11 research outputs found
Star formation history in the SMC: the case of NGC602
Deep HST/ACS photometry of the young cluster NGC 602, located in the remote
low density "wing" of the Small Magellanic Cloud, reveals numerous pre-main
sequence stars as well as young stars on the main sequence. The resolved
stellar content thus provides a basis for studying the star formation history
into recent times and constraining several stellar population properties, such
as the present day mass function, the initial mass function and the binary
fraction. To better characterize the pre-main sequence population, we present a
new set of model stellar evolutionary tracks for this evolutionary phase with
metallicity appropriate for the Small Magellanic Cloud (Z = 0.004). We use a
stellar population synthesis code, which takes into account a full range of
stellar evolution phases to derive our best estimate for the star formation
history in the region by comparing observed and synthetic color-magnitude
diagrams. The derived present day mass function for NGC 602 is consistent with
that resulting from the synthetic diagrams. The star formation rate in the
region has increased with time on a scale of tens of Myr, reaching in the last 2.5 Myr, comparable to what is
found in Galactic OB associations. Star formation is most complete in the main
cluster but continues at moderate levels in the gas-rich periphery of the
nebula.Comment: 24 pages. Accepted for publication in A
Star formation in the small magellanic cloud: The youngest star clusters
AbstractWe recently launched a comprehensive ground based (ESO/VLT/NTT) and space (HST & SST) study of the present and past star formation in the Small Magellanic Cloud (SMC), in clusters and in the field, with the goal of understanding how star and cluster formation occur and propagate in an environment of low metallicity, with a gas and dust content that is significantly lower than in the Milky Way. In this paper, we present some preliminary results of the "young cluster" program, where we acquired deep F555W (~V), and F814W (~I) HST/ACS images of the four young and massive SMC star clusters: NGC 346, NGC 602, NGC 299, and NGC 376
The Spatial Distribution of Dust and Stellar Emission of the Magellanic Clouds
We study the emission by dust and stars in the Large and Small Magellanic
Clouds, a pair of low-metallicity nearby galaxies, as traced by their spatially
resolved spectral energy distributions (SEDs). This project combines Herschel
Space Observatory PACS and SPIRE far-infrared photometry with other data at
infrared and optical wavelengths. We build maps of dust and stellar luminosity
and mass of both Magellanic Clouds, and analyze the spatial distribution of
dust/stellar luminosity and mass ratios. These ratios vary considerably
throughout the galaxies, generally between the range and .
We observe that the dust/stellar ratios depend on the interstellar medium (ISM)
environment, such as the distance from currently or previously star-forming
regions, and on the intensity of the interstellar radiation field (ISRF). In
addition, we construct star formation rate (SFR) maps, and find that the SFR is
correlated with the dust/stellar luminosity and dust temperature in both
galaxies, demonstrating the relation between star formation, dust emission and
heating, though these correlations exhibit substantial scatter.Comment: 15 pages, 18 figures; ApJ, in press; version published in the journal
will have higher-resolution figure
A Panchromatic View OF NGC 602: Time-Resolved Star Formation with the Hubble and Spitzer Space Telescopes
We present the photometric catalogs for the star-forming cluster NGC 602 in
the wing of the Small Magellanic Cloud covering a range of wavelengths from
optical HST/ACS (F555W, F814W) and SMARTS/ANDICAM (V, I) to infrared
(Spitzer/IRAC 3.6, 4.5, 5.8, and 8 micron and MIPS 24 micron). Combining this
with IRSF (InfraRed Survey Facility) near-infrared photometry (J, H, Ks), we
compare the young main sequence (MS) and pre-main sequence (PMS) populations
prominent in the optical with the current young stellar object (YSO)
populations revealed by the infrared (IR). We analyze the MS and PMS population
with isochrones in color-magnitude diagrams to derive ages and masses. The
optical data reveal ~565 PMS candidates, low mass Stage III YSOs. We
characterize ~40 YSOs by fitting their spectral energy distributions (SEDs) to
a grid of models (Robitaille et al. 2007) to derive luminosities, masses and
evolutionary phase (Stage I-III). The higher resolution HST images reveal that
~70% of the YSO candidates are either multiples or protoclusters. For YSOs and
PMS sources found in common, we find a consistency in the masses derived. We
use the YSO mass function to derive a present-day star-formation rate of
~0.2-1.0 Msun/yr/kpc^2, similar to the rate derived from the optical star
formation history suggesting a constant star formation rate for this region. We
demonstrate a progression of star formation from the optical star cluster
center to the edge of the star forming dust cloud. We derive lifetimes of a few
10^5 years for the YSO Stages I and II.Comment: 55 pages, 18 Figures; High resolution images available form author
Accepted to Ap
Star formation history of the young cluster NGC602 in the Small Magellanic Cloud
Within the framework of a large coordinated HST effort to study the star formation processes and history of several fields in the SMC, we present the detailed history of the young cluster NGC602. In particular, we explore the characteristics of the many candidate pre main sequence (PMS) stars. We combine a new set of PMS stellar tracks for the metallicity Z = 0.004 with a stellar population synthesis model that takes into account all evolutionary phases. The best star formation is searched by comparing observed and synthetic CMDs