HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4655
PERIOD COVERED: 5am July 17 - 5am July 18, 2008 (DOY
199/0900z-200/0900z)
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.
NIC1/NIC2 11172
Defining Classes of Long Period Variable Stars in M31
We propose a thrifty but information-packed investigation
{1440
exposures total} with NICMOS F205W, F160W and F110W
providing crucial
information about Long Period Variables in M31, at a level
of detail
that has recently allowed the discovery of new variable
star classes in
the Magellanic Clouds, a very different stellar
population. These
observations are buttressed by an extensive map of the
same fields with
ACS and WFPC2 exposures in F555W and F814W, and a massive
ground-based
imaging patrol producing well-sampled light curves for
more than 400,000
variable stars. Our primary goal is to collect sufficient
NIR data in
order to analyze and classify the huge number of
long-period variables
in our catalog {see below} through Period-Luminosity {P/L}
diagrams. We
will produce accurate P/L diagrams for both the bulge and
a progression
of locations throughout the disk of M31. These diagrams
will be similar
in quality to those currently in the Magellanic Clouds, with
their lower
metallicity, radically different star formation history,
and larger
spread in distance to the variables. M31 offers an
excellent chance to
study more typical disk populations, in a manner which
might be extended
to more distant galaxies where such variables are still
visible, probing
a much more evenly spread progenitor age distribution than
cepheids {and
perhaps useful as a distance scale alternative or
cross-check}. Our data
will also provide a massive and unique color-magnitude
dataset, and
allow us to confirm the microlensing nature of a large
sample of
candidate lensed sources in M31. We expect that this study
will produce
several important results, among them a better
understanding of P/L and
P/L-color relations for pulsating variables which are
essential to the
extragalactic distance ladder, will view these variables
at a common
distance over a range of metallicities {eliminating the
distance-error
vs. metallicity ambiguity between the LMC and SMC}, allow
further
insight into possible faint-variable mass-loss for higher
metallicities,
and in general produce a sample more typical of giant disk
galaxies
predominant in many studies.
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.
NIC3 11545
A NICMOS Survey of Newly-Discovered Young Massive Clusters
We are on the cusp of a revolution in massive star
research triggered by
2MASS and Spitzer/GLIMPSE, and now is the ideal time to
capitalize on
these projects by performing the first survey of massive
stars in young
stellar clusters throughout the Galactic plane. A search
of the 2MASS
and GLIMPSE surveys has produced over 450 newly-identified
massive
stellar cluster candidates in the Galactic plane which are
hidden from
our view at optical wavelengths due to extinction. Here we
propose a
program of 29 orbits to image the most promising candidate
clusters in
broad and narrow band filters using HST/NICMOS. We will be
complementing
these observations with approved Spitzer and Chandra
programmes,
numerous approved and planned ground-based spectroscopic
observations,
and state-of-the-art modelling. We expect to substantially
increase the
numbers of massive stars known in the Galaxy, including
main sequence
stars and post-main sequence stars in the Red Supergiant,
Luminous Blue
Variable and Wolf-Rayet stages. Ultimately, this programme
will address
many of the fundamental topics in astrophysics: the slope
to the initial
mass function (IMF), an upper-limit to the masses of
stars, the
formation and evolution of the most massive stars,
gamma-ray burst (GRB)
progenitors, the chemical enrichment of the interstellar
medium, and
nature of the first stars in the Universe.
WFPC2 11156
Monitoring Active Atmospheres on Uranus and Neptune
We propose Snapshot observations of Uranus and Neptune to
monitor
changes in their atmospheres on time scales of weeks and
months. Uranus
equinox is only months away, in December 2007. Hubble
Space Telescope
observations during the past several years {Hammel et al.
2005, Icarus
175, 284 and references therein} have revealed strongly
wavelength-dependent latitudinal structure, the presence
of numerous
visible-wavelength cloud features in the northern
hemisphere, at least
one very long-lived discrete cloud in the southern
hemisphere, and in
2006 the first dark spot ever seen on Uranus. Long-term
ground-based
observations {Lockwood and Jerzekiewicz, 2006, Icarus 180,
442; Hammel
and Lockwood 2007, Icarus 186, 291} reveal seasonal
brightness changes
whose origins are not well understood. Recent near-IR
images of
obtained using adaptive optics on the Keck Telescope,
together with HST
observations {Sromovsky et al. 2003, Icarus 163, 256 and
references
therein} which include previous Snapshot programs {GO
8634, 10170,
10534} show a general increase in activity at south
temperate latitudes
until 2004, when
Further Snapshot observations of these two dynamic planets
will
elucidate the nature of long-term changes in their zonal
atmospheric
bands and clarify the processes of formation, evolution,
and dissipation
of discrete albedo features.
WFPC2 11235
HST NICMOS Survey of the Nuclear Regions 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 enhanced star formation
and Active
Galactic Nuclei {AGN} activity, possibly triggered as the
objects
transform into massive S0 and elliptical merger remnants.
We propose
NICMOS NIC2 imaging of the nuclear regions of a complete
sample of 88
L_IR > 10^11.4 L_sun luminous infrared galaxies in the
IRAS Revised
Bright Galaxy Sample {RBGS: i.e., 60 micron flux density
> 5.24 Jy}.
This sample is ideal not only in its completeness and
sample size, but
also in the proximity and brightness of the galaxies. The
superb
sensitivity and resolution of NICMOS NIC2 on HST enables a
unique
opportunity to study the detailed structure of the nuclear
regions,
where dust obscuration may mask star clusters, AGN and
additional nuclei
from optical view, with a resolution significantly higher
than possible
with Spitzer IRAC. This survey thus provides a crucial
component to our
study of the dynamics and evolution of IR galaxies
presently underway
with Wide-Field, HST ACS/WFC and Spitzer IRAC observations
of these 88
galaxies. Imaging will be done with the F160W filter
{H-band} to examine
as a function of both luminosity and merger stage {i} the
luminosity and
distribution of embedded star clusters, {ii} the presence
of optically
obscured AGN and nuclei, {iii} the correlation between the
distribution
of 1.6 micron emission and the mid-IR emission as detected
by Spitzer
IRAC, {iv} the evidence of bars or bridges that may funnel
fuel into the
nuclear region, and {v} the ages of star clusters for
which photometry
is available via ACS/WFC observations. The NICMOS data,
combined with
the HST ACS, Spitzer, and GALEX observations of this
sample, will result
in the most comprehensive study of merging and interacting
galaxies to
date.
WFPC2 11800
Hubble Heritage imaging of NGC 3324 in the Carina Nebula
An ACS H-alpha mosaic of NGC 3324 already exists (HST
proposal 10475, PI
Nathan Smith). This program will use WFPC2 to obtain two
more filters
for this field.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
#11402 GSAcq (1,2,1) failed to RGA Hold due to QF1STOPF
Flag on FGS1
during LOS@ 199/16:07:01z.
The 199/15:32:20z GSAcq (1,2,1) and 199/17:50:16z REAcq
(1,2,1) failed
to RGA hold due to QF1STOPF flag on FGS 1. Received 486
ESB messages
1808 (TxG FHST Sanity Check Failed) and 1805 (FHST Moving
Target
Detected).
Possible observations affected: WFPC #120 127 Proposal
11800; and
NICMOS #110 Proposal # 8795.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 8 7
FGS REacq 7 6
OBAD with Maneuver 28 28
SIGNIFICANT EVENTS: (None)