Notice: Due to the conversion of some ACS WFC or HRC
observations into
WFPC2, or NICMOS observations after the loss of ACS CCD
science
capability in January, there may be an occasional
discrepancy between a
proposal's listed (and correct) instrument usage and the
abstract that
follows it.
HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4403
PERIOD COVERED: UT July 12, 2007 (DOY 193)
OBSERVATIONS SCHEDULED
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.
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.
NIC3 11080
Exploring the Scaling Laws of Star Formation
As a variety of surveys of the local and distant Universe
are
approaching a full census of galaxy populations, our
attention needs to
turn towards understanding and quantifying the physical
mechanisms that
trigger and regulate the large-scale star formation rates
{SFRs} in
galaxies.
WFPC2 10818
Very Young Globular Clusters in M31 ?
We propose to use HST's unique high spatial resolution
imaging
capabilities to conclusively confirm or refute the
presence of alleged
very young globular clusters in M31. Such young globular
clusters with
ages < 3 Gyr are not present in our galaxy, and, if
real, would lead to
a striking difference in the age distribution of the GCs
between M31 and
the
in M31 is confirmed through our proposed ACS imaging {now
WFPC2 imaging}
with HST, this would suggest major differences in the
history of
assembly of the two galaxies, with probable substantial
late accretion
into M31 which did not occur in our own galaxy.
WFPC2 10902
The Nearest Luminous Blue Compact Galaxies: A Window on
Galaxy Formation
As we move to intermediate and high redshifts, Luminous
Blue Compact
Galaxies {LBCGs} become increasingly common. The nearest
LBCGs, with
their violent starbursts and rich populations of super
star clusters
{SSCs} and globular clusters {GCs}, thus provide ideal
laboratories for
studying galaxy evolution. Many LBCGs appear to be
involved in mergers
between dwarf galaxies, triggering their starbursts. The
starburst
regions in LBCGs consist of numerous young star clusters,
whose
populations are both easily measurable with HST and easily
modelled.
Studying cluster populations provides a powerful probe of
the starburst
and merger history which is possible neither for closer
objects {of
which there are too few} or for those at high redshift
{which are too
far away}. We have previously studied the closest LBCG
with WFPC2 and
found hundreds of bright compact SSCs and GCs. In
particular, we found a
population of intermediate-age {~2 Gyr} GCs, indicating a
past event of
massive cluster formation. We now propose a
multi-wavelength study of
the three other LBCGs with the highest known number of
SSCs. The
extinction is small in these galaxies and age estimates
robust. The age
distribution of GCs and SSCs will be used to study the
past evolution of
the galaxies. For each LBCG, we will map its cluster
formation history,
unveiling its merger and starburst history, and thereby
shed light on
some of the processes involved in galaxy evolution at high
redshift.
WFPC2 11079
Treasury Imaging of Star Forming Regions in the Local
Group:
Complementing the GALEX and NOAO Surveys
We propose to use WFPC2 to image the most interesting
star-forming
regions in the Local Group galaxies, to resolve their
young stellar
populations. We will use a set of filters including F170W,
which is
critical to detect and characterize the most massive
stars, to whose hot
temperatures colors at longer wavelengths are not
sensitive. WFPC2's
field of view ideally matches the typical size of the
star-forming
regions, and its spatial resolution allows us to measure
indvidual
stars, given the proximity of these galaxies. The
resulting H-R diagrams
will enable studies of star- formation properties in these
regions,
which cover largely differing metallicities {a factor of
17, compared to
the factor of 4 explored so far} and characteristics. The
results will
further our understanding of the star-formation process,
of the
interplay between massive stars and environment, the
properties of dust,
and will provide the key to interpret integrated
measurements of
star-formation indicators {UV, IR, Halpha} available for
several
hundreds more distant galaxies. Our recent deep surveys of
these
galaxies with GALEX {FUV, NUV} and ground-based imaging
{UBVRI, Halpha,
[OIII] and [SII]} provided the identification of the most
relevant SF
sites. In addition to our scientific analysis, we will
provide catalogs
of HST photometry in 6 bands, matched corollary
ground-based data, and
UV, Halpha and IR integrated measurements of the
associations, for
comparison of integrated star-formation indices to the resolved
populations. We envisage an EPO component.
WFPC2 11178
Probing Solar System History with Orbits, Masses, and
Colors of
Transneptunian Binaries
The recent discovery of numerous transneptunian binaries
{TNBs} opens a
window into dynamical conditions in the protoplanetary
disk where they
formed as well as the history of subsequent events which
sculpted the
outer Solar System and emplaced them onto their present
day heliocentric
orbits. To date, at least 47 TNBs have been discovered,
but only about a
dozen have had their mutual orbits and separate colors
determined,
frustrating their use to investigate numerous important
scientific
questions. The current shortage of data especially
cripples scientific
investigations requiring statistical comparisons among the
ensemble
characteristics. We propose to obtain sufficient
astrometry and
photometry of 23 TNBs to compute their mutual orbits and
system masses
and to determine separate primary and secondary colors,
roughly tripling
the sample for which this information is known, as well as
extending it
to include systems of two near-equal size bodies. To make
the most
efficient possible use of HST, we will use a
optimally schedule our observations.
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)
SCHEDULED
SUCCESSFUL
FGS
GSacq
10
10
FGS
REacq
4
4
OBAD with Maneuver
28
28
COMPLETED OPS NOTES: (None)
SIGNIFICANT EVENTS: (None)