V762 Cassiopeiae is a red supergiant and a variable star located about 2,500 light-years away in the Cassiopeia constellation. Its apparent magnitude vary between 5.82 and 5.95, which makes it faintly visible to the naked eye under dark skies. It is a relatively cool star with an average surface temperature of 3,869 K.
 The location of V762 Cassiopeiae | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 01h 16m 11.902s[1] |
| Declination | +71° 44′ 37.83″[1] |
| Apparent magnitude (V) | 5.82 – 5.95[2] |
| Characteristics | |
| Evolutionary stage | Red supergiant[3] |
| Spectral type | K5 I[3][2] |
| Variable type | Slow irregular variable[2] |
| Astrometry | |
| Radial velocity (Rv) | −21.37±0.91[1] km/s |
| Proper motion (μ) | RA: -1.658 mas/yr[1] Dec.: 1.791 mas/yr[1] |
| Parallax (π) | 1.3148 ± 0.0693 mas[1] |
| Distance | 2,500 ± 100 ly (760 ± 40 pc) |
| Details | |
| Mass | 16.9±2.2[4] M☉ |
| Radius | 265.7–272.3[5] R☉ |
| Luminosity | 14,970[5] L☉ |
| Temperature | 3869±145[3][5] K |
| Age | 10.0±1.6[4] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Characteristics
edit
V762 Cassiopeiae has a spectral classification of K0 I,[3] meaning that it is an evolved K-type red supergiant star. It is estimated to be ten million years old, has around 16.9 times the Sun's mass[4] and has expanded to 266 times the Sun's diameter. It radiates 15,000 times the solar luminosity from its photosphere at an effective temperature of 3869 K,[5] which gives it an orange-red hue, typical of red supergiants.[8] Parallax measurements from the Gaia spacecraft show that V762 Cassiopeiae is located 2,480 light-years away.[1] At the estimated distance, V762 Cassiopeiae's apparent brightness is diminished by 1.04 magnitudes due to interstellar extinction.[5]
Hipparcos satellite data showed that the star is variable, and because of that it was given the variable-star designation V762 Cassiopeiae, in 1999.[9] The variability amplitude in visible light is only about 0.1 magnitudes. The International Variable Star Index lists it as an irregular variable,[2] but the General Catalogue of Variable Stars (GCVS) classifies it as a BY Draconis star.[10] The designation of GCVS is likely erroneous, since BY Draconis variability is a characteristic of main sequence stars.[11]
Distance and titleholding
editSome websites claim V762 Cassiopeiae is the "farthest star visible to the naked eye", at a distance of 16,308 light-years.[12][13] This is inconsistent with parallax measurements from both Hipparcos, which found a parallax of 1.18±0.45 mas, corresponding to a distance of about 2,800 light-years,[14] and Gaia DR3, which lists a parallax of 1.3148±0.0693 mas, corresponding to a distance of about 2,500 light-years.[1][a] The websites claiming that V762 Cassiopeiae is the "farthest star visible to the naked eye" also do not cite any references for the distance of 16,308 light-years, making the origin of this value uncertain.
Notes
edit- ^ The distance (in parsecs) is equivalent to the inverse of the parallax (in arcseconds).
References
edit- ^ a b c d e f g Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c d "V0762 Cas". The International Variable Star Index. AAVSO. Retrieved 8 May 2024.
- ^ a b c d Messineo, M.; Brown, A. G. A. (2019-07-01). "A Catalog of Known Galactic K-M Stars of Class I Candidate Red Supergiants in Gaia DR2". The Astronomical Journal. 158 (1): 20. arXiv:1905.03744. Bibcode:2019AJ....158...20M. doi:10.3847/1538-3881/ab1cbd. ISSN 0004-6256. V762 Cassiopeiae's database entry at VizieR.
- ^ a b c Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (2011-01-01). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. ISSN 0035-8711. V762 Cassiopeiae's database entry at VizieR.
- ^ a b c d e Healy, Sarah; Horiuchi, Shunsaku; Molla, Marta Colomer; Milisavljevic, Dan; Tseng, Jeff; Bergin, Faith; Weil, Kathryn; Tanaka, Masaomi (2024-03-23). "Red Supergiant Candidates for Multimessenger Monitoring of the Next Galactic Supernova". Monthly Notices of the Royal Astronomical Society. 529 (4): 3630–3650. arXiv:2307.08785. doi:10.1093/mnras/stae738. ISSN 0035-8711.
- ^ "HD 7389". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 9 April 2024.
- ^ EAS (1997). "The HIPPARCOS and TYCHO catalogues". Astrometric and Photometric Star Catalogues Derived from the ESA Hipparcos Space Astrometry Mission. ESA SP Series. 1200. Noordwijk, Netherlands: ESA Publications Division. Bibcode:1997ESASP1200.....E. ISBN 9290923997. Retrieved 15 October 2022.
- ^ "The Colour of Stars". Australia National Telescope Facility. 6 March 2024. Retrieved 2024-05-27.
- ^ Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V.; Frolov, M. S.; Antipin, S. V.; Kireeva, N. N.; Pastukhova, E. N. (January 1999). "The 74th Special Name-list of Variable Stars" (PDF). Information Bulletin on Variable Stars. 4659: 1. Bibcode:1999IBVS.4659....1K. Retrieved 8 May 2024.
- ^ "Query= V762 Cas". General Catalogue of Variable Stars. Lomonosov Moscow State University. Retrieved 8 May 2024.
- ^ Chahal, Deepak; de Grijs, Richard; Kamath, Devika; Chen, Xiaodian (2022-07-06). "Statistics of BY Draconis Chromospheric Variable Stars". Monthly Notices of the Royal Astronomical Society. 514 (4): 4932–4943. arXiv:2206.05505. doi:10.1093/mnras/stac1660. ISSN 0035-8711.
- ^ "Farthest Star You Can See With The Unaided Eye". Cosmoknowledge. 2021-03-26. Retrieved 2024-04-11.
- ^ "How Far Back In Time Can We See With Our Naked Eye?". Big Think. 2021-05-17. Retrieved 2024-04-11.
- ^ "HIP 5926". VizieR. Centre de données astronomiques de Strasbourg. Retrieved 11 April 2024.