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)