Show simple item record

dc.contributor.authorCubarsí Morera, Rafael
dc.contributor.otherUniversitat Politècnica de Catalunya. Departament de Matemàtica Aplicada IV
dc.date.accessioned2015-07-01T08:38:01Z
dc.date.available2015-07-01T08:38:01Z
dc.date.created2014-05-27
dc.date.issued2014-05-27
dc.identifier.citationCubarsi, R. Conditions of consistency for multicomponent stellar systems. II. Is a point-axial symmetric model suitable for the Galaxy?. "Astronomy and astrophysics", 27 Maig 2014, vol. 567, p. 1-7.
dc.identifier.issn0004-6361
dc.identifier.urihttp://hdl.handle.net/2117/28482
dc.description.abstractUnder a common potential, a finite mixture of ellipsoidal velocity distributions satisfying the Boltzmann collisionless equation provides a set of integrability conditions that may constrain the population kinematics. They are referred to as conditions of consistency and were discussed in a previous paper on mixtures of axisymmetric populations. As a corollary, these conditions are now extended to point-axial symmetry, that is, point symmetry around the rotation axis or bisymmetry, by determining which potentials are connected with a more flexible superposition of stellar populations. Under point-axial symmetry, the potential is still axisymmetric, but the velocity and mass distributions are not necessarily. A point-axial stellar system is, in a natural way, consistent with a flat velocity distribution of a disc population. Therefore, no additional integrability conditions are required to solve the Boltzmann collisionless equation for such a population. For other populations, if the potential is additively separable in cylindrical coordinates, the populations are not kinematically constrained, although under point-axial symmetry, the potential is reduced to the harmonic function, which, for the Galaxy, is proven to be non-realistic. In contrast, a non-separable potential provides additional conditions of consistency. When mean velocities for the populations are unconstrained, the potential becomes quasi-stationary, being a particular case of the axisymmetric model. Then, the radial and vertical mean velocities of the populations can differ and produce an apparent vertex deviation of the whole velocity distribution. However, single population velocity ellipsoids still have no vertex deviation in the Galactic plane and no tilt in their intersection with a meridional Galactic plane. If the thick disc and halo ellipsoids actually have non-vanishing tilt, as the surveys of the solar neighbourhood that include RAdial Velocity Experiment (RAVE) data seem to show, the point-axial model is unable to fit the local velocity distribution. Conversely, the axisymmetric model is capable of making a better approach. If, in the end, more accurate data confirm a negligible tilt of the populations, then the point-axisymmetric model will be able to describe non-axisymmetric mass and velocity distributions, although in the Galactic plane the velocity distribution will still be axisymmetric.
dc.format.extent7 p.
dc.language.isoeng
dc.rightsAttribution-NonCommercial-NoDerivs 3.0 Spain
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/es/
dc.subjectÀrees temàtiques de la UPC::Matemàtiques i estadística::Matemàtica aplicada a les ciències
dc.subject.lcshKinematics
dc.subject.othergalaxies: kinematics and dynamics – Galaxy: solar neighbourhood – galaxies: statistics
dc.titleConditions of consistency for multicomponent stellar systems. II. Is a point-axial symmetric model suitable for the Galaxy?
dc.typeArticle
dc.subject.lemacCinemàtica
dc.contributor.groupUniversitat Politècnica de Catalunya. gAGE - Grup d'Astronomia i Geomàtica
dc.identifier.doi10.1051/0004-6361/201423813
dc.description.peerreviewedPeer Reviewed
dc.subject.amsClassificació AMS::70 Mechanics of particles and systems::70B Kinematics
dc.relation.publisherversionhttps://docs.google.com/viewer?url=http://www.aanda.org/articles/aa/pdf/forth/aa23813-14.pdf
dc.rights.accessOpen Access
local.identifier.drac14904242
dc.description.versionPostprint (published version)
local.citation.authorCubarsi, R.
local.citation.publicationNameAstronomy and astrophysics
local.citation.volume567
local.citation.startingPage1
local.citation.endingPage7


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record