Universität zu Köln

Zajacek, Michal ORCID: 0000-0001-6450-1187, Karas, Vladimir ORCID: 0000-0002-5760-0459 and Eckart, Andreas ORCID: 0000-0001-6049-3132 (2014). Dust-enshrouded star near supermassive black hole: predictions for high-eccentricity passages near low-luminosity galactic nuclei. Astron. Astrophys., 565. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. Supennassive black holes reside in cores of galaxies. where they are often surrounded by a nuclear cluster and a clumpy torus of gas and dust. Mutual interactions can set some stars on a plunging trajectory towards the black hole. Aims. We model the pericentre passage of a dust-enshrouded star during which the dusty envelope becomes stretched by tidal forces and is affected by the interaction with the surrounding medium. In particular, we explore under which conditions these encounters can lead to periods of enhanced accretion activity. Methods. We discuss different scenarios for such a dusty source. To this end, we employed a modification of the Swift integration package. Elements of the cloud were modelled as numerical particles that represent the dust component that interacts with the optically thin gaseous environment. Results. We determine the fraction of the total mass of the dust component that is diverted from the original path during the passages through the pericentre at similar or equal to 10(3) Schwarzschild radii and find that the main part of the dust (greater than or similar to 90% of its mass) is significantly affected upon the first crossing. The fraction of mass captured at the second passage generally decreases to very low values. Conclusions. As an example, we show predictions for the dusty source evolution assuming the current orbital parameters of the G2 cloud (also known as Dusty S-Cluster Object, DSO) in our Galactic centre. Encounter of a core-less cloud with a supermassive black hole is, most likely, a non-repeating event: the cloud is destroyed. However, in the case of a dust-enshrouded star, part of the envelope survives the pericentre passage. We discuss an offset of less than or similar to 0.3 arcsec between the centre of mass of the diverted part and the star along the eccentric orbit. Finally, we examine an interesting possibility of a binary star embedded within a common wind envelope that becomes dispersed at the pericentre passage.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Zajacek, Michal UNSPECIFIED orcid.org/0000-0001-6450-1187 UNSPECIFIED Karas, Vladimir UNSPECIFIED orcid.org/0000-0002-5760-0459 UNSPECIFIED Eckart, Andreas UNSPECIFIED orcid.org/0000-0001-6049-3132 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-438791
DOI:	10.1051/0004-6361/201322713
Journal or Publication Title:	Astron. Astrophys.
Volume:	565
Date:	2014
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute of Physics I
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SAGITTARIUS-A-ASTERISK; GAS CLOUD G2; PROPER MOTIONS; BOW SHOCK; MASS STAR; S-STARS; ACCRETION; ORIGIN; WIND; HYPERVELOCITY Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/43879