Bibcode
Fernández-Ontiveros, J. A.; Prieto, M. A.; Acosta-Pulido, J. A.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society: Letters, Volume 392, Issue 1, pp. L16-L20.
Advertised on:
1
2009
Citations
52
Refereed citations
49
Description
Very Large Telescope adaptive optics images of NGC 253 with resolutions
down to 200mas resolve the central 300pc of this galaxy in ~37 infrared
(IR) bright knots, a factor of 3 larger than previously reported and
extended diffuse emission. The angular resolution, comparable to that of
available Very Large Array 2cm maps, permits us a very accurate IR-radio
registration. Eight radio sources are found to have an IR counterpart.
The knots have Hα equivalent width of about 80Å, sizes of
~3pc, magnitudes in L band of about 12mag and relatively high
extinction, AV ~ 7mag. Their spectral energy distributions
(SEDs) look very similar, characterized by a maximum at 20μm and a
gentle bump in the 1-2μm range. These features can be well reproduced
by considering an important contribution of very young stellar objects
to the IR, efficiently heating their dust envelope. The evidence
indicates that these are young massive clusters bursting from their dust
cocoons. A median SED of the knots is provided, which may represent one
of the most genuine templates of an extragalactic circumnuclear
star-forming region. The lack of any optical or IR counterpart for the
previously identified radio core calls into question its supposed active
nucleus nature. This source may instead represent a scaled up version of
Sgr A* at the Galactic Centre.
Based on European Southern Observatory-Very Large Telescope programs
076.B-0493, 074.A-9016 and 076.B-0656 and Hubble Space Telescope
programs U43A0103B and U31Q0101B.
E-mail: jafo [at] iac.es (jafo[at]iac[dot]es)
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