EDP Sciences
Free Access
Issue
A&A
Volume 449, Number 3, April III 2006
Page(s) 997 - 1017
Section Extragalactic astronomy
DOI https://doi.org/10.1051/0004-6361:20053119
A&A 449, 997-1017 (2006)
DOI: 10.1051/0004-6361:20053119

Star formation and stellar populations in the Wolf-Rayet(?) luminous compact blue galaxy IRAS 08339+6517

Á. R. López-Sánchez, C. Esteban and J. García-Rojas

Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
    e-mail: angelrls@iac.es

(Received 23 March 2005 / Accepted 28 November 2005)

Abstract
Aims.IRAS 08339+6517 is a luminous infrared and Ly$\alpha$-emitting starburst galaxy that possesses a dwarf companion object at a projected distance of 56 kpc. An $\ion{H}{i}$ tidal tail has recently been detected between both galaxies, suggesting that about 70% of the neutral gas has been ejected from them.
Methods.We present deep broad-band optical images, together with narrow band H$\alpha$ CCD images, and optical intermediate-resolution spectroscopy of both galaxies.
Results.The images reveal interaction features between both systems and strong H$\alpha$ emission in the inner part of IRAS 08339+6517. The chemical composition of the ionized gas of the galaxies is rather similar. The analysis of their kinematics also indicates interaction features and reveals an object that could be a candidate tidal dwarf galaxy or a remnant of an earlier merger. Our data suggest that the $\ion{H}{i}$ tail has been mainly formed from material stripped from the main galaxy. We find weak spectral features that could be attributed to the presence of Wolf-Rayet stars in this starburst galaxy and estimate an age of the most recent burst of around 4-6 Myr. A more evolved underlying stellar population, with a minimal age between 100-200 Myr, is also detected and fits an exponential intensity profile. A model which combines 85% young and 15% old populations can explain both the spectral energy distribution and the $\ion{H}{i}$ Balmer and $\ion{He}{i}$ absorption lines presented in our spectrum. The star formation rate of the galaxy is consistently derived using several calibrations, giving a value of ~9.5 $M_{\odot}$ yr-1.
Conclusions.IRAS 08339+6517 does satisfy the criteria of a luminous compact blue galaxy, rare objects in the local universe but common at high redshifts, being a very interesting target for detailed studies of galaxy evolution and formation.


Key words: galaxies: starburst -- galaxies: interactions -- galaxies: abundances -- galaxies: kinematics and dynamics -- stars: Wolf-Rayet

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© ESO 2006

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