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@article{1510477,
author = {Paunzen, Ernst and Bernhard, Klaus and Hummerich, Stefan and Janík, Jan and Semenko, Evgenij and Yakunin, Iliya},
article_location = {Les Ulis},
article_number = {JAN 30 2019},
doi = {http://dx.doi.org/10.1051/0004-6361/201833098},
keywords = {stars: horizontal-branch; starspots; diffusion; techniques: photometric},
language = {eng},
issn = {1432-0746},
journal = {ASTRONOMY & ASTROPHYSICS},
title = {Search for stellar spots in field blue horizontal-branch stars},
url = {https://www.aanda.org/articles/aa/abs/2019/02/aa33098-18/aa33098-18.html},
volume = {622},
year = {2019}
}
TY - JOUR
ID - 1510477
AU - Paunzen, Ernst - Bernhard, Klaus - Hummerich, Stefan - Janík, Jan - Semenko, Evgenij - Yakunin, Iliya
PY - 2019
TI - Search for stellar spots in field blue horizontal-branch stars
JF - ASTRONOMY & ASTROPHYSICS
VL - 622
IS - JAN 30 2019
SP - 77-82
EP - 77-82
PB - EDP SCIENCES S A
SN - 14320746
KW - stars: horizontal-branch
KW - starspots
KW - diffusion
KW - techniques: photometric
UR - https://www.aanda.org/articles/aa/abs/2019/02/aa33098-18/aa33098-18.html
L2 - https://www.aanda.org/articles/aa/abs/2019/02/aa33098-18/aa33098-18.html
N2 - Context. Blue horizontal-branch stars are Population II objects which are burning helium in their core and possess a hydrogen-burning shell and radiative envelope. Because of their low rotational velocities, diffusion has been predicted to work in their atmospheres. In many respects, blue horizontal-branch stars closely resemble the magnetic chemically peculiar stars of the upper main sequence, which show photometric variability caused by abundance spots on their surfaces. These spots are thought to be caused by diffusion and the presence of a stable magnetic field. However, the latter does not seem to be axiomatic. Aims. We searched for rotationally induced variability in 30 well-established bright field blue horizontal-branch stars in the solar neighbourhood and searched the literature for magnetic fields measurements of our targets. Methods. We employed archival photometric time series data from the All Sky Automated Survey (ASAS), All-Sky Automated Survey for Supernovae (ASAS-SN), and Wide Angle Search for Planets (SuperWASP) surveys. The data were carefully reduced and processed, and a time series analysis was applied using several different techniques. We also synthesized existing photometric and spectroscopic data of magnetic chemically peculiar stars in order to study possible different surface characteristics producing lower amplitudes. Results. In the accuracy limit of the employed data, no significant variability signals were found in our sample stars. The resulting upper limits for variability are given. Conclusions. We conclude that either no stellar surface spots are present in field blue horizontal-branch stars, or their characteristics (contrast, total area, and involved elements) are not sufficient to produce amplitudes larger than a few millimagnitudes in the optical wavelength region. New detailed models taking into account the elemental abundance pattern of blue horizontal-branch stars are needed to synthesize light curves for a comparison with our results.
ER -
PAUNZEN, Ernst, Klaus BERNHARD, Stefan HUMMERICH, Jan JANÍK, Evgenij SEMENKO a Iliya YAKUNIN. Search for stellar spots in field blue horizontal-branch stars. Online. \textit{ASTRONOMY \&{} ASTROPHYSICS}. Les Ulis: EDP SCIENCES S A, 2019, roč.~622, JAN 30 2019, s.~77-82. ISSN~1432-0746. Dostupné z: https://dx.doi.org/10.1051/0004-6361/201833098. [citováno 2024-04-24]
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