Search for stellar spots in field blue horizontal-branch stars

J 2019

Search for stellar spots in field blue horizontal-branch stars

PAUNZEN, Ernst; Klaus BERNHARD; Stefan HUMMERICH; Jan JANÍK; Evgenij SEMENKO et al.

Základní údaje

Originální název

Search for stellar spots in field blue horizontal-branch stars

Autoři

PAUNZEN, Ernst; Klaus BERNHARD; Stefan HUMMERICH; Jan JANÍK ; Evgenij SEMENKO a Iliya YAKUNIN

Vydání

ASTRONOMY & ASTROPHYSICS, Les Ulis, EDP SCIENCES S A, 2019, 1432-0746

Další údaje

Jazyk

angličtina

Typ výsledku

Článek v odborném periodiku

Obor

10308 Astronomy

Stát vydavatele

Francie

Utajení

není předmětem státního či obchodního tajemství

Odkazy

Full Text

Označené pro přenos do RIV

Ano

Kód RIV

RIV/00216224:14310/19:00107325

Organizační jednotka

Přírodovědecká fakulta

Klíčová slova anglicky

stars: horizontal-branch; starspots; diffusion; techniques: photometric

Štítky

rivok

Příznaky

Mezinárodní význam, Recenzováno

Změněno: 17. 3. 2020 13:01, Mgr. Marie Novosadová Šípková, DiS.

Anotace

V originále

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.

Návaznosti

ED3.2.00/08.0144, projekt VaV

Název: CERIT Scientific Cloud

GA16-01116S, projekt VaV

Název: Atmosféry a okolohvězdné prostředí magnetických horkých hvězd

Investor: Grantová agentura ČR, Atmosféry a okolohvězdné prostředí magnetických horkých hvězd

7AMB17AT030, projekt VaV

Název: Analýza hvězd se skvrnami pomocí kvalitních pozorovacích dat

Investor: Ministerstvo školství, mládeže a tělovýchovy ČR, Analýza hvězd se skvrnami pomocí kvalitních pozorovacích dat

Citovat

PAUNZEN, Ernst; Klaus BERNHARD; Stefan HUMMERICH; Jan JANÍK; Evgenij SEMENKO a Iliya YAKUNIN. Search for stellar spots in field blue horizontal-branch stars. ASTRONOMY & ASTROPHYSICS. Les Ulis: EDP SCIENCES S A, 2019, roč. 622, JAN 30 2019, s. 77-82. ISSN 1432-0746. Dostupné z: https://doi.org/10.1051/0004-6361/201833098.

@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 = {https://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. \textit{ASTRONOMY \&{} ASTROPHYSICS}. Les Ulis: EDP SCIENCES S A, 2019, roč.~622, JAN 30 2019, s.~77-82. ISSN~1432-0746. Dostupné z: https://doi.org/10.1051/0004-6361/201833098.

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