Observations of Be Disk Building: Optical Spectra of NW Serpentis (HD 168797) over 35 days
Dept. of Physics & Astronomy, Vanderbilt University, Nashville, TN, USA, and Dept. of Physics, Fisk University, Nashville, TN, USA
Dept. of Physics, Lehigh University, Bethlehem, PA, USA
Dept. of Physics, Lehigh University, Bethlehem, PA, USA
CHARA, Georgia State University, Atlanta, GA, USA
Dept. of Physics, Lehigh University, Bethlehem, PA, USA
Dept. of Physics, Lehigh University, Bethlehem, PA, USA
Abstract
The classical Be star NW Serpentis (HD 168797) is part of the CoRoT field and has long been studied photometrically and is known to have multi-periodic pulsational modes. Such pulsations are thought to be a way to generate the Be equatorial circumstellar disk. In an earlier survey, we identified this star as a possible non-radial pulsator and a known B Be variable. During Fall 2008, we obtained 23 spectra over 35 nights in the Halpha region. During this time, we observed Halpha to go from purely photospheric absorption to double-peaked emission then ”fade” back toward photospheric absorption. We present our determination of stellar parameters, our analysis of the circumstellar disk construction, and the possibility of a binary companion. These observations also suggest that frequent observations of Be stars known to be non-radial pulsators may yield more opportunities to study the disk-building phenomenon and thus assist in constraining theoretical models of disk generation.