Status Report

NASA Hubble Space Telescope Daily Report #4844

By SpaceRef Editor
April 30, 2009
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: 5am April 29 – 5am April 30, 2009 (DOY


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

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).


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be

HSTARS: (None)




FGS GSAcq 06 06
FGS REAcq 07 07
OBAD with Maneuver 26 26


SpaceRef staff editor.