Bibcode
DOI
Díaz-Santos, T.; Alonso-Herrero, A.; Colina, L.; Ryder, S. D.; Knapen, J. H.
Referencia bibliográfica
The Astrophysical Journal, Volume 661, Issue 1, pp. 149-164.
Fecha de publicación:
5
2007
Revista
Número de citas
60
Número de citas referidas
55
Descripción
We investigate the stellar populations in the star-forming ring of the
luminous infrared galaxy NGC 7469. We use HST multiwavelength (UV
through NIR) imaging complemented with new K-band ground-based long-slit
spectroscopy, and mid-IR and radio maps from the literature. SEDs and
evolutionary synthesis models have been used to characterize the star
formation at different scales, from those of individual star clusters
(tens of pc) to that of the entire star-forming ring (kpc scale). At the
smallest scales two different populations of massive
(1-10×106 Msolar) clusters are identified.
About 25% of the clusters are young (1-3 Myr) and extincted
(AV~3 mag), whereas the vast majority are of intermediate age
(~9-20 Myr) and less obscured (AV~1 mag). At larger (hundreds
of pc) scale, an analysis of the integrated SED and spectroscopic data
of the ring indicates the presence of two stellar populations. The young
(5-6 Myr) and obscured stellar population accounts for the Brγ
emission and most of the IR luminosity, and for about one-third of the
stellar mass of the ring. The much less obscured intermediate-age
population has properties similar to those of the majority of the
(older) 1.1 μm-selected star clusters. The distribution of these two
populations is clearly different and even spatially anticorrelated. The
UV-optical-NIR continuum (including the majority of the clusters) of the
ring traces mostly the mildly obscured intermediate-age population,
while the MIR and radio peaks mark the location of the youngest and
obscured star-forming regions. Moreover, the two brightest MIR and radio
peaks are spatially coincident with the ends of the nuclear molecular
gas bar. This study emphasizes the need for multiwavelength, high
angular resolution observations to characterize the star formation in
the dust-obscured regions commonly present in LIRGs.