W Virginis variable

W Virginis variables are a subclass of Type II Cepheids which exhibit pulsation periods between 10–20 days,^[1] and are of spectral class F6 – K2.^[2]^[3]

They were first recognized as being distinct from classical Cepheids by Walter Baade in 1942, in a study of Cepheids in the Andromeda Galaxy that proposed that stars in that galaxy were of two populations.^[4]

References

^ Wallerstein, G., "The Cepheids of Population II and Related Stars", Publications of the Astronomical Society of the Pacific, 114 p.689–699 (2002)
^ W. Strohmeier, Variable Stars, Pergamon (1972)
^ Soszyński, I.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Wyrzykowski, Ł.; Szewczyk, O.; Ulaczyk, K.; Poleski, R. "The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. II.Type II Cepheids and Anomalous Cepheids in the Large Magellanic Cloud", Acta A., vol 58 (2008)
^ Webb, Stephen, Measuring the Universe: The Cosmological Distance Ladder, Springer, (1999)

External links

AAVSO Variable Star of the Month. W Virginis: Spring 2003 PDF / HTML
OGLE Atlas of Variable Star Light Curves - W Virginis stars

Variable stars

Pulsating

Cepheids and cepheid-like	Type I (Classical cepheids, Delta Scuti) Type II (BL Herculis, W Virginis, RV Tauri) RR Lyrae Rapidly oscillating Ap SX Phoenicis
Blue-white with early spectra	Alpha Cygni Beta Cephei Slowly pulsating B-type PV Telescopii Blue large-amplitude pulsator
Long-period	Mira Semiregular Slow irregular
Other	Gamma Doradus Solar-like oscillations White dwarf

Eruptive

Protostar and PMS	Herbig Ae/Be Orion FU Orionis T Tauri
Giants and supergiants	Luminous blue variable R Coronae Borealis (DY Persei) Yellow hypergiant
Eruptive binary	Double periodic FS Canis Majoris RS Canum Venaticorum
Other	Flare Gamma Cassiopeiae Lambda Eridani Wolf–Rayet