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The Astrophysical Journal (ApJ)

Resumen/Descripción – provisto por la editorial en inglés

The Astrophysical Journal is an open access journal devoted to recent developments, discoveries, and theories in astronomy and astrophysics. Publications in ApJ constitute significant new research that is directly relevant to astrophysical applications, whether based on observational results or on theoretical insights or modeling.

Palabras clave – provistas por la editorial

astronomy; astrophysics

Disponibilidad

Institución detectada	Período	Navegá	Descargá	Solicitá
No detectada	desde jul. 1995 / hasta dic. 2023	IOPScience

Información

Tipo de recurso:

revistas

ISSN impreso

0004-637X

ISSN electrónico

1538-4357

Editor responsable

American Astronomical Society (AAS)

Idiomas de la publicación

inglés

País de edición

Reino Unido

Información sobre licencias CC

https://creativecommons.org/licenses/by/4.0/

Cobertura temática

Ciencias físicas

Tabla de contenidos

doi: 10.3847/1538-4357/ab3924

Envelope Convection, Surface Magnetism, and Spots in A and Late B-type Stars

Matteo Cantiello; Jonathan Braithwaite

<jats:title>Abstract</jats:title> <jats:p>Weak magnetic fields have recently been detected in a number of A-type stars, including Vega and Sirius. At the same time, space photometry observations of A and late B-type stars from <jats:italic>Kepler</jats:italic> and <jats:italic>TESS</jats:italic> have highlighted the existence of rotational modulation of surface features akin to stellar spots. Here we explore the possibility that surface magnetic spots might be caused by the presence of small envelope convective layers at or just below the stellar surface, caused by recombination of H and He. Using 1D stellar evolution calculations and assuming an equipartition dynamo, we make simple estimates of field strength at the photosphere. For most models, the largest effects are caused by a convective layer driven by second helium ionization. While it is difficult to predict the geometry of the magnetic field, we conclude that the majority of intermediate-mass stars should have dynamo-generated magnetic fields of order a few Gauss at the surface. These magnetic fields can appear at the surface as bright spots and cause photometric variability via rotational modulation, which could also be widespread in A-stars. The amplitude of surface magnetic fields and their associated photometric variability are expected to decrease with increasing stellar mass and surface temperature, so that magnetic spots and their observational effects should be much harder to detect in late B-type stars.</jats:p>