HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4730
PERIOD COVERED: 5am November 3 - 5am November 4, 2008 (DOY
308/1000z-309/1000z)
OBSERVATIONS SCHEDULED
ACS/SBC 11151
Evaluating the Role of Photoevaporation of Protoplanetary
Disk Dispersal
Emission produced by accretion onto the central star leads
to
photoevaporation, which may play a fundamental role in
disk dispersal.
Models of disk photoevaporation by the central star are
challenged by
two potential problems: the emission produced by accretion
will be
substantially weaker for low-mass stars, and photoevaporation
must
continue as accretion slows. Existing FUV spectra of CTTSs
are biased to
solar-mass stars with high accretion rates, and are
therefore
insufficient to address these problems. We propose use
HST/ACS SBC
PR130L to obtain FUV spectra of WTTSs and of CTTSs at low
masses and
mass accretion rates to provide crucial data to evaluate
photoevaporation models. We will estimate the FUV and EUV
luminosities
of low-mass CTTSs with small mass accretion rates, CTTSs
with transition
disks and slowed accretion, and of magnetically-active
WTTSs.
ACS/SBC 11681
A Search for Ultraviolet Emission Filaments in Cool Core
Clusters
We propose to use ACS SBC imaging to seek ultraviolet CIV
emission
filaments in clusters of galaxies exhibiting strong
cool-core X-ray
emission and optical line emission filaments. These short
observations
are crafted to test thermal conduction models for the
filament
excitation, and can significantly impact our understanding
of the
overall physical processes dominant in the galaxy cluster
ISM.
FGS 11212
Filling the Period Gap for Massive Binaries
The current census of binaries among the massive O-type
stars is
seriously incomplete for systems in the period range from
years to
millennia because the radial velocity variations are too
small and the
angular separations too close for easy detection. Here we
propose to
discover binaries in this observational gap through a
Faint Guidance
Sensor SNAP survey of relatively bright targets listed in
the Galactic O
Star Catalog. Our primary goal is to determine the binary
frequency
among those in the cluster/association, field, and runaway
groups. The
results will help us assess the role of binaries in
massive star
formation and in the processes that lead to the ejection
of massive
stars from their natal clusters. The program will also
lead to the
identification of new, close binaries that will be targets
of long term
spectroscopic and high angular resolution observations to
determine
their masses and distances. The results will also be
important for the
interpretation of the spectra of suspected and newly
identified binary
and multiple systems.
WFPC2 11196
An Ultraviolet Survey of Luminous Infrared Galaxies in the
Local
Universe
At luminosities above 10^11.4 L_sun, the space density of
far-infrared
selected galaxies exceeds that of optically selected
galaxies. These
Luminous Infrared Galaxies {LIRGs} are primarily
interacting or merging
disk galaxies undergoing starbursts and creating/fueling
central AGN. We
propose far {ACS/SBC/F140LP} and near {WFPC2/PC/F218W} UV
imaging of a
sample of 27 galaxies drawn from the complete IRAS Revised
Bright Galaxy
Sample {RBGS} LIRGs sample and known, from our Cycle 14 B
and I-band ACS
imaging observations, to have significant numbers of
bright {23 < B < 21
mag} star clusters in the central 30 arcsec. The HST UV
data will be
combined with previously obtained HST, Spitzer, and GALEX
images to {i}
calculate the ages of the clusters as function of merger
stage, {ii}
measure the amount of UV light in massive star clusters
relative to
diffuse regions of star formation, {iii} assess the
feasibility of using
the UV slope to predict the far-IR luminosity {and thus
the star
formation rate} both among and within IR-luminous
galaxies, and {iv}
provide a much needed catalog of rest- frame UV
morphologies for
comparison with rest-frame UV images of high-z LIRGs and
Lyman Break
Galaxies. These observations will achieve the resolution
required to
perform both detailed photometry of compact structures and
spatial
correlations between UV and redder wavelengths for a
physical
interpretation our IRX-Beta results. The HST UV data,
combined with the
HST ACS, Spitzer, Chandra, and GALEX observations of this
sample, will
result in the most comprehensive study of luminous
starburst galaxies to
date.
WFPC2 11113
Binaries in the Kuiper Belt: Probes of Solar System
Formation and
Evolution
The discovery of binaries in the Kuiper Belt and related
small body
populations is powering a revolutionary step forward in
the study of
this remote region. Three quarters of the known binaries
in the Kuiper
Belt have been discovered with HST, most by our snapshot
surveys. The
statistics derived from this work are beginning to yield
surprising and
unexpected results. We have found a strong concentration
of binaries
among low-inclination Classicals, a possible size cutoff
to binaries
among the Centaurs, an apparent preference for nearly
equal mass
binaries, and a strong increase in the number of binaries
at small
separations. We propose to continue this successful
program in Cycle 16;
we expect to discover at least 13 new binary systems,
targeted to
subgroups where these discoveries can have the greatest
impact.
WFPC2 11218
Snapshot Survey for Planetary Nebulae in Globular Clusters
of the Local
Group
Planetary nebulae {PNe} in globular clusters {GCs} raise a
number of
interesting issues related to stellar and galactic
evolution. The number
of PNe known in Milky Way GCs, 4, is surprisingly low if one
assumes
that all stars pass through a PN stage. However, it is
likely that the
remnants of stars now evolving in Galactic GCs leave the
AGB so slowly
that any ejected nebula dissipates long before the star
becomes hot
enough to ionize it. Thus there should not be ANY PNe in
Milky Way
GCs--but there are four! It has been suggested that these
PNe are the
result of mergers of binary stars within GCs, i.e., that
they are
descendants of blue stragglers. The frequency of
occurrence of PNe in
external galaxies poses more questions, because it shows a
range of
almost an order of magnitude. I propose a Snapshot survey
aimed at
discovering PNe in the GC systems of Local Group galaxies
more distant
than the Magellanic Clouds. These clusters, some of which
may be much
younger than their counterparts in the Milky Way, might
contain many
more PNe than those of our own galaxy. I will use the
standard technique
of emission-line and continuum imaging, which easily
discloses PNe.
WFPC2 11302
WFPC2 CYCLE 16 Standard Darks - Part III
This dark calibration program obtains dark frames every
week in order to
provide data for the ongoing calibration of the CCD dark
current rate,
and to monitor and characterize the evolution of hot
pixels. Over an
extended period these data will also provide a monitor of
radiation
damage to the CCDs.
WFPC2 11793
WFPC2 Cycle 16 Internal Monitor
This calibration proposal is the Cycle 15 routine internal
monitor for
WFPC2, to be run weekly to monitor the health of the
cameras. A variety
of internal exposures are obtained in order to provide a
monitor of the
integrity of the CCD camera electronics in both bays (both
gain 7 and
gain 15 -- to test stability of gains and bias levels), a
test for
quantum efficiency in the CCDs, and a monitor for possible
buildup of
contaminants on the CCD windows. These also provide raw
data for
generating annual super-bias reference files for the
calibration
pipeline.
WFPC2 11795
WFPC2 Cycle 16 UV Earth Flats
Monitor flat field stability. This proposal obtains
sequences of earth
streak flats to improve the quality of pipeline flat
fields for the
WFPC2 UV filter set. These Earth flats will complement the
UV earth flat
data obtained during cycles 8-15.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS: (None)
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
12
12
FGS REacq
02
02
OBAD with Maneuver
28
28
SIGNIFICANT EVENTS: (None)