HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4844
PERIOD COVERED: 5am April 29 - 5am April 30, 2009 (DOY
119/0900z-120/0900z)
OBSERVATIONS SCHEDULED
FGS 11788
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 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 for 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 11973
SAINTS - Supernova 1987A INTensive Survey
SAINTS is a program to observe SN 1987A, the brightest
supernova since
1604, as it matures into the youngest supernova remnant at
age 21. HST
is the essential tool for resolving SN1987A's many
physical components.
A violent encounter is underway between the fastest-moving
debris and
the circumstellar ring: shocks excite
"hotspots." Radio, optical,
infrared and X-ray fluxes have been rising rapidly: we
have organized
Australia Telescope, HST, VLT, Spitzer, and Chandra
observations to
understand the several emission mechanisms at work. Photons
from the
shocked ring will excite previously invisible gas outside
the ring,
revealing the true extent of the mass loss that preceded
the explosion
of Sanduleak -69 202. This will help test ideas for the
progenitor of SN
1987A. The inner debris, excited by radioactive isotopes
from the
explosion, is now resolved and seen to be aspherical,
providing direct
evidence on the shape of the explosion itself. Questions
about SN 1987A
remain unanswered. A rich and unbroken data set from
SAINTS will help
answer these central questions and will build an archive
for the future
to help answer questions we have not yet thought to ask.
WFPC2 11979
WFPC2 Imaging of Fomalhaut b: Determining its Orbit and
Testing for
H-alpha Emission
Fomalhaut is a bright nearby star that harbors a belt of
dusty material
with a morphology that has been used to predict the
presence of a
shepherding planet. With ACS/HRC coronagraphy, we have
achieved the
direct detection of a planet candidate (Fomalhaut b) in
F606W and F814W.
The planet candidate lies 18 AU interior to the dust belt
and we detect
counterclockwise orbital motion in two epochs of
observations (2004 and
2006). Fomalhaut b has mass no greater than three Jupiter
masses based
on an analysis of its luminosity, including non-detections
at infrared
wavelengths, and the dynamical argument that a
significantly more
massive object would disrupt the dust belt. Variability at
optical
wavelengths and the brightness in the F606W passband
suggest additional
sources of luminosity such as starlight reflected from a
circumplanetary
ring system. A second possibility that has been invoked
for substellar
objects is a significant contribution of H-alpha emission.
Here we
propose follow-up WFPC2 observations to test the
possibility that the
F606W flux is contaminated by H-alpha emission. We
demonstrate that the
detection of Fomalhaut b using WFPC2 is feasible using
roll
deconvolution. Furthermore, a detection of Fomalhaut b in
2009 will
provide a crucial third epoch for astrometry. With the
existing two
epochs of data, the orbit of Fomalhaut b cannot be
determined uniquely.
The third epoch will be used to test the prediction of
apsidal alignment
and more accurately determine the dynamical mass of
Fomalhaut b. If
apsidal mis-alignment is found between the planet and the
belt, this
result would point to the existence of still other planets
lurking
unseen in the Fomalhaut system.
WFPC2 11988
Searching for Intermediate Mass Black Holes in Globular
Clusters via
Proper Motions
The unambiguous detection of an intermediate mas black
hole (IMBH) in a
globular star cluster would be a major achievement for the
Hubble Space
Telescope. It is critical to know whether or not IMBHs
exist in the
centers of clusters in order to understand the dynamical
evolution of
dense stellar systems. Also, n IMBH detection would prove
the existence
of BHs in an entirely new mass range. Observationally, the
search has
been hampered by the low number of stars with known
velocities in the
central few arcseconds. This limits measurements of the
stellar velocity
dispersion in the region where the gravitational influence
of any IMBH
would be felt. Existing IMBH claims in the literature have
all been
called into question, and have all been based on
line-of-sight
velocities from spectroscopy. In cycle 13, we obtained
ACS/HRC
observations for 5 nearby Galactic globular clusters for a
new proper
motion study. Here, we request WFPC2/PC observations of
these clusters,
all of which are observable in Feb-May 2009. This 4 year
baseline will
allow us to measure the proper motions of stars into the
very center of
each cluster, and either detect or place firm constraints
on the
presence of an IMBH. In addition, we will determine
whether or not the
clusters rotate or show any anisotropy in their motions.
Our small (<75
orbit) program meets the criteria of addressing high
impact science
(IMBH detection) using innovative methods (proper
motions).
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 06
06
FGS
REAcq
07
07
OBAD with Maneuver
26
26
SIGNIFICANT EVENTS: (None)