HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4734
PERIOD COVERED: 5am November 7 - 5am November 10, 2008
(DOY
312/1000z-315/1000z)
OBSERVATIONS SCHEDULED
FGS 11945
Asteroseismology of Extrasolar Planet Host Stars
Detections of stellar oscillations, although a very
demanding task in
terms of observing time, offers a return of more accurate
knowledge
about the structure of stars than can be obtained in any
other way. In
particular, detecting the 10-15 highest amplitude modes in
solar-like
stars to signal-to-noise of just a few sigma each allows
robust
constraints on the stellar density to <1%, and the
stellar age to within
5-10% of its main sequence lifetime. Ten day observing
runs using the
FGS as a photometer on any of the 5 best transiting planet
systems would
enable these asteroseismology returns. From more precisely
observed
transit shapes than can be obtained from the ground a
completely
independent constraint on stellar density to ~1% can be
obtained. The
long observation sets required for asteroseismology also
provide an
excellent opportunity of detecting transits from other
planets, e.g.
hypothesized inner -orbit Hot Earths, should any exist.
FGS 11901/11212
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 11797
Supplemental WFPC2 CYCLE 16 Intflat Linearity Check and
Filter Rotation
Anomaly Monitor
Supplemental observations to 11029, to cover period from
Aug 08 to SM4.
Intflat observations will be taken to provide a linearity
check: the
linearity test consists of a series of intflats in F555W,
in each gain
and each shutter. A combination of intflats, visflats, and
earthflats
will be used to check the repeatability of filter wheel
motions.
(Intflat sequences tied to decons, visits 1-18 in prop
10363, have been
moved to the cycle 15 decon proposal 11022 for easier
scheduling.)
Note: long-exposure WFPC2 intflats must be scheduled
during ACS anneals
to prevent stray light from the WFPC2 lamps from
contaminating long ACS
external exposures.
Note: These are supplemental observations to cover June to
SM4 (Oct 8
'08) + 6 months.
FGS 11789
An Astrometric Calibration of Population II Distance
Indicators
In 2002 HST produced a highly precise parallax for RR
Lyrae. That
measurement resulted in an absolute magnitude, M(V)=
0.61+/-0.11, a
useful result, judged by the over ten refereed citations
each year
since. It is, however, unsatisfactory to have the direct,
parallax-based, distance scale of Population II variables
based on a
single star. We propose, therefore, to obtain the
parallaxes of four
additional RR Lyrae stars and two Population II Cepheids,
or
stars. The Population II Cepheids lie with the RR Lyrae
stars on a
common K-band Period-Luminosity relation. Using these
parallaxes to
inform that relationship, we anticipate a zero-point error
of 0.04
magnitude. This result should greatly strengthen
confidence in the
Population II distance scale and increase our
understanding of RR Lyrae
star and Pop II Cepheid astrophysics.
WFPC2 11289
SL2S: The Strong Lensing Legacy Survey
Recent systematic surveys of strong galaxy-galaxy lenses
{CLASS, SLACS,
GOODS, etc.} are producing spectacular results for galaxy
masses roughly
below a transition mass M~10^13 Mo. The observed lens
properties and
their evolution up to z~0.2, consistent with numerical
simulations, can
be described by isothermal elliptical potentials. In
contrast, modeling
of giant arcs in X-ray luminous clusters {halo masses M
>~10^13 Mo}
favors NFW mass profiles, suggesting that dark matter
halos are not
significantly affected by baryon cooling. Until recently,
lensing
surveys were neither deep nor extended enough to probe the
intermediate
mass density regime, which is fundamental for
understanding the assembly
of structures. The CFHT Legacy Survey now covers 125
square degrees, and
thus offers a large reservoir of strong lenses probing a
large range of
mass densities up to z~1. We have extracted a list of 150
strong lenses
using the most recent CFHTLS data release via automated
procedures.
Following our first SNAPSHOT proposal in cycle 15, we
propose to
continue the Hubble follow-up targeting a larger list of
130 lensing
candidates. These are intermediate mass range candidates
{between
galaxies and clusters} that are selected in the redshift
range of 0.2-1
with no a priori X-ray selection. The HST resolution is
necessary for
confirming the lensing candidates, accurate modeling of
the lenses, and
probing the total mass concentration in galaxy groups up
to z~1 with the
largest unbiased sample available to date.
