HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4703
PERIOD COVERED: 5am September 24 - 5am September 25, 2008
(DOY 268/0900z-269/0900z)
OBSERVATIONS SCHEDULED
FGS 11211
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.
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 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 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 11202
The Structure of Early-type Galaxies: 0.1-100 Effective
Radii
The structure, formation and evolution of early-type
galaxies is still
largely an open problem in cosmology: how does the
Universe evolve from
large linear scales dominated by dark matter to the highly
non-linear
scales of galaxies, where baryons and dark matter both
play important,
interacting, roles? To understand the complex physical
processes
involved in their formation scenario, and why they have
the tight
scaling relations that we observe today {e.g. the
Fundamental Plane}, it
is critically important not only to understand their
stellar structure,
but also their dark-matter distribution from the smallest
to the largest
scales. Over the last three years the SLACS collaboration
has developed
a toolbox to tackle these issues in a unique and
encompassing way by
combining new non-parametric strong lensing techniques,
stellar
dynamics, and most recently weak gravitational lensing,
with
high-quality Hubble Space Telescope imaging and VLT/Keck
spectroscopic
data of early-type lens systems. This allows us to break
degeneracies
that are inherent to each of these techniques separately
and probe the
mass structure of early-type galaxies from 0.1 to 100
effective radii.
The large dynamic range to which lensing is sensitive
allows us both to
probe the clumpy substructure of these galaxies, as well
as their
low-density outer haloes. These methods have convincingly
been
demonstrated, by our team, using smaller pilot-samples of
SLACS lens
systems with HST data. In this proposal, we request
observing time with
WFPC2 and NICMOS to observe 53 strong lens systems from
SLACS, to obtain
complete multi-color imaging for each system. This would
bring the total
number of SLACS lens systems to 87 with completed HST
imaging and
effectively doubles the known number of galaxy-scale
strong lenses. The
deep HST images enable us to fully exploit our new
techniques, beat down
low-number statistics, and probe the structure and
evolution of early-
type galaxies, not only with a uniform data-set an order
of magnitude
larger than what is available now, but also with a fully
coherent and
self-consistent methodological approach!
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 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 11316
HST Cycle 16 & Pre-SM4 Optical Monitor
This is a continuation of the Cycle 15 & pre-SM4
Optical Monitor, 11020.
Please see that proposal for a more complete description
of the
observing strategy. The 6 visits comprising this proposal
observe two
single standard stars with WFPC2/PC in order to establish
overall OTA
focal length for the purposes of focus maintenance. The
goal of this
monitoring before SM4 is to establish a best estimate of
the OTA focus
entering SMOV.
WFPC2 11544
The Dynamical Legacy of Star Formation
We propose to use WFPC2 to conduct a wide-field imaging
survey of the
young cluster IC348. This program, in combination with
archival HST
observations, will allow us to measure precise proper
motions for
individual cluster members, characterizing the
intra-cluster velocity
dispersion and directly studying the dynamical signatures
of star
formation and early cluster evolution. Our projected
astrometric
precision (~1 mas in each epoch) will allow us to calculate
individual
stellar velocities to unprecedented precision (<0.5
mas/yr; <1 km/s) and
directly relate these velocities to observed spatial
substructure within
the cluster. This survey will also allow us to probe
small-scale star
formation physics by searching for high-velocity stars
ejected from
decaying multiple systems, expanding our knowledge of
multiplicity in
dense environments, and identifying new substellar and
planetary-mass
cluster members based on kinematic membership tests.
WFPC2 11796
WFPC2 Cycle 16 Decontaminations and Associated
Observations
This proposal is for the WFPC2 decons. Also included are
instrument
monitors tied to decons: photometric stability check,
focus monitor,
pre- and post-decon internals (bias, intflats, kspots,
& darks), UV
throughput check, VISFLAT sweep, and internal UV flat
check.
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
13
13
FGS
REacq
02
02
OBAD with Maneuver 30
30
SIGNIFICANT EVENTS: (None)