17 research outputs found
Past and present star formation in the SMC: NGC 346 and its neighborhood
In the quest of understanding how star formation occurs and propagates in the
low metallicity environment of the Small Magellanic Cloud (SMC), we acquired
deep F555W (~V), and F814W (~I) HST/ACS images of the young and massive star
forming region NGC 346. These images and their photometric analysis provide us
with a snapshot of the star formation history of the region. We find evidence
for star formation extending from ~10 Gyr in the past until ~150 Myr in the
field of the SMC. The youngest stellar population (~3 +/- 1 Myr) is associated
with the NGC 346 cluster. It includes a rich component of low mass pre-main
sequence stars mainly concentrated in a number of sub-clusters, spatially co-
located with CO clumps previously detected by Rubio et al. (2000). Within our
analysis uncertainties, these sub-clusters appear coeval with each other. The
most massive stars appear concentrated in the central sub-clusters, indicating
possible mass segregation. A number of embedded clusters are also observed.
This finding, combined with the overall wealth of dust and gas, could imply
that star formation is still active. An intermediate age star cluster, BS90,
formed ~4.3 +/-0.1 Gyr ago, is also present in the region. Thus, this region of
the SMC has supported star formation with varying levels of intensity over much
of the cosmic time.Comment: 38 pages, 13 figures, 3 tables; AJ accepte
Intergalactic HII Regions Discovered in SINGG
A number of very small isolated HII regions have been discovered at projected
distances up to 30 kpc from their nearest galaxy. These HII regions appear as
tiny emission line objects in narrow band images obtained by the NOAO Survey
for Ionization in Neutral Gas Galaxies (SINGG). We present spectroscopic
confirmation of four isolated HII regions in two systems, both systems have
tidal HI features. The results are consistent with stars forming in interactive
debris due to cloud-cloud collisions. The H-alpha luminosities of the isolated
HII regions are equivalent to the ionizing flux of only a few O stars each.
They are most likely ionized by stars formed in situ, and represent atypical
star formation in the low density environment of the outer parts of galaxies. A
small but finite intergalactic star formation rate will enrich and ionize the
surrounding medium. In one system, NGC 1533, we calculate a star formation rate
of 1.5e-3 msun/yr, resulting in a metal enrichment of ~1e-3 solar for the
continuous formation of stars. Such systems may have been more common in the
past and a similar enrichment level is measured for the `metallicity floor' in
damped Lyman-alpha absorption systems.Comment: accepted for publication in the Astronomical Journal, 19 pages,
including 5 figures, some low resolution. Paper with high resolution images
can be downloaded from
http://astro.ph.unimelb.edu.au/~eryan/publications/eldots.ps.g
Higher education in Indonesia: Contemporary challenges in governance, access, and quality
This chapter presents the development of Indonesian higher education since its origins to current
challenges in the fields of governance, autonomy, access, equity, quality, and
internationalization. Indonesia has a massive and diversified tertiary education, including
experiments in community colleges and online programs. The higher educational system remains
mainly centralized, with the exception of some reforms towards financial autonomy. Insufficient
public funding hinders the capacity to provide adequate teaching, research, and facilities among
other aspects. The consequential rise in student fees contributes to an overrepresentation of
students from Java, urban centers, and higher social classes