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Star-gas decoupling and a non-rotating stellar core in He 2-10.: Integral field spectroscopy with FLAMES/ARGUS
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
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2007 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, Vol. 474, no 1, 9-12 p.Article in journal (Refereed) Published
Abstract [en]

Aims: We study the two-dimensional distribution and kinematics of the stellar and gaseous components in the centre of the blue compact dwarf galaxy He 2-10. The aim is to compare the kinematics of gas and stars in order to determine whether they are consistent with one another, or if stars and gas can be decoupled due to gravitational perturbations and feedback from star formation. Methods: We have used the integral field unit ARGUS, part of FLAMES on the European Southern Observatory's Very Large Telescope, to target the Ca ii λλ8498,8542,8662 Å triplet in the central 300 × 480 parsecs of He 2-10. The selected wavelength regime includes several prominent spectral features, including the Paschen series and the [S iii] emission-line, which we have used to derive the kinematics of the ionised interstellar medium. Results: We find no systematic trend in the velocities of the stars over the observed field of view and conclude that the stellar kinematics is governed by random motions. This is in contrast to the motions the ionised interstellar medium, where we find spatial velocity variations up to 60 km s-1. Our gas velocity field is consistent with previous studies of both the molecular gas and the feedback-driven outflow in He 2-10. We interpret the kinematic decoupling between the stars and the gas as He 2-10 being in the process of transformation to a dwarf elliptical galaxy.

Place, publisher, year, edition, pages
2007. Vol. 474, no 1, 9-12 p.
Keyword [en]
galaxies: dwarf, galaxies: kinematics and dynamics, galaxies: starburst, galaxies: individual: He 2-10
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-14414DOI: 10.1051/0004-6361:20078142OAI: oai:DiVA.org:uu-14414DiVA: diva2:42184
Available from: 2008-01-30 Created: 2008-01-30 Last updated: 2013-01-23Bibliographically approved
In thesis
1. Star-forming Dwarf Galaxies: Internal motions and evolution
Open this publication in new window or tab >>Star-forming Dwarf Galaxies: Internal motions and evolution
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The study of dwarf galaxies is important in order to better understand the physics of the young universe and how larger galaxies form and evolve. In this work we focus on Blue Compact Galaxies (BCGs) which havemuch enhanced star formation (starbursts), causing blue colours and strong emission line spectra.

Investigating of the inner motions of BCGs provides a means for determining masses and understanding what triggered the current starburst. We have used the Very Large Telescope to perform challenging observations of the stellar motions in several BCGs, as seen in the near-infrared Ca-triplet absorption lines. By comparing these to the kinematics of the ionized interstellar medium, we were able to look into the role of feeback from stellar winds and supernova explosions, as well as further strengthen the notion that the merging of galaxies plays an important role.

Spatially resolved spectroscopy can yield information about the 3D-structure of galaxies. We have used a Fabry-Perot interferometer to study the kinematics of the interstellar medium in two samples of galaxies, each containing about twenty objects. We find strong indications for ongoing galaxy mergers that correlate well with the strength of the star-formation activity. Furthermore, by estimating dynamical masses, BCGs are shown to be on average not dynamically supported by rotation.

In addition, we have used data from the Sloan Digital Sky Survey to study the frequency of starbursts in the local universe and the connection to their descendants. We selected starbursts by the strength of emission in H-alpha, the first Balmer recombination line, and post-starbursts by the strength of absorption in H-delta. These are indicators of currently ongoing and recent, on the order of 100 Myr, star-formation, respectively. By modelling the stellar populations we derive ages and masses and can establish a link between starbursts and postbursts in a time sequence. We find that starbursts are active on a 100 Myr timescale but are rare objects in the local universe.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 27 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 977
Galaxy, Galaxies, Dynamics, Kinematics, Starburst, Dwarf Galaxies, Blue Compact Galaxies, Star Formation, Galaxy mergers, 3D-Spectroscopy, Spectroscopy
National Category
Astronomy, Astrophysics and Cosmology
Research subject
urn:nbn:se:uu:diva-181481 (URN)978-91-554-8483-5 (ISBN)
Public defence
2012-11-12, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Available from: 2012-10-19 Created: 2012-09-24 Last updated: 2013-01-23Bibliographically approved

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Publisher's full texthttp://adsabs.harvard.edu/abs/2007A%26A...474L...9M

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