W Virginis variable

File:Kappa Pavonis TESS lightcurve.png

W Virginis variables are a subclass of Type II Cepheids which exhibit pulsation periods between 10–20 days,{{cite journal | last=Wallerstein | first=G. | author-link=George Wallerstein | bibcode=2002PASP..114..689W | title=The Cepheids of Population II and Related Stars | journal=Publications of the Astronomical Society of the Pacific | volume=114 | pages=689–699 | year=2002 | issue=797 | doi=10.1086/341698 }} and are of spectral class F6 – K2.{{cite book | first=W. | last=Strohmeier | title=Variable Stars | publisher=Pergamon Press | year=1972 | bibcode=1972vast.book.....S | location=Oxford, New York }}{{cite journal | last1=Soszyński | first1=I. | last2=Udalski | first2=A. | last3=Szymański | first3=M. K. | last4=Kubiak | first4=M. | last5=Pietrzyński | first5=G. | last6=Wyrzykowski | first6=Ł. | last7=Szewczyk | first7=O. | last8=Ulaczyk | first8=K. | last9=Poleski | first9=R. | bibcode=2008AcA....58..293S | title=The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. II.Type II Cepheids and Anomalous Cepheids in the Large Magellanic Cloud | journal= Acta Astronomica| volume=58 | year=2008 | page=293 | arxiv=0811.3636 }}

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.{{cite book | last=Webb | first=Stephen | title=Measuring the Universe: The Cosmological Distance Ladder | publisher=Springer | year=1999 }}