33–L37. doi:10.1046/j.1365-8711.1998.02166.x.
- ^ Bond, H. E.; Ciardullo, R.; Meakes, M. G. (1 January 1993). "The Abell 35-Type Planetary Nuclei". Planetary Nebulae: Proceedings of the 155 Symposium of the International Astronomical Union; Held in Innsbruck; Austria; July 13–17; 1992. 155: 397. Bibcode:1993IAUS..155..397B.