Aparicio, A.; Hidalgo, S. L.; Buonanno, R.; Fusco, F.; Pietrinferni, A.; Bono, G.; Monelli, M.; Cassisi, S.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 572, id.A26, 9 pp.
Fecha de publicación:
12
2014
Revista
Número de citas
10
Número de citas referidas
9
Descripción
We present a detailed photometric study of the dwarf irregular galaxy
NGC 6822 aimed at investigating the properties of its stellar
populations and, in particular, the presence of stellar radial
gradients. Our goal is to analyse the stellar populations in six fields,
which cover the whole bar of this dwarf galaxy. We derived the
quantitative star formation history (SFH) of the six fields using the
IAC method, involving IAC-pop/MinnIAC codes. The solutions we derived
show an enhanced star formation rate (SFR) in Fields 1 and 3 during the
past 500 Myr. The SFRs of the other fields are almost extinguished at
very recent epochs and. We study the radial gradients of the SFR and
consider the total mass converted into stars in two time intervals
(between 0 and 0.5 Gyr ago and between 0.5 and 13.5 Gyr ago). We find
that the scale lengths of the young and intermediate-to-old populations
are perfectly compatible, with the exception of the young populations in
Fields 1 and 3. The recent SF in these two fields is greater than in the
other ones. This might be an indication that in these two fields we are
sampling incipient spiral arms. Further evidence and new observations
are required to prove this hypothesis. In addition, we derived the
age-metallicity relations. As expected, the metallicity increases with
time for all of the fields. We do not observe any radial gradient in the
metallicity.
Based on observations collected with the ACS on board the NASA/ESA
HST.The photometric catalogue is only available at the CDS via anonymous
ftp to http://cdsarc.u-strasbg.fr
(ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/572/A26
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