124 research outputs found
Faint dwarf galaxies in the Next Generation Virgo cluster Survey
The Next Generation Virgo Cluster Survey (NGVS) is a CFHT Large Program that
is using the wide field of view capabilities of the MegaCam camera to map the
entire Virgo Cluster from its core to virial radius. The observing strategy has
been optimized to detect very low surface brightness structures in the cluster,
including intracluster stellar streams and faint dwarf spheroidal galaxies. We
present here the current status of this ongoing survey, with an emphasis on the
detection and analysis of the very low-mass galaxies in the cluster that have
been revealed by the NGVS.Comment: 6 pages, 2 figures, Conference Proceedings: "A Universe of Dwarf
Galaxies", 14-18 June 2010, Lyon, Franc
Galaxies at the extremes: Ultra-diffuse galaxies in the Virgo Cluster
We report the discovery of three large (R29 >~ 1 arcminute) extremely low
surface brightness (mu_(V,0) ~ 27.0) galaxies identified using our deep,
wide-field imaging of the Virgo Cluster from the Burrell Schmidt telescope.
Complementary data from the Next Generation Virgo Cluster Survey do not resolve
red giant branch stars in these objects down to i=24, yielding a lower distance
limit of 2.5 Mpc. At the Virgo distance, these objects have half-light radii
3-10 kpc and luminosities L_V=2-9x10^7 Lsun. These galaxies are comparable in
size but lower in surface brightness than the large ultradiffuse LSB galaxies
recently identified in the Coma cluster, and are located well within Virgo's
virial radius; two are projected directly on the cluster core. One object
appears to be a nucleated LSB in the process of being tidally stripped to form
a new Virgo ultracompact dwarf galaxy. The others show no sign of tidal
disruption, despite the fact that such objects should be most vulnerable to
tidal destruction in the cluster environment. The relative proximity of Virgo
makes these objects amenable to detailed studies of their structural properties
and stellar populations. They thus provide an important new window onto the
connection between cluster environment and galaxy evolution at the extremes.Comment: 7 pages, 4 figures, to appear in ApJ Letters. Updated with minor
revisions to match accepted versio
Galaxies at the extremes: Ultra-diffuse galaxies in the Virgo Cluster
We report the discovery of three large (R29 >~ 1 arcminute) extremely low
surface brightness (mu_(V,0) ~ 27.0) galaxies identified using our deep,
wide-field imaging of the Virgo Cluster from the Burrell Schmidt telescope.
Complementary data from the Next Generation Virgo Cluster Survey do not resolve
red giant branch stars in these objects down to i=24, yielding a lower distance
limit of 2.5 Mpc. At the Virgo distance, these objects have half-light radii
3-10 kpc and luminosities L_V=2-9x10^7 Lsun. These galaxies are comparable in
size but lower in surface brightness than the large ultradiffuse LSB galaxies
recently identified in the Coma cluster, and are located well within Virgo's
virial radius; two are projected directly on the cluster core. One object
appears to be a nucleated LSB in the process of being tidally stripped to form
a new Virgo ultracompact dwarf galaxy. The others show no sign of tidal
disruption, despite the fact that such objects should be most vulnerable to
tidal destruction in the cluster environment. The relative proximity of Virgo
makes these objects amenable to detailed studies of their structural properties
and stellar populations. They thus provide an important new window onto the
connection between cluster environment and galaxy evolution at the extremes.Comment: 7 pages, 4 figures, to appear in ApJ Letters. Updated with minor
revisions to match accepted versio
A Tale of Two Tails: Exploring Stellar Populations in the Tidal Tails of NGC 3256
We have developed an observing program using deep, multiband imaging to probe
the chaotic regions of tidal tails in search of an underlying stellar
population, using NGC 3256's 400 Myr twin tidal tails as a case study. These
tails have different colours of and for NGC 3256W, and and
for NGC 3256E, indicating different stellar populations. These colours
correspond to simple stellar population ages of Myr and
Myr for NGC 3256W and NGC 3256E, respectively, suggesting
NGC 3256W's diffuse light is dominated by stars formed after the interaction,
while light in NGC 3256E is primarily from stars that originated in the host
galaxy. Using a mixed stellar population model, we break our diffuse light into
two populations: one at 10 Gyr, representing stars pulled from the host
galaxies, and a younger component, whose age is determined by fitting the model
to the data. We find similar ages for the young populations of both tails,
( and Myr for NGC 3256W and NGC 3256E,
respectively), but a larger percentage of mass in the 10 Gyr population for NGC
3256E ( vs ). Additionally, we detect 31 star
cluster candidates in NGC 3256W and 19 in NGC 2356E, with median ages of 141
Myr and 91 Myr, respectively. NGC 3256E contains several young (< 10 Myr), low
mass objects with strong nebular emission, indicating a small, recent burst of
star formation.Comment: Accepted for publication in MNRAS. 16 pages, 19 figure
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