Pulsating white dwarf

"V777 Herculis star" redirects here. For the star, see GD 358.

A pulsating white dwarf is a white dwarf star whose luminosity varies due to non-radial gravity wave pulsations within itself. Known types of pulsating white dwarfs include DAV, or ZZ Ceti, stars, with hydrogen-dominated atmospheres and the spectral type DA;[1] DBV, or V777 Her, stars, with helium-dominated atmospheres and the spectral type DB;[2] and GW Vir stars, with atmospheres dominated by helium, carbon, and oxygen, and the spectral type PG 1159. (Some authors also include non-PG 1159 stars in the class of GW Vir stars.) GW Vir stars may be subdivided into DOV and PNNV stars;[3][4] they are not, strictly speaking, white dwarfs but pre-white dwarfs which have not yet reached the white dwarf region on the Hertzsprung-Russell diagram.[5][6] A subtype of DQV stars, with carbon-dominated atmospheres, has also been proposed,[7] and in May 2012, the first extremely low mass variable (ELMV) white dwarf was reported.[8]

These variables all exhibit small (1%–30%) variations in light output, arising from a superposition of vibrational modes with periods of hundreds to thousands of seconds. Observation of these variations gives asteroseismological evidence about the interiors of white dwarfs.[9]

Types of pulsating white dwarf[4][7][8][10]
DAV (GCVS: ZZA) DA spectral type, having only hydrogen absorption lines in its spectrum
DBV (GCVS: ZZB) DB spectral type, having only helium absorption lines in its spectrum
GW Vir (GCVS: ZZO) Atmosphere mostly C, He and O;
may be divided into DOV and PNNV stars
DQV DQ spectral type; hot, carbon-dominated atmosphere
ELMV DA spectral type;
  1. ^ Koester & Chanmugam 1990, p. 891–895.
  2. ^ Murdin, Paul, ed. (2001). Encyclopedia of Astronomy and Astrophysics. Bristol: Nature Publishing Group. p. 3525. ISBN 978-0-333-75088-9.
  3. ^ Nagel, T.; Werner, K. (1 November 2004). "Detection of non-radial g-mode pulsations in the newly discovered PG 1159 star HE 1429-1209". Astronomy and Astrophysics. 426 (2): L45–L48. arXiv:astro-ph/0409243. Bibcode:2004A&A...426L..45N. doi:10.1051/0004-6361:200400079. ISSN 0004-6361. S2CID 9481357. §1.
  4. ^ a b Quirion, Fontaine & Brassard 2007, §1.1, 1.2.
  5. ^ Quirion, Fontaine & Brassard 2007, §1.1.
  6. ^ Cite error: The named reference obrien was invoked but never defined (see the help page).
  7. ^ a b Montgomery, M. H.; Williams, Kurtis A.; Winget, D. E.; Dufour, Patrick; DeGennaro, Steven; Liebert, James (2008). "SDSS J142625.71+575218.3: A Prototype for a New Class of Variable White Dwarf". The Astrophysical Journal Letters. 678 (1): L51. arXiv:0803.2646. Bibcode:2008ApJ...678L..51M. doi:10.1086/588286. ISSN 1538-4357. S2CID 15385909.
  8. ^ a b Hermes, J. J.; Montgomery, M. H.; Winget, D. E.; Brown, Warren R.; Kilic, Mukremin; Kenyon, Scott J. (1 May 2012). "SDSS J184037.78+642312.3: The First Pulsating Extremely Low Mass White Dwarf". The Astrophysical Journal Letters. 750 (2): L28. arXiv:1204.1338. Bibcode:2012ApJ...750L..28H. doi:10.1088/2041-8205/750/2/L28. ISSN 0004-637X. S2CID 119188878.
  9. ^ Winget, D. E. (1998). "Asteroseismology of white dwarf stars". Journal of Physics: Condensed Matter. 10 (49): 11247–11261. Bibcode:1998JPCM...1011247W. doi:10.1088/0953-8984/10/49/014. ISSN 0953-8984. S2CID 250749380.
  10. ^ Association Française des Observateurs d'Etoiles Variables. "ZZ Ceti variables". Centre de Données astronomiques de Strasbourg. Archived from the original on 2007-02-05. Retrieved 2007-06-06.