Pulsation among TESS A and B stars reveals unexpected results. (arXiv:2001.04497v1 [astro-ph.SR])

Pulsation among TESS A and B stars reveals unexpected results. (arXiv:2001.04497v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Balona_L/0/1/0/all/0/1">Luis A Balona</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ozuyar_D/0/1/0/all/0/1">Dogus Ozuyar</a>

Classification of over 50000 TESS stars in sectors 1-18 has resulted in the
detection of 766 pulsating main sequence B stars as well as over 5000 $delta$
Scuti, 2300 $gamma$ Doradus and 114 roAp candidates. It is found that a
distinct group of $beta$ Cephei stars, defined as B stars with frequencies
greater than 2.5 d$^{-1}$ and predicted by models, does not exist. Instead,
high frequencies are to be found over the whole B-star range, eventually
merging with $delta$ Scuti stars. The cool B stars pulsating in high
frequencies are the Maia variables. It is shown that Maia variables are not
rapidly-rotating $beta$ Cephei or SPB stars. In the region where $beta$
Cephei variables are found, the proportion of pulsating stars is larger and
amplitudes are higher and a considerable fraction pulsate in a single mode and
low rotation rate. There is no distinct SPB instability region. Stars pulsating
sole in low frequencies are found among all B stars. At most, only one-third of
B stars appear to pulsate. These results, as well as the fact that a large
fraction of A and B stars show rotational modulation, indicate a need for a
revision of current ideas regarding stars with radiative envelopes.

Classification of over 50000 TESS stars in sectors 1-18 has resulted in the
detection of 766 pulsating main sequence B stars as well as over 5000 $delta$
Scuti, 2300 $gamma$ Doradus and 114 roAp candidates. It is found that a
distinct group of $beta$ Cephei stars, defined as B stars with frequencies
greater than 2.5 d$^{-1}$ and predicted by models, does not exist. Instead,
high frequencies are to be found over the whole B-star range, eventually
merging with $delta$ Scuti stars. The cool B stars pulsating in high
frequencies are the Maia variables. It is shown that Maia variables are not
rapidly-rotating $beta$ Cephei or SPB stars. In the region where $beta$
Cephei variables are found, the proportion of pulsating stars is larger and
amplitudes are higher and a considerable fraction pulsate in a single mode and
low rotation rate. There is no distinct SPB instability region. Stars pulsating
sole in low frequencies are found among all B stars. At most, only one-third of
B stars appear to pulsate. These results, as well as the fact that a large
fraction of A and B stars show rotational modulation, indicate a need for a
revision of current ideas regarding stars with radiative envelopes.

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