Visual Orbits of A- and F-stars in Spectroscopic Binaries

The fundamental parameters of eclipsing binary stars are used to test stellar evolutionary models by comparing the observed and predicted stellar parameters, such as mass, radius and temperature. However, most eclipsing binaries have short orbital periods, which implies that the stars probably interacted in their early phases and are currently subject to tidal forces. So, it is not clear how applicable the parameters of close binaries are to evolutionary models of single stars. The solution to this problem is to expand binary star studies to longer period systems that are widely separated and not interacting. This requires the determination of a visual orbit to estimate the orbital inclination, which is then combined with the spectroscopic elements to find masses. For my thesis project, we plan to determine the visual and spectroscopic orbits for 14 double-lined spectroscopic binaries by combining echelle spectroscopy from APO with long baseline interferometry from CHARA.











Image Credit: the CHARA array





A Photometric, Spectroscopic and Apsidal Motion Analysis of BW Aqr

Apsidal motion and fundamental parameters of eclipsing binary systems provide a test of stellar interiors and stellar evolution models. We completed a photometric and spectroscopic analysis of one such system, BW Aquarii. We modeled the K2 C3 light curve using ELC to determine several orbital and stellar parameters, then measured the eclipse times to determine updated apsidal motion parameters for the system. Furthermore, we obtained high resolution spectra of BW Aqr using the CHIRON echelle spectrograph on the CTIO 1.5m for radial velocity analysis. We then disentangled the spectra of each component using Doppler tomography and compared the individual spectra to BLUERED models to determine the atmospheric parameters of each component. Finally, we compared the combined photometric and spectroscopic results to the predictions of several stellar evolution models.





K2 C0 Eclipsing Binary near EPIC 202062176

We completed a photometric and light curve analysis of an eccentric eclipsing binary in the K2 Campaign 0 feld that resides in Sh 2-252E, a young star cluster embedded in an H II region. Because there dozens of stars in this embedded cluster fall within the Kepler aperture, we obtained spectra of the three brightest stars in the crowded aperture to identify which is the binary system. We found that none of these stars are components of the eclipsing binary system, which must be one of the fainter nearby stars. However, these bright cluster members all have remarkable spectra: Sh 2-252a (EPIC 202062176) is a B0.5 V star with razor sharp absorption lines, Sh 2-252b is a Herbig A0 star with disk-like emission lines, and Sh 2-252c is a pre-main sequence star with very red color.
Lester, K.V., Gies, D.R., & Guo, Z. 2016, AJ, 152, 194




My NASA/ADS publications can be found HERE.