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,[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 .