The only well-studied red nova progenitor ( V1309 Sco ) was a contact binary with a 1.4-day period .
The prospects for searching for similar systems , as well as stellar merger candidates in general , are explored in this work .
The photospheric temperatures of 128 variables with periods P = 1.1 - 1.8 d classified as W UMa-type binaries are calculated using their colors listed in the SDSS catalog .
A selection of 15 contact binaries with similar temperatures and periods as the V1309 Sco progenitor is thus compiled .
The Kepler Eclipsing Binary Catalog is used to analyse systems with eclipse timing variations ( ETV ) possibly caused by changes of the orbital period .
Out of the 31 systems with parabolic ETV curves listed by Conroy et al .
( 2014 , AJ , 147 , 45 ) two could be contact binaries with a decreasing period and , therefore , potential stellar merger candidates .
Out of the 569 contact binaries in the OGLE field analysed by Kubiak et al .
( 2006 , AcA , 56 , 253 ) 14 systems have periods longer than 0.8 d and a statistically significant period decrease .