Stellar dynamics of blue compact galaxies. II. Further indications of a merger in ESO 338-IG04
Artikel i vetenskaplig tidskrift, 2008

Context: Luminous blue compact galaxies, common at ∼ 1 but now relatively rare, show disturbed kinematics in emission lines. Aims: As part of a programme to understand their formation and evolution, we have investigated the stellar dynamics of a number of nearby objects in this class. Methods: We obtained long-slit spectra with VLT/FORS2 in the spectral region covering the near-infrared calcium triplet. In this paper we focus on the well-known luminous blue compact galaxy ESO 338-IG04(Tololo 1924-416). A previous investigation, using Fabry-Perot interferometry, showed that this galaxy has a chaotic Hαvelocity field, indicating that either the galaxy is not in dynamical equilibrium or that Hαdoes not trace the gravitational potential due to feedback from star formation. Results: Along the apparent major axis, the stellar and ionised gas velocities for the most part follow each other. The chaotic velocity field must therefore be a sign that the young stellar population in ESO 338-IG04is not in dynamical equilibrium. The most likely explanation, which is also supported by its morphology, is that the galaxy has experienced a merger and that this has triggered the current starburst. Summarising the results of our programme so far, we note that emission-line velocity fields are not always reliable tracers of stellar motions, and go on to assess the implications for kinematic studies of similar galaxies at intermediate redshift. © 2008 ESO.

Galaxies: evolution

Galaxies: starburst

Galaxies: individual: ESO 338-IG04

Galaxies: kinematics and dynamics

Galaxies: interactions


Robert Cumming

Chalmers, Institutionen för radio- och rymdvetenskap

K. Fathi

G. Östlin

T. Marquart

I. Márquez

J. Másegosa

N. Bergvall

P. Amram

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 479 3 725-733


Astronomi, astrofysik och kosmologi


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