Editing Cepheid variable (section)

=== Double-mode Cepheids ===
A small proportion of Cepheid variables have been observed to pulsate in two modes at the same time, usually the fundamental and first overtone, occasionally the second overtone.<ref name=smolec>{{cite journal|bibcode=2008AcA....58..233S|arxiv=0809.1986|title=Double-Mode Classical Cepheid Models, Revisited|journal=[[Acta Astronomica]]|volume=58|pages=233|last1=Smolec|first1=R.|last2=Moskalik|first2=P.|year=2008}}</ref> A very small number pulsate in three modes, or an unusual combination of modes including higher overtones.<ref>{{cite journal|bibcode=2008AcA....58..153S|arxiv=0807.4182|title=The Optical Gravitational Lensing Experiment. Triple-Mode and 1O/3O Double-Mode Cepheids in the Large Magellanic Cloud|journal=[[Acta Astronomica]]|volume=58|pages=153 |last1=Soszynski|first1=I.|last2=Poleski|first2=R.|last3=Udalski|first3=A.|last4=Kubiak|first4=M.|last5=Szymanski|first5=M. K.|last6=Pietrzynski|first6=G.|last7=Wyrzykowski|first7=L.|last8=Szewczyk|first8=O.|last9=Ulaczyk|first9=K.|year=2008}}</ref>