Daily Report #4843

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT***** #4843

PERIOD COVERED: 5am April 28 - 5am April 29, 2009 (DOY
*************************** 118/0900z-119/0900z)

OBSERVATIONS SCHEDULED

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 11612

Eta Carinae's Continuing Instability and Recovery - the 2009 Event

Eta Carinae is the only really observable example of structural
recovery from a massive giant eruption, a "supernova imposter' event.
Moreover it is the only well-observed star above 100 Msun, and its
5.5-year-recurrent spectroscopic events provide extraordinary clues to
its surface instability. This truly unique combination of attributes
makes it valuable for understanding the most massive stars. A fresh
development arose a few years ago: The star has brightened much faster
than before, and appears to have entered a rapid stage in its
post-eruption recovery.

A spectroscopic event will occur at 2009.0, soon after the planned HST
servicing mission. Because of the recent secular trend, this event is
expected to differ from its well-observed 2003.5 predecessor. The
differences will be very important, because they offer clues to
very-massive-star structural instabilities that can't be observed in
any other known way.

Some of the needed observations require HST's high spatial resolution
and UV coverage. We propose an efficient, well-chosen set of STIS and
ACS observations around the critical time. If the servicing mission is
too late for the event, then a subset of the observations will still
be merited.

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 11983

An Imaging Survey of Protoplanetary Disks and Brown Dwarfs in the
Chamaeleon I Region

We propose to carry out a HST/WFPC2 survey of young brown dwarfs,
Class I and Class II sources in the Chamaelon I region, one of the
best-studied star-forming regions, in order to investigate the link
between disk evolution and the formation of substellar-mass objects.
We will use deep broad-band imaging in the I and z-equivalent HST
bands to unveil the unknown population of substellar binary
companions, down to a few Jupiter masses for separations of a few tens
of AU. We will also perform narrow-band imaging to directly detect
accreting circumstellar disks and jets around brown dwarfs, Class-I
and class-II objects. Chamaelon I is nearly coeaval of Orion (~1-2Myr)
but at ~1/3 its distance, allowing 3x higher resolution and 10x more
flux for comparable objects. Unlike Orion, low-mass objects and
protoplanetary disks in Chamaeleon I have been extensively studied
with Spitzer, but not yet with the HST. The Chamaeleon I region is an
ideal HST target, as it lies in the CVZ of the HST and therefore it is
easily accessible any time of the year with long orbits.

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:

11785 - GSAcq(2,3,2) scheduled from 119/05:03:25 - 05:11:30, failed to
RGA Hold due to Search Radius Limit Exceeded on FGS-2.

Observations Affected: Astrometry, Proposal ID# 11944

COMPLETED OPS REQUEST:

18420-0 - Disable SIC&DH Redundant Tray Heaters @ 118/20:13z
18421-0 - Reconfigure SIC&DH to Reply Bus B @ 118/20:15z

COMPLETED OPS NOTES: (None)

*********************** SCHEDULED***** SUCCESSFUL

FGS GSAcq************** 09***************** 08
FGS REAcq************** 04***************** 04
OBAD with Maneuver **** 26***************** 25

SIGNIFICANT EVENTS:

Flash Report: SIC&DH Reconfiguration - Redundant Heater Disable &
Reply Bus B

At 118/20:13:34 UTC, Ops Request 18420-0 was successfully completed,
disabling the SIC&DH redundant tray heaters. Immediately following, at
118:20:15:07 UTC, Ops Request 18421-0 was also successfully completed,
reconfiguring the SIC&DH Multiplexed Data Bus (MDB) to operations on
Reply Bus B.