High-Amplitude gamma Doradus Variables. (arXiv:2009.09239v2 [astro-ph.SR] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Paunzen_E/0/1/0/all/0/1">Ernst Paunzen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bernhard_K/0/1/0/all/0/1">Klaus Bernhard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huemmerich_S/0/1/0/all/0/1">Stefan Huemmerich</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hambsch_F/0/1/0/all/0/1">Franz-Josef Hambsch</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lloyd_C/0/1/0/all/0/1">Christopher Lloyd</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Otero_S/0/1/0/all/0/1">Sebastian Otero</a>
According to most literature sources, the amplitude of the pulsational
variability observed in gamma Doradus stars does not exceed 0.1 mag in Johnson
V. We have analyzed fifteen high-amplitude gamma Doradus stars with photometric
peak-to-peak amplitudes well beyond this limit, with the aim of unraveling the
mechanisms behind the observed high amplitudes and investigating whether these
objects are in any way physically distinct from their low-amplitude
counterparts. We have calculated astrophysical parameters and investigated the
location of the high-amplitude gamma Doradus stars and a control sample of
fifteen low-amplitude objects in the log Teff versus log L diagram. Employing
survey data and our own observations, we analyzed the photometric variability
of our target stars using discrete Fourier transform. Correlations between the
observed primary frequencies, amplitudes and other parameters like effective
temperature and luminosity were investigated. The unusually high amplitudes of
the high-amplitude gamma Doradus stars can be explained by the superposition of
several base frequencies in interaction with their combination and overtone
frequencies. Although the maximum amplitude of the primary frequencies does not
exceed an amplitude of 0.1 mag, total light variability amplitudes of over 0.3
mag (V) can be attained in this way. Low- and high-amplitude gamma Doradus
stars do not appear to be physically distinct in any other respect than their
total variability amplitudes but merely represent two ends of the same, uniform
group of variables.
According to most literature sources, the amplitude of the pulsational
variability observed in gamma Doradus stars does not exceed 0.1 mag in Johnson
V. We have analyzed fifteen high-amplitude gamma Doradus stars with photometric
peak-to-peak amplitudes well beyond this limit, with the aim of unraveling the
mechanisms behind the observed high amplitudes and investigating whether these
objects are in any way physically distinct from their low-amplitude
counterparts. We have calculated astrophysical parameters and investigated the
location of the high-amplitude gamma Doradus stars and a control sample of
fifteen low-amplitude objects in the log Teff versus log L diagram. Employing
survey data and our own observations, we analyzed the photometric variability
of our target stars using discrete Fourier transform. Correlations between the
observed primary frequencies, amplitudes and other parameters like effective
temperature and luminosity were investigated. The unusually high amplitudes of
the high-amplitude gamma Doradus stars can be explained by the superposition of
several base frequencies in interaction with their combination and overtone
frequencies. Although the maximum amplitude of the primary frequencies does not
exceed an amplitude of 0.1 mag, total light variability amplitudes of over 0.3
mag (V) can be attained in this way. Low- and high-amplitude gamma Doradus
stars do not appear to be physically distinct in any other respect than their
total variability amplitudes but merely represent two ends of the same, uniform
group of variables.
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