|
Título:
|
XMM-Newton monitoring of the close pre-main-sequence binary AK Sco. Evidence of tide-driven filling of the inner gap in the circumbinary disk
|
|
Autores:
|
Gómez de Castro, Ana Inés ;
López Santiago, Javier ;
Talavera, A. ;
Sytov, A. Y. ;
Bisikalo, D.
|
|
Tipo de documento:
|
texto impreso
|
|
Editorial:
|
IOP Publishing, 2013-03
|
|
Dimensiones:
|
application/pdf
|
|
Nota general:
|
info:eu-repo/semantics/openAccess
|
|
Idiomas:
|
|
|
Palabras clave:
|
Estado = Publicado
,
Materia = Ciencias: Matemáticas: Astronomía
,
Tipo = Artículo
|
|
Resumen:
|
AK Sco stands out among pre-main-sequence binaries because of its prominent ultraviolet excess, the high eccentricity of its orbit, and the strong tides driven by it. AK Sco consists of two F5-type stars that get as close as 11 R-* at periastron passage. The presence of a dense (n(e) similar to 10(11) cm(-3)) extended envelope has been unveiled recently. In this article, we report the results from an XMM-Newton-based monitoring of the system. We show that at periastron, X-ray and UV fluxes are enhanced by a factor of similar to 3 with respect to the apastron values. The X-ray radiation is produced in an optically thin plasma with T similar to 6.4 x 10(6) K and it is found that the N-H column density rises from 0.35 x 10(21) cm(-2) at periastron to 1.11 x 10(21) cm(-2) at apastron, in good agreement with previous polarimetric observations. The UV emission detected in the Optical Monitor band seems to be caused by the reprocessing of the high-energy magnetospheric radiation on the circumstellar material. Further evidence of the strong magnetospheric disturbances is provided by the detection of line broadening of 278.7 km s(-1) in the Nv line with Hubble Space Telescope/Space Telescope Imaging Spectrograph. Numerical simulations of the mass flow from the circumbinary disk to the components have been carried out. They provide a consistent scenario with which to interpret AK Sco observations. We show that the eccentric orbit acts like a gravitational piston. At apastron, matter is dragged efficiently from the inner disk border, filling the inner gap and producing accretion streams that end as ring-like structures around each component of the system. At periastron, the ring-like structures come into contact, leading to angular momentum loss, and thus producing an accretion outburst.
|
|
En línea:
|
https://eprints.ucm.es/id/eprint/21229/1/castro100oficial.pdf
|
