Distribution of the high-velocity clouds in the Galactic halo

Context. There is a connection between the kinematics and sky distribution of the high velocity clouds (HVCs) and the spatial velocity and orbital plane of the Magellanic Clouds (MCs) that allow us to conclude that most HVCs were ejected from the Clouds, some hundreds of Myrs ago, probably by an enc...

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Detalles Bibliográficos
Autor principal: Olano, Carlos Alberto
Formato: Articulo
Lenguaje:Inglés
Publicado: 2008
Materias:
Ciencias Astronómicas
Galaxies: interactions
Galaxies: Magellanic Clouds
Galaxy: halo
ISM: clouds
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84248
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-84248
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Astronómicas
Galaxies: interactions
Galaxies: Magellanic Clouds
Galaxy: halo
ISM: clouds
spellingShingle Ciencias Astronómicas
Galaxies: interactions
Galaxies: Magellanic Clouds
Galaxy: halo
ISM: clouds
Olano, Carlos Alberto
Distribution of the high-velocity clouds in the Galactic halo
topic_facet Ciencias Astronómicas
Galaxies: interactions
Galaxies: Magellanic Clouds
Galaxy: halo
ISM: clouds
description Context. There is a connection between the kinematics and sky distribution of the high velocity clouds (HVCs) and the spatial velocity and orbital plane of the Magellanic Clouds (MCs) that allow us to conclude that most HVCs were ejected from the Clouds, some hundreds of Myrs ago, probably by an encounter between the Large (LMC) and Small Magellanic Cloud (SMC). Aims. Based on the idea that HVCs have progenitors in the MCs, we attempt determine theoretical distances to the HVCs using observed data of the sky positions and radial velocities, and thus to map the spatial distribution of the HVCs. Methods. i) In the context of a kinematical model we have found an analytical formula that gives the distance of an HVC; ii) we have developed two dynamical models in order to study the orbits of the HVCs under the gravitational forces exerted by the Galaxy and the MCs and forces of resistance due to the movement of the HVCs through the Galactic gaseous disk. We have adopted the gravitational potential of the Milky Way given by a dark matter halo (Model 1) plus a massive thick disk partially composed by dark matter (Model 2). By means of a fitting to certain Galactic, MC and HVC conditions we have obtained values for the free parameters of the Models. We have obtained the dynamical distances to the HVCs by constructing the theoretical relationship between the radial velocity and the distance in the line of sight of each HVC. Results. The HVCs can be divided into three major groups: Population MS, Population W and Population A-C. Population MS comprises the Magellanic stream and the leading arm of the Magellanic system. The HVCs of this population are dispersed around the MCs within a volume of ≈200 kpc × 200 kpc × 60 kpc. Population W is situated at a mean distance of ≈15 kpc from the Sun, and has been braked by the gas of the Galactic disk. Population A-C includes Complexes A, C, H, L, M, and ACHVC. The dynamical models give two solutions for the distance of each HVC of Population A-C. The near-distance solutions place Population A-C at ≈6 kpc from the Sun, showing that this chain of HVCs started to interact with the outer parts of the Galactic gaseous disk about 100 Myr ago. While, the spatial distribution of Population A-C represented with the far distances has the shape of a gigantic ring with a radius of ≈125 kpc. Our results support the idea that the LMC-SMC encounter triggered a period of star formation bursts, in which part of the LMC bar was probably formed. The interactions of a few 10<SUP>5</SUP> massive stars formed in this era with the then-existing low metallicity ISM of the MCs would have created the HVCs.
format Articulo
Articulo
author Olano, Carlos Alberto
author_facet Olano, Carlos Alberto
author_sort Olano, Carlos Alberto
title Distribution of the high-velocity clouds in the Galactic halo
title_short Distribution of the high-velocity clouds in the Galactic halo
title_full Distribution of the high-velocity clouds in the Galactic halo
title_fullStr Distribution of the high-velocity clouds in the Galactic halo
title_full_unstemmed Distribution of the high-velocity clouds in the Galactic halo
title_sort distribution of the high-velocity clouds in the galactic halo
publishDate 2008
url http://sedici.unlp.edu.ar/handle/10915/84248
work_keys_str_mv AT olanocarlosalberto distributionofthehighvelocitycloudsinthegalactichalo
bdutipo_str Repositorios
_version_ 1764820488527282176

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