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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 225801.0, MPI für Astronomie / Publikationen_mpia
The stellar content and star formation history
of the late-type spiral galaxy NGC 300 from
Hubble Space Telescope observations
Authors:Butler, D. J.; Martínez-Delgado, D.; Brandner, W.
Date of Publication (YYYY-MM-DD):2004
Title of Journal:The Astronomical Journal
Start Page:1472
End Page:1485
Review Status:not specified
Audience:Not Specified
Abstract / Description:We present the first Hubble Space Telescope
(HST) WFPC2 V and I photometry for the Sculptor
Group galaxy NGC 300 in four fields ranging from
the center to the outer edge. We have made the
first measurement of the star formation
histories in two disk fields: the oldest stars
were born at similar epochs and formation
activity increased but at different mean rates.
The main disk stellar population is predominantly
old, consisting of red giant branch (RGB) and
asymptotic giant branch (AGB) stars, based on a
synthetic color-magnitude diagram analysis. The
metallicity Z is found to have been less than
0.006 (or 0.33 Zsolar), with no
evidence for significant change in mean Z over
time in both disk fields. In the central region,
we find a dearth of bright stars with respect to
the two disk fields that cannot be explained by
observational effects. Taken at face value, this
finding would agree with the Davidge report of
suppressed star formation there during the past
109 yr with respect to his disk fields
at larger radii; but the possibility remains
that significant central extinction affects our
finding. We have also determined the first
distance modulus estimate based on the tip of the
red giant branch method. On the Cepheid distance
scale of Ferrarese et al., we find
(m-M)0=26.56+/-0.07(+/-0.13) mag and a
similar value from the Cepheid-independent
empirical method of Lee, Freedman, ‚‚amp; Madore,
both in good agreement with the Cepheid distance
determined by Freedman et al. A discrepancy
between this value and the theoretical
calibration of the red giant branch tip
magnitude method remains. Finally, we report a
newly detected young (up to about 10 Myr) stellar
association of about average size (~140 pc) in
one of the disk fields.
Free Keywords:Galaxies: Distances and Redshifts; Galaxies:
; Formation; Galaxies: General; Galaxies: Spiral;
; Stars: Formation
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
External Affiliations:K‚‚ouml;nigstuhl 17, D-69117 Heidelberg, Germany;
<EMAIL>butler@mpia.de, ddelgado@mpia.de,
brandner@mpia.de</EMAIL>), AB(Max-Planck-Institut
f‚‚uuml;r Astronomie, K‚‚ouml;nigstuhl 17,
D-69117 Heidelberg, Germany;
<EMAIL>butler@mpia.de, ddelgado@mpia.de,
brandner@mpia.de</EMAIL>), AC(Max-Planck-Institut
f‚‚uuml;r Astronomie, K‚‚ouml;nigstuhl 17,
D-69117 Heidelberg, Germany;
<EMAIL>butler@mpia.de, ddelgado@mpia.de,
Identifiers:URL:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bi... [ID No:1]
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