AAVSO: American Association of Variable Star Observers

β Cepheid and Mira Variable Stars: A Spectral Analysis (Abstract)

Volume 47 number 1 (2019)

Jesse D’Shawn Harris
22792 U.S. Highway 23 N, Duffield, VA 24244; jdh3uf@uvawise.edu
Lucian Undreiu
121 Beverly Avenue, Wise, VA, 24293; lundreiu@hotmail.com

Abstract

(Abstract only) The purpose of this project is to investigate and compare the spectra of several variable stars belonging to two classes, β Cephei and Mira, while trying to correlate our observations with the photometric survey maintained by AAVSO. For this study we have used a SBIG STT 8300 CCD camera, in conjunction with an LHIRES III Spectrograph that was attached to a 16-inch Meade SCT telescope. The short pulsation periods (0.1–0.3 day) of β Cephei variables enabled us to follow their evolution through the entire cycle of pulsation. The identification of H Balmer and neutral He lines, which are originating in the upper atmospheric layers, confirms the spectral class (early B-type). The β Cephei intricate dynamics of the pulsation mechanism are revealed by the changes in the width of strong spectral lines, as well as by the line doubling. BW Vulpelculae is of particular interest, due to its large amplitude of pulsation, reflected in the variability in its spectrum with progression through its period. Mira variables are cool, red giants, pulsating slowly (>100 days), while having large fluctuations in brightness.