HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4785
PERIOD COVERED: 5am February 4 - 5am February 5, 2009 (DOY
035/1000z-036/1000z)
OBSERVATIONS SCHEDULED
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.
FGS 11942
Increasing the Accuracy of HST Astrometry with FGS1R
We propose to observe six exoplanetary system host stars
and two
planetary nebulae central stars with FGS1r. All objects
have been
previously observed under proposals GO-09233, -09969,
-10989, and
-11210. These observations will significantly extend the
time baseline,
permitting improvements in the determination of proper
motion. This
systematic motion must be removed to get at the
perturbation of
interest, either due to exoplanetary companions or the
orbital motion of
the Earth (parallax). In most cases the perturbation
orbits will also
improve. We improve either companion mass or PN parallax.
For one
target, GJ 876, theoretical dynamical modelers have
proposed an
inclination closer to 50 degrees, while FGS3 measurements
indicated an
inclination closer to 84 degrees. These new data, once
combined with our
older FGS3 data, will permit an independent remeasurement
of the
inclination of the outermost companion, and a
re-evaluation of widely
used dynamical algorithms.
NIC3 11236
Did Rare, Large Escape-Fraction Galaxies Reionize the Universe?
Lyman continuum photons produced in massive starbursts may
have played a
dominant role in the reionization of the Universe.
Starbursts are
important contributors to the ionizing metagalactic
background at lower
redshifts as well. However, their contribution to the
background depends
upon the fraction of ionizing radiation that escapes from
the intrinsic
opacity of galaxies below the Lyman limit. Current surveys
suggest that
the escape fraction is close to zero in most galaxies,
even among young
starbursts, but is large in 15-25% of them. Non-uniform
escape fractions
are expected as a result of violent events creating clear
paths in small
parts of galaxies. The number of galaxies observed with
high escape
fraction will result from the combination of the intrinsic
number with
clear lines of sight and their orientation with respect to
the observer.
We propose to measure the fraction of escaping Lyman
continuum radiation
in a large sample (47) of z~0.7 starbursts in the COSMOS
field. These
compact UV-luminous galaxies are good analogs to high
redshift LBGs.
Using the SBC/PR130L we can quickly (1-4 orbits) detect
relative escape
fractions (f_LC/f_1500) of 25% or more. This will be the
first
measurement of the escape fraction in sources between z=1
and the local
universe. We expect ~10 detections. Stacking will set
limits of <4% on
the relative escape fraction in the rest. We will
correlate the LC
detections with the properties of the galaxies. By
targeting z~0.7 in
COSMOS, we will have tremendous ancillary information on
those sources.
A non-detection in all sources would be significant (99%
confidence).
This would imply that QSOs provide the overwhelming
majority of ionizing
radiation at z<1, requiring substantial evolution in
the processes
within Lyman break galaxies which allow large escape
fractions at high
redshift.
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 11944
Binaries at the Extremes of the H-R Diagram
We propose to use HST/Fine Guidance Sensor 1r to survey
for binaries
among some of the most massive, least massive, and oldest
stars in our
part of the Galaxy. FGS allows us to spatially resolve
binary systems
that are too faint to observe using ground-based, speckle
or optical
long baseline interferometry, and too close to resolve
with AO. We
propose a SNAP-style program of single orbit FGS TRANS
mode observations
of very massive stars in the cluster NGC 3603, luminous
blue variables,
nearby low mass main sequence stars, cool subdwarf stars,
and white
dwarfs. These observations will help us to (1) identify
systems suitable
for follow up studies for mass determination, (2) study
the role of
binaries in stellar birth and in advanced evolutionary
states, (3)
explore the fundamental properties of stars near the main
sequence-brown
dwarf boundary, (4) understand the role of binaries for
X-ray bright
systems, (5) find binaries among ancient and nearby
subdwarf stars, and
(6) help calibrate the white dwarf mass - radius relation.
WFPC2 11971
A Rare Mutual Event between Satellites of the Dwarf Planet
Haumea
The dwarf planet Haumea has a fascinating history,
including the
formation of two large satellites by an ancient
mantle-shattering
collision. Haumea also has an exciting future with many
observable
mutual events between Haumea and the smaller inner moon
Namaka predicted
for the next several years. The Haumea-Namaka mutual
events will provide
a wealth of information that is otherwise unattainable:
the size, shape,
and spin pole of Haumea; the size, albedo, and density of
Namaka; and
precise orbital constraints. The orbital orientation is
not as favorable
for the outer, larger satellite Hi'iaka, but the last two
possible
mutual events between Hi'iaka and Namaka occur in 2009 and
will not
occur again for decades. We propose a short {5-orbit}
WFPC2 resolved
photometry program to observe the first of these events,
which will
occur with an estimated ~75% probability. Even catching a
partial event
will measure the density of Hi'iaka to within ~15% and
provide unique
insight in the formation and evolution of this exciting
system.;
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
04
04
FGS
REacq
10
10
OBAD with Maneuver
28
28
SIGNIFICANT EVENTS: (None)