| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hercules |
| Right ascension | 16h 28m 25.0031s [1] |
| Declination | +36° 46′ 15.847″ [1] |
| Apparent magnitude (V) | 13.83 [2] |
| Characteristics | |
| Evolutionary stage | white dwarf |
| Spectral type | DZA5.5 [3] |
| Astrometry | |
| Proper motion (μ) |
RA: −494.230(15)
mas/
yr
[1] Dec.: 746.698(18) mas/ yr [1] |
| Parallax (π) | 62.9109 ± 0.0143 mas [1] |
| Distance | 51.84 ± 0.01
ly (15.895 ± 0.004 pc) |
| Absolute magnitude (MV) | +13.01 [4] |
| Details | |
| Mass | 0.58±0.03 [5] M☉ |
| Luminosity | 0.0007 [5] L☉ |
| Surface gravity (log g) | 7.76 [6] cgs |
| Temperature | 8,100 [7] K |
| Age | 1.02 [6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Ross 640 is a white dwarf star in the northern constellation of Hercules, positioned near the constellation border with Corona Borealis. With an apparent visual magnitude of 13.83, [2] it is too faint to be visible to the naked eye. Its trigonometric parallax from the Gaia mission is 62.9 ″, [1] corresponding to a distance of 52 light-years (15.9 parsecs).
This compact star has a stellar classification of DZA5.5, indicating a metal-rich atmosphere accompanied by weaker lines of hydrogen. [3] A detailed analysis of its spectrum revealed that Ross 640 is a relatively cool white dwarf with an effective temperature of approximately 8,100 K, which means that it has been in the white dwarf phase for slightly more than 1 billion years. [7] Ross 640 has a spectrum characterized by hydrogen Balmer lines in the visible and very strong ionized magnesium lines in the ultraviolet. [9] The presence of heavy elements in the photosphere of Ross 640 indicates that it recently accreted rocky debris from its planetary system.
References
- ^ a b c d e 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 Bergeron, P.; Leggett, S. K.; Ruiz, María Teresa (2001). "Photometric and Spectroscopic Analysis of Cool White Dwarfs with Trigonometric Parallax Measurements". The Astrophysical Journal Supplement Series. 133 (2): 413–450. arXiv: astro-ph/0011286. Bibcode: 2001ApJS..133..413B. doi: 10.1086/320356. ISSN 0067-0049. S2CID 15511301.
- ^ a b Wesemael, F.; et al. (1993). "An atlas of optical spectra of white-dwarf stars". Publications of the Astronomical Society of the Pacific. 105: 761. Bibcode: 1993PASP..105..761W. doi: 10.1086/133228. S2CID 122605705.
- ^ Limoges, M. -M; Bergeron, P.; Lépine, S. (2015). "Physical Properties of the Current Census of Northern White Dwarfs within 40 pc of the Sun". The Astrophysical Journal Supplement Series. 219 (2): 19. arXiv: 1505.02297. Bibcode: 2015ApJS..219...19L. doi: 10.1088/0067-0049/219/2/19. S2CID 118494290.
- ^ a b Toonen, S.; Hollands, M.; Gänsicke, B. T.; Boekholt, T. (2017). "The binarity of the local white dwarf population". Astronomy and Astrophysics. 602: A16. arXiv: 1703.06893. Bibcode: 2017A&A...602A..16T. doi: 10.1051/0004-6361/201629978. S2CID 12367523.
- ^ a b Holberg, J. B.; Oswalt, T. D.; Sion, E. M.; McCook, G. P. (2016). "The 25 parsec local white dwarf population". Monthly Notices of the Royal Astronomical Society. 462 (3): 2295. arXiv: 1606.01236. Bibcode: 2016MNRAS.462.2295H. doi: 10.1093/mnras/stw1357. hdl: 10150/621732.
- ^ a b Blouin, S.; Dufour, P.; Allard, N. F. (23 August 2018). "A New Generation of Cool White Dwarf Atmosphere Models. I. Theoretical Framework and Applications to DZ Stars". The Astrophysical Journal. 863 (2): 184. arXiv: 1807.06616. Bibcode: 2018ApJ...863..184B. doi: 10.3847/1538-4357/aad4a9. S2CID 119347098.
- ^ "ross 640". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-08-20.
- ^ Zeidler-K.T., E.-M.; Weidemann, V.; Koester, D. (1986). "Metal abundances in helium-rich white dwarf atmospheres". Astronomy & Astrophysics. 155 (2): 356–370. Bibcode: 1986A&A...155..356Z.
