TY Coronae Borealis, also known as Ross 808, is a white dwarf in the constellation Corona Borealis. It is 107 light-years distant from Earth,[2] and has a dim apparent magnitude of 14.4.[3]

It is a pulsating white dwarf of the DAV (ZZ Ceti) type. The variation in the blue band is of 0.14 magnitudes, over a period of 15 minutes.[5] It was confirmed as a variable star in 1976, and now has the variable-star designation TY Coronae Borealis.[10] Being of this variable class, it has been a target for asteroseismic analyses, in attempt to derive its physical properties such as mass, radius and gravity.[9][11][8] However, it seems estimations of the stellar mass derived for this star using asteroseismology had been overestimated.[3]

TY Coronae Borealis has around 0.6 times the mass of the Sun[3] and a tiny diameter of only 1.3% that of the Sun.[7] It is a dim star, with 0.2% of the Sun's luminosity.[8] It has an effective temperature of about 11,000 K,[9] have taken 450 million years to cool to its temperature. This is also its age as a white dwarf.[6]

References

  1. ^ Bognár, Zs.; Paparó, M.; Sódor, Á.; Jenei, D. I.; Kalup, Cs.; Bertone, E.; Chavez-Dagostino, M.; Montgomery, M. H.; Gyõrffy, Á.; Molnár, L.; Ollé, H.; Pápics, P. I.; Plachy, E.; Verebélyi, E. (January 2019). "Wandering near the red edge: photometric observations of three cool ZZ Ceti stars". Monthly Notices of the Royal Astronomical Society. 482 (3): 4018–4031. arXiv:1810.09711. Bibcode:2019MNRAS.482.4018B. doi:10.1093/mnras/sty2884.
  2. ^ 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.
  3. ^ a b c d e Calcaferro, Leila M.; Córsico, Alejandro H.; Uzundag, Murat; Althaus, Leandro G.; Kepler, S. O.; Werner, Klaus (2024-11-01). "An analysis of spectroscopic, seismological, astrometric, and photometric masses of pulsating white dwarf stars". Astronomy & Astrophysics. 691: A194. arXiv:2409.03896. Bibcode:2024A&A...691A.194C. doi:10.1051/0004-6361/202450582. ISSN 0004-6361.
  4. ^ a b "TY CrB". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 5 December 2016.
  5. ^ a b Watson, Christopher (4 January 2010). "TY Coronae Borealis". AAVSO Website. American Association of Variable Star Observers. Retrieved 23 November 2014.
  6. ^ a b c Limoges, M. -M.; Bergeron, P.; Lépine, S. (2015-08-01). "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. ISSN 0067-0049.
  7. ^ a b Bédard, A.; Bergeron, P.; Fontaine, G. (2017-10-05). "Measurements of Physical Parameters of White Dwarfs: A Test of the Mass–Radius Relation". The Astrophysical Journal. 848 (1): 11. arXiv:1709.02324. Bibcode:2017ApJ...848...11B. doi:10.3847/1538-4357/aa8bb6. ISSN 0004-637X.
  8. ^ a b c Romero, A. D.; Córsico, A. H.; Althaus, L. G.; Kepler, S. O.; Castanheira, B. G.; Miller Bertolami, M. M. (2012-02-21). "Toward ensemble asteroseismology of ZZ Ceti stars with fully evolutionary models". Monthly Notices of the Royal Astronomical Society. 420 (2): 1462–1480. arXiv:1109.6682. Bibcode:2012MNRAS.420.1462R. doi:10.1111/j.1365-2966.2011.20134.x. ISSN 0035-8711.
  9. ^ a b c d Chen, Y H; Shu, H (2021-02-01). "Asteroseismology of the DAV star R808". Monthly Notices of the Royal Astronomical Society. 500 (4): 4703–4709. arXiv:2011.06918. doi:10.1093/mnras/staa3572. ISSN 0035-8711.
  10. ^ McGraw, John T.; Robinson, Edward L. (1976). "High-speed photometry of luminosity-variable DA dwarfs: R808, GD 99, and G 117-B15A". Astrophysical Journal Letters. 205: L155-58. Bibcode:1976ApJ...205L.155M. doi:10.1086/182112.
  11. ^ Bischoff-Kim, Agnès; Bell, Keaton J. (2024-07-12). "Constraints from Parallaxes and Average Period Spacings in the Asteroseismic Study of Eight Hydrogen-atmosphere Pulsating White Dwarfs". The Astrophysical Journal. 970 (1): 27. Bibcode:2024ApJ...970...27B. doi:10.3847/1538-4357/ad4edc. ISSN 0004-637X.
Allikas: http://en.wikipedia.org/wiki/TY_Coronae_Borealis
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