WFPC2 11203
A Search for Circumstellar Disks and Planetary-Mass
Companions around
Brown Dwarfs in Taurus
During a 1-orbit program in Cycle 14, we used WFPC2 to
obtain the first
direct image of a circumstellar disk around a brown dwarf.
These data
have provided fundamental new constraints on the formation
process of
brown dwarfs and the properties of their disks. To search
for additional
direct detections of disks around brown dwarfs and to
search for
planetary-mass companions to these objects, we propose a
WFPC2 survey of
32 brown dwarfs in the Taurus star-forming region.
ACS/SBC WFPC2 11175
UV Imaging to Determine the Location of Residual Star
Formation in
Galaxies Recently Arrived on the Red Sequence
We have identified a sample of low-redshift {z = 0.04 -
0.10} galaxies
that are candidates for recent arrival on the red
sequence. They have
red optical colors indicative of old stellar populations,
but blue
UV-optical colors that could indicate the presence of a
small quantity
of continuing or very recent star formation. However,
their spectra lack
the emission lines that characterize star-forming
galaxies. We propose
to use ACS/SBC to obtain high-resolution imaging of the UV
flux in these
galaxies, in order to determine the spatial distribution
of the last
episode of star formation. WFPC2 imaging will provide B, V,
and I
photometry to measure the main stellar light distribution
of the galaxy
for comparison with the UV imaging, as well as to measure
color
gradients and the distribution of interstellar dust. This
detailed
morphological information will allow us to investigate the
hypothesis
that these galaxies have recently stopped forming stars
and to compare
the observed distribution of the last star formation with
predictions
for several different mechanisms that may quench star
formation in
galaxies.
ACS/SBC 11158
HST Imaging of UV Emission in Quiescent Early-type
Galaxies
We have constructed a sample of early type galaxies at
z~0.1 that have
blue UV-optical colors, yet also show no signs of optical
emission, or
extended blue light. We have cross-correlated the SDSS
catalog and the
Galaxy Evolution Explorer Medium Imaging Survey to select
a sample of
galaxies where this UV emission is strongest. The origin
of the UV
rising flux in these galaxies continues to be debated, and
the
possibility that some fraction of these galaxies may be
experiencing low
levels of star formation cannot be excluded. There is also
a possibility
that low level AGN activity {as evidenced by a point
source} is
responsible We propose to image the UV emission using the
HST/SBC and to
explore the morphology of the UV emission relative to the
optical light.
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.
WFPC2 11130
AGNs with Intermediate-mass Black Holes: Testing the Black
Hole-Bulge
Paradigm, Part II
The recent progress in the study of central black holes in
galactic
nuclei has led to a general consensus that supermassive
{10^6-10^9 solar
mass} black holes are closely connected with the formation
and
evolutionary history of large galaxies, especially their
bulge
component. Two outstanding issues, however, remain
unresolved. Can
central black holes form in the absence of a bulge? And
does the mass
function of central black holes extend below 10^6 solar
masses?
Intermediate-mass black holes {<10^6 solar masses}, if
they exist, may
offer important clues to the nature of the seeds of
supermassive black
holes. Using the SDSS, our group has successfully
uncovered a new
population of AGNs with intermediate-mass black holes that
reside in
low-luminosity galaxies. However, very little is known
about the
detailed morphologies or structural parameters of the host
galaxies
themselves, including the crucial question of whether they
have bulges
or not. Surprisingly, the majority of the targets of our
Cycle 14 pilot
program have structural properties similar to dwarf
elliptical galaxies.
The statistics from this initial study, however, are
really too sparse
to reach definitive conclusions on this important new
class of black
holes. We wish to extend this study to a larger sample, by
using the
Snapshot mode to obtain WFPC2 F814W images from a parent
sample of 175
AGNs with intermediate- mass black holes selected from our
final SDSS
search. We are particularly keen to determine whether the
hosts contain
bulges, and if so, how the fundamental plane properties of
the host
depend on the mass of their central black holes. We will
also
investigate the environment of this unique class of AGNs.
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.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
11569 - GSAcq(2,1,2) failed, Search Radius Limit exceeded
on FGS-1
GSAcq(2,1,2)scheduled at 313/06:17:45 -
06:25:50 failed to RGA Hold due
to Search Radius Limit exceeded limit on FGS-1,
resulting in blocking of
ACS fold mechanism and take data flag down.
Possible Observations affected: ACS #4,
Proposal #11151.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 35 34
FGS REacq 06 06
OBAD with Maneuver 74 74
SIGNIFICANT EVENTS: (None)