HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4514
PERIOD
COVERED: UT December 26, 2007 (DOY 360)
OBSERVATIONS
SCHEDULED
ACS/SBC
11145
Probing
the Planet Forming Region of T Tauri Stars in Chamaeleon
By studying
the inner, planet-forming regions of circumstellar disks
around
low-mass pre- main sequence stars we can refine theories of giant
planet
formation and develop timescales for the evolution of disks and
their
planets. Spitzer infrared observations of T Tauri stars in the
Chamaeleon
star-forming region have given us an unprecedented look at
dust
evolution in young objects. However, despite this ground breaking
progress
in studying the dust in young disks, the gas properties of the
inner
disk remain essentially unknown. Using ACS on HST, we propose to
measure
the H_2 emission originating in the innermost disk regions of
classical
T Tauri stars in different stages of evolution with the
objective
of revealing the timescales of gas dissipation and its
relationship
to dust evolution. This proposal is part of a comprehensive
effort
with approved programs on Spitzer, Gemini, and Magellan that aim
to
characterize the state of gas and dust in disks where planets may
already
have formed.
FGS
11210
The
Architecture of Exoplanetary Systems
Are
all planetary systems coplanar? Concordance cosmogony makes that
prediction.
It is, however, a prediction of extrasolar planetary system
architecture
as yet untested by direct observation for main sequence
stars
other than the Sun. To provide such a test, we propose to carry
out
FGS astrometric studies on four stars hosting seven companions. Our
understanding
of the planet formation process will grow as we match not
only
system architecture, but formed planet mass and true distance from
the
primary with host star characteristics for a wide variety of host
stars
and exoplanet masses. We propose that a series of FGS astrometric
observations
with demonstrated 1 millisecond of arc per- observation
precision
can establish the degree of coplanarity and component true
masses
for four extrasolar systems: HD 202206 {brown dwarf+planet}; HD
128311
{planet+planet}, HD 160691 = mu Arae {planet+planet}, and HD
222404AB
= gamma Cephei {planet+star}. In each case the companion is
identified
as such by assuming that the minimum mass is the actual mass.
For
the last target, a known stellar binary system, the companion orbit
is
stable only if coplanar with the AB binary orbit.
NIC1/NIC2/NIC3
11330
NICMOS
Cycle 16 Extended Dark
This
takes a series of Darks in parallel to other instruments.
NIC1/NIC2/NIC3
8795
NICMOS
Post-SAA calibration - CR Persistence Part 6
A
new procedure proposed to alleviate the CR-persistence problem of
NICMOS.
Dark frames will be obtained immediately upon exiting the SAA
contour
23, and every time a NICMOS exposure is scheduled within 50
minutes
of coming out of the SAA. The darks will be obtained in parallel
in
all three NICMOS Cameras. The POST-SAA darks will be non- standard
reference
files available to users with a USEAFTER date/time mark. The
keyword
'USEAFTER=date/time' will also be added to the header of each
POST-SAA
DARK frame. The keyword must be populated with the time, in
addition
to the date, because HST crosses the SAA ~8 times per day so
each
POST-SAA DARK will need to have the appropriate time specified, for
users
to identify the ones they need. Both the raw and processed images
will
be archived as POST-SAA DARKSs. Generally we expect that all NICMOS
science/calibration
observations started within 50 minutes of leaving an
SAA
will need such maps to remove the CR persistence from the science i
mages.
Each observation will need its own CRMAP, as different SAA
passages
leave different imprints on the NICMOS detectors.
WFPC2
11040
Geometric
Distortion / Astrometry Closeout
These
observations will serve as a final characterization of the
geometric
distortion and astrometric calibration. The Omega-Cen inner
calibration
field is used. Filters F300W, F555W, and F814W are observed
at
5 roll angles spanning 180 degrees; F218W is observed at a single
roll
angle.
WFPC2
11083
The
Structure, Formation and Evolution of Galactic Cores and Nuclei
A surprising
result has emerged from the ACS Virgo Cluster Survey
{ACSVCS},
a program to obtain ACS/WFC gz imaging for a large, unbiased
sample
of 100 early-type galaxies in the Virgo Cluster. On subarcsecond
scales
{i.e., <0.1"-1"}, the HST brightness profiles vary systematically
from
the brightest giants {which have nearly constant surface brightness
cores}
to the faintest dwarfs {which have compact stellar nuclei}.
Remarkably,
the fraction of galaxy mass contributed by the nuclei in the
faint
galaxies is identical to that contributed by supermassive black
holes
in the bright galaxies {0.2%}. These findings strongly suggest
that
a single mechanism is responsible for both types of Central Massive
Object:
most likely internally or externally modulated gas inflows that
feed
central black holes or lead to the formation of "nuclear star
clusters".
Understanding the history of gas accretion, star formation
and
chemical enrichment on subarcsecond scales has thus emerged as the
single
most pressing question in the study of nearby galactic nuclei,
either
active or quiescent. We propose an ambitious HST program {199
orbits}
that constitutes the next, obvious step forward:
high-resolution,
ultraviolet {WFPC2/F255W} and infrared {NIC1/F160W}
imaging
for the complete ACSVCS sample. By capitalizing on HST's unique
ability
to provide high-resolution images with a sharp and stable PSF at
UV
and IR wavelengths, we will leverage the existing optical HST data to
obtain
the most complete picture currently possible for the history of
star
formation and chemical enrichment on these small scales. Equally
important,
this program will lead to a significant improvement in the
measured
structural parameters and density distributions for the stellar
nuclei
and the underlying galaxies, and provide a sensitive measure of
"frosting"
by young stars in the galaxy cores. By virtue of its superb
image
quality and stable PSF, NICMOS is the sole instrument capable of
the
IR observations proposed here. In the case of the WFPC2
observations,
high-resolution UV imaging {< 0.1"} is a capability unique
to
HST, yet one that could be lost at anytime.
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
11339
A
deep observation of NGC4261: understanding its unique X-ray source
population,
gas morphology, and jet properties
The
nearby early-type galaxy NGC4261 reveals strikingly asymmetric
distributions
of X-ray sources as seen with Chandra, and globular
clusters
(GC) as seen in the optical band. To address the link between
these
populations based on their spatial correlation, luminosity
function
and spectral properties, and to investigate
the possibility
that
this effect is due to the galaxy's merger history, we propose a
100ksec
Chandra ACIS-S3 exposure, which will detect X-ray sources down
to typical
LMXB luminosities (Lx~5E37 erg/s), and HST-WFPC2 observations
to
obtain a deep census of the GC population over the whole galaxy.
These
data will also allow a detailed study of its complex gaseous
component,
and provide information on the unique two-sided X-ray jet.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
11122
- GSacq (2,3,3) resulted in Fine Lock Back-up (2,0,2) using FGS 2
At acquisition
of Signal (360/19:28:15), GSAcq (2,3,3) scheduled from
360/19:23:54 - 19:31:08 had resulted in Fine Lock Back-up (2,0,2)
using
FGS 2. Received QF3STOPF & QSTOP flags. No 486 ESB messages
were
received. Pre-acquisition OBAD #1 values: V1 748.74, V2 -1591.73,
V3
754.26, RSS 1913.93. Pre-acquisition OBAD #2 values: V1 6.66, V2
-1.76,
V3 6.88, RSS 9.74.
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
07
07
FGS
REacq
08
08
OBAD
with Maneuver
30
30
SIGNIFICANT
EVENTS: (None)