W Hydrae
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hydra |
| Right ascension | Template:RA |
| Declination | Template:DEC |
| Apparent magnitude (V) | 7.7 - 11.6[2] |
| Characteristics | |
| Spectral type | M7.5e-M9ep[3] |
| Apparent magnitude (J) | −1.7[4] |
| Variable type | Mira |
| Astrometry | |
| Parallax (π) | 10.18±2.36 mas[5] |
| Distance | 320+98 −59 ly (98+30 −18 pc)[5] |
| Details | |
| Mass | 2.14+1.07 −0.71[6] M☉ |
| Radius | Template:Solar radius calculator+134 −80[7][a] R☉ |
| Luminosity | 9,290+2,460 −1,940[6] L☉ |
| Temperature | 3,000[6] K |
| Other designations | |
| W Hya, CCDM J13491−2822A, HD 120285, RAFGL 1650, CPD−27°4792, HIP 67419, SAO 181981, AAVSO 1343-27, IRAS 13462-2807, GC 18659, TYC 6728-19-1. | |
| Database references | |
| SIMBAD | data |
W Hydrae is a Mira-type variable star in the constellation Hydra. The star is nearly located within the Solar neighborhood, at 320 light years from the Solar System. It has a visual apparent magnitude range of 5.6 to 10. In the near-infrared J band it has a magnitude of -1.7,[4] is the 7th brightest star in the night sky, and is even brighter than Sirius.
Water masers and dust

The star also shows signs of intense water emissions, indicative of the presence of a wide disk of dust and water vapour.[8] Such emissions cover a zone spanning between 10.7 Astronomical Units (within Saturn's orbital zone) and 1.2 parsecs (or nearly 247,500 Astronomical Units, as far away as the Oort Cloud in Solar System).
Notes
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- ^ Radius calculated using a distance of 98+30
−18 parsecs and an angular diameter of 41.4 milliarcseconds (0.041 arcsec). 98 • 0.041 = diameter of 4.06 AU, which is multiplied by 107.5 to convert from AU to R☉.
References
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- ^ Page Module:Citation/CS1/styles.css has no content."Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
- ^ Page Module:Citation/CS1/styles.css has no content."GCVS Query=W Hya". General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2012-08-22.
- ^ Page Module:Citation/CS1/styles.css has no content.Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
- ^ a b Page Module:Citation/CS1/styles.css has no content."V* W Hya". SIMBAD Astronomical Database. Retrieved 2012-08-21.
- ^ a b Page Module:Citation/CS1/styles.css has no content.Vlemmings, W. H. T.; Van Langevelde, H. J.; Diamond, P. J.; Habing, H. J.; Schilizzi, R. T. (2003). "VLBI astrometry of circumstellar OH masers: Proper motions and parallaxes of four AGB stars". Astronomy & Astrophysics. 407: 213–224. arXiv:astro-ph/0305405. Bibcode:2003A&A...407..213V. doi:10.1051/0004-6361:20030766. S2CID 11505142.
- ^ a b c Page Module:Citation/CS1/styles.css has no content.Takeuti, Mine; Nakagawa, Akiharu; Kurayama, Tomoharu; Honma, Mareki (2013). "A Method to Estimate the Masses of Asymptotic Giant Branch Variable Stars". Publications of the Astronomical Society of Japan. 65 (3): 60. Bibcode:2013PASJ...65...60T. doi:10.1093/pasj/65.3.60.
- ^ Page Module:Citation/CS1/styles.css has no content.Ohnaka, K.; Wong, K. T.; Weigelt, G.; Hofmann, K.-H. (November 2024). "Contemporaneous high-angular-resolution imaging of the AGB star W Hya in vibrationally excited H 2 O lines and visible polarized light with ALMA and VLT/SPHERE-ZIMPOL". Astronomy & Astrophysics. 691: L14. arXiv:2411.09759. doi:10.1051/0004-6361/202451977. ISSN 0004-6361.
- ^ Page Module:Citation/CS1/styles.css has no content.Zubko & Elitzur, Moshe (2000). "Water and Dust Emission from W Hydrae". The Astrophysical Journal. 544 (2): 137–140. arXiv:astro-ph/0009440. Bibcode:2000ApJ...544L.137Z. doi:10.1086/317317. S2CID 17702515.
External links
- AAVSO Variable Star of the Month. April 2008: W Hya
- W Hya[permanent dead link] at AAVSO (chart #8585EPX)