Editing Variable star (section)

====Pulsating white dwarfs====
{{Main|Pulsating white dwarf}}
These non-radially pulsating stars have short periods of hundreds to thousands of seconds with tiny fluctuations of 0.001 to 0.2 magnitudes. Known types of pulsating white dwarf (or pre-white dwarf) include the ''DAV'', or ''[[ZZ Ceti]]'', stars, with hydrogen-dominated atmospheres and the spectral type DA;<ref name="physrev">{{cite journal|bibcode=1990RPPh...53..837K|title=REVIEW: Physics of white dwarf stars|journal=Reports on Progress in Physics|volume=53|issue=7|pages=837|last1=Koester|first1=D.|last2=Chanmugam|first2=G.|year=1990|doi=10.1088/0034-4885/53/7/001|s2cid=122582479|url=https://semanticscholar.org/paper/fde3294fc2ec8d89f95f7c3eaad91e7b0416601c}}</ref> ''DBV'', or ''[[V777 Her]]'', stars, with helium-dominated atmospheres and the spectral type DB;<ref name="wden">{{cite book|bibcode=2002eaa..book.....M|isbn=0-333-75088-8|title=Encyclopedia of Astronomy and Astrophysics|last1=Murdin|first1=Paul|year=2002}}</ref> and ''[[GW Vir]]'' stars, with atmospheres dominated by helium, carbon, and oxygen. GW Vir stars may be subdivided into ''DOV'' and ''PNNV'' stars.<ref name="quirion">{{cite journal|bibcode=2007ApJS..171..219Q|title=Mapping the Instability Domains of GW Vir Stars in the Effective Temperature-Surface Gravity Diagram|journal=The Astrophysical Journal Supplement Series|volume=171|issue=1|pages=219–248|last1=Quirion|first1=P.-O.|last2=Fontaine|first2=G.|last3=Brassard|first3=P.|year=2007|doi=10.1086/513870|doi-access=free}}</ref><ref>{{cite journal|bibcode=2004A&A...426L..45N|title=Detection of non-radial g-mode pulsations in the newly discovered PG 1159 star HE 1429-1209|journal=Astronomy and Astrophysics|volume=426|issue=2|pages=L45|last1=Nagel|first1=T.|last2=Werner|first2=K.|year=2004|doi=10.1051/0004-6361:200400079|arxiv = astro-ph/0409243 |s2cid=9481357}}</ref>