Informace o publikaci

The search for roAp stars: null results and new candidates from Stromgren-Crawford photometry

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PAUNZEN Ernst HANDLER Gerald HOŇKOVÁ Kateřina JURÝŠEK Jakub MAŠEK Martin DRÓŻDŻ Marek JANÍK Jan OGLOZA Waldemar HERMANSSON Lars JOHANSSON Mats JELÍNEK Martin SKARKA Marek ZEJDA Miloslav

Rok publikování 2018
Druh Článek v odborném periodiku
Časopis / Zdroj Research in Astronomy and Astrophysics
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
www http://dx.doi.org/10.1088/1674-4527/18/11/135
Doi http://dx.doi.org/10.1088/1674-4527/18/11/135
Klíčová slova stars: chemically peculiar; stars: early-type; stars: variables: general; techniques: photometric
Popis The rapidly oscillating Ap (roAp) stars exhibit pulsational photometric and/or radial velocity variations on time scales of several minutes, which are essential to test current pulsation models as well as our assumptions of atmospheric structure characteristics. In addition, their chemical peculiarity makes them very interesting for probing stellar formation and evolution in the presence of a global magnetic field. To date, a limited number of only 61 roAp stars is known to show photometric variability. On the other hand, a literature survey yields 619 unique stars that have unsuccessfully been searched for variability of this kind. Stromgren-Crawford uvby beta photometry of stars from both subgroups was used to investigate whether there is a selection bias for the investigated stars. We also present new photometric measurements (202 hours on 59 different nights) of 55 roAp candidates. We did not detect any new roAp star. Although our detection limits are comparable to other surveys, we also did not find pulsations in the known roAp star HD 12098, which may be a consequence of temporal amplitude changes. On the other hand, we do find some evidence for photometric variability of beta CrB at its spectroscopically derived pulsation period. From the uvby beta photometry we conclude that the blue border of the roAp instability strip appears observationally well defined, whereas the red border is rather poorly known and studied. Within these boundaries, a total of 4646 candidates were identified which appear worth investigating for short-term pulsational variability.
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