Adiabatic evolution and capture into resonance: vertical heating of a growing stellar disc

Sridhar, S.; Touma, Jihad R.

Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/4863

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DC Field	Value	Language
dc.contributor.author	Sridhar, S.	-
dc.contributor.author	Touma, Jihad R.	-
dc.date.accessioned	2012-07-11T06:14:41Z	-
dc.date.available	2012-07-11T06:14:41Z	-
dc.date.issued	1996	-
dc.identifier.citation	Monthly Notices of the Royal Astronomical Society, 1996, Vol.279, p1263	en
dc.identifier.issn	0035-8711	-
dc.identifier.uri	http://hdl.handle.net/2289/4863	-
dc.description	Restricted Access	en
dc.description.abstract	When a resonant island sweeps through the phase space of a stellar system adiabatically, it could leave behind a radically altered distribution. Nearly all orbits will, generically, pass through resonance; some of them could be captured, dragged along, and released elsewhere in phase space. Building on earlier work in Solar system dynamics, we give a general formulation of the changes induced in a collisionless stellar system by the passage of a resonant island. We derive equations of evolution for coarse-grained distribution functions (DFs). These equations satisfy an H-theorem; thus the microscopic evolution is mixing, and effectively irreversible. We then present an application of the phenomenon of capture into resonance to the problem of vertically heating a slowly growing stellar disc, such as the one recently considered by Sridhar & Touma. We construct a simple model of the growth of a galactic disc in the symmetry plane of an oblate halo. The (2:2) resonance we study is between vertical and epicyclic oscillations about the (mainly) circular motions of stars. As the disc grows more massive, resonant stars rise high, levitating as it were, by converting their radial actions into vertical actions; they can reach several kpc above the plane, corresponding to vertical velocities > 60 km s(-1). Levitation is a possible mechanism for making the thick disc of our Galaxy. We end with a comparison of the results from the simple model with the more realistic orbital computations of Sridhar & Touma.	en
dc.language.iso	en	en
dc.publisher	Blackwell Publishing for the Royal Astronomical Society	en
dc.relation.uri	http://adsabs.harvard.edu/abs/1996MNRAS.279.1263S	en
dc.rights	1996 Blackwell Publishing for the Royal Astronomical Society	en
dc.title	Adiabatic evolution and capture into resonance: vertical heating of a growing stellar disc	en
dc.type	Article	en
Appears in Collections:	Research Papers (A&A)

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