Physical properties and evolutionary states of binaries and variable stars observed by LAMOST

Abstract

About eighteen thousand known variables including eclipsing binaries were observed by LAMOST during the first stage of the spectroscopic survey from October 24, 2011 to July 16, 2017. Stellar atmospheric parameters for about eleven thousands of them were determined including the temperature (T), the gravitational acceleration (log g), the metallicity [Fe/H] and the radial velocity $V_{\\rm r}$. Those parameters are introduced in the paper. The locations of those variables including $\\delta$ Sct and $\\gamma$ Dor stars on the Log g-T diagram are presented where EA- and EW-type eclipsing binaries are also shown for comparison. Meanwhile, new photometric results on two special sample stars ROTSE1 J144111.82+382750.0 and CSS\\_J034112.5+035336 were obtained by follow-up observations. The former was originally found as a $\\delta$ Sct star with a period of 0.191291\\,days. However, the LAMOST parameters reveal that it is far beyond the red edge of pulsational instability trip of $\\delta$ Sct stars. By using those new photometric data, we detect that it is an EW-type eclipsing binary with an orbital period of 0.382583. As for CSS\\_J034112.5+035336, it was listed as an EW-type binary in VSX with a period of 0.285554\\,days. However, the LAMOST data showed that it is a special target because its temperature is very higher when compared with the short period. Our new photometric observations reveal it is a pulsating star rather than an EW-type binary. These results indicate that the LAMOST data are very useful to understand their physical properties and evolutionary states.