Spectroscopic and photometric analysis of NSV 24512: an early-type eclipsing binary embedded in a dust cloud★

Abstract

We present differential V-band photometric observations and the first radial velocities of NSV 24512, which is embedded in the Serpens star-forming region. This double-lined system has an eccentric orbit with an eccentricity of 0.193. The system is a member of visual double star ADS 11410AB with a separation of about 0.3 arcsec and an apparent visual magnitude difference of 0.125 mag; we find that the fainter component (component B) is responsible for the periodic light variation. Therefore, we subtracted the light contribution of component A from the total light. The V-band photometric data and radial velocities were then analysed simultaneously using the Wilson–Devinney program. From the blue-wavelength spectroscopic observations and radial velocities, we classify the primary and secondary components as B8V and B9V stars, respectively. The masses and radii of the component stars have been derived as 3.68 ± 0.05 and 3.36 ± 0.04 M⊙ and 3.21 ± 0.05 and 2.93 ± 0.05 R⊙, respectively. Comparison with theoretical evolutionary models indicates that both components are pre-main-sequence stars with an age of about 2.1 Myr. The projected rotational velocities of the components measured by us are much smaller than the synchronous rotational velocities. The high asynchronism is further evidence of the very young age of the system. Using the radiative properties of the stars, we have redetermined the distance to NSV 24512 as 247 ± 5 pc, which is in good agreement with, and more precise than, previous determinations. Adopting the same interstellar extinction and distance, we classify component A to be of spectral type B7, if it is a single star.