INVESTIGADORES
HÄGELE Guillermo Federico
artículos
Título:
Implications of the kinematical structure of circumnuclear star-forming regions on their derived properties
Autor/es:
GUILLERMO F. HÄGELE, ÁNGELES I. DÍAZ, ROBERTO TERLEVICH, ELENA TERLEVICH, GUILLERMO L. BOSCH AND MÓNICA V. CARDACI
Revista:
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2013 vol. 432 p. 810 - 821
ISSN:
0035-8711
Resumen:
We review the results of high dispersion spectroscopy of 17circumnuclear
star-forming regions (CNSFRs) in 3 nearby early spiral galaxies,
NGC2903, NGC3310 and NGC3351. We find that single Gaussian
fitting to the Hbeta and [OIII]5007 line profiles results in velocity
dispersions around 32 km/s and 52km/s, respectively, while the IR CaII
triplet cross-correlation technique provides stellar velocity dispersion
values close to 50km/s.Even though multiple kinematical
components are present, the relation between gas velocity dispersion and
Balmer emission line luminosity (L-sigma relation) reproduces the
correlation for disk giant HII regions albeit with a larger scatter. The
scatter in the L-sigma relation is considerably reduced when
theoretical evolutionary corrections are applied suggesting that an age
range is present in the sample of CNSFRs.To analyse the observed
complex profiles, we performed multiple Gaussian component fits to
the Hbeta and [OIII]5007 lines obtaining optimal fits with two
Gaussians of diff erent width. These best fits indicate that the
narrower component has average velocity dispersion close to 23km/s while
the broader component shows average values in the range 50-60km/s for
both lines, close to the observed stellar velocity dispersions. The fl
uxes of the broad and narrow Hbeta components are similar. This is not
the case for [OII]5007 for which the broad components have higher fl
uxes than the narrow ones, thus producing a clear segregation in their
[Oiii]/H ratios.We suggest a possible scenario for
understanding the behaviour of CNSFRs in the L-sigma and
sigma_gas-sigma_star diagrams involving an inner gaseous disk
responsible for the narrow component of the emission lines.Our
main conclusion is that the presence of di fferent kinematical
components with similar total fluxes in the emission line spectrum of
CNSFRs raises important doubts regarding properties of the ionized gas
derived from global line ratios obtained with low resolution
spectroscopy in star-forming regions in the central regions of early
type galaxies. Given the ubiquity of these star-forming systems, ionized
gas analyses should be done preferably from high dispersion spectra
with high spatial resolution.