Deciphering the pulsations of G 29-38 with optical time series spectroscopy |
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| Authors: | Susan E Thompson M H van Kerkwijk J C Clemens |
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| Institution: | Department of Physics and Astronomy, University of Delaware, 217 Sharp Lab, Newark, DE 19716, USA;Department of Physics, Colorado College, Colorado Springs, CO 80903, USA;Department of Astronomy and Astrophysics, University of Toronto, 50 Saint George Street Toronto, ON M5S 3H4, Canada;Department of Physics and Astronomy, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA |
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| Abstract: | We present optical time series spectroscopy of the pulsating white dwarf star G 29-38 taken at the Very Large Telescope (VLT). By measuring the variations in brightness, Doppler shift and line shape of each spectrum, we explore the physics of pulsation and measure the spherical degree (?) of each stellar pulsation mode. We measure the physical motion of the g modes correlated with the brightness variations for three of the eight pulsation modes in this data set. The varying line shape reveals the spherical degree of the pulsations, an important quantity for properly modelling the interior of the star with asteroseismology. Performing fits to the Hβ, Hγ and Hδ lines, we quantify the changing shape of the line and compare them to models and previous time series spectroscopy of G 29-38. These VLT data confirm several ? identifications and add four new values, including an additional ?= 2 and a possible ?= 4. In total, from both sets of spectroscopy of G 29-38, eleven modes now have known spherical degrees. |
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| Keywords: | stars: individual: G 29-38 stars: oscillations white dwarfs |
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