White drawf star in the northern constellation of Hercules
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, it is too faint to be visible to the naked eye. Its trigonometric parallax from the Gaia ″ , 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. 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. Ross 640 has a spectrum characterized by hydrogen Balmer lines in the visible and very strong ionized magnesium lines in the ultraviolet. The presence of heavy elements in the photosphere of Ross 640 indicates that it recently accreted rocky debris from its planetary system.
References
^ 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 .
^ 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 .
^ 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 .
^ 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 .
^ 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 .
^ 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 .
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