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Spectroscopic orbit of the ex-eclipsing binary SS Lacertae in the young open cluster NGC 7209
Lina Tomasella 1 and
Ulisse Munari 2
Received 5 February 1998 / Accepted 24 April 1998
The no-longer-eclipsing system SS Lac in the young open cluster NGC 7209 has been recently announced to show a constant radial velocity. Puzzled by this finding, we have monitored the system during 1997 obtaining 24 Echelle+CCD spectra over 8 orbital revolutions. Our spectra reveal a nice orbital motion with periodic splitting and merging of spectral lines from both components.
An accurate orbit has been derived, together with individual masses of the stars. SS Lac presents a moderately eccentric orbit and a probably full synchronization between stellar rotation and orbital revolution.
Key words: binaries: eclipsing binaries: spectroscopic stars: individual: SS Lacertae open clusters: individual: NGC 7209
Send offprint requests to: U. Munari
Online publication: June 18, 1998