Status Report

NASA Hubble Space Telescope Daily Report #4694

By SpaceRef Editor
September 15, 2008
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HUBBLE SPACE TELESCOPE DAILY REPORT #4694

Continuing to collect World Class Science

PERIOD COVERED: 5am September 11 – 5am September 12, 2008 (DOY 255/0900z-256/0900z)

OBSERVATIONS SCHEDULED

ACS/SBC 11158

HST Imaging of UV Emission in Quiescent Early-type Galaxies

We have constructed a sample of early type galaxies at z~0.1 that have blue UV-optical colors, yet also show no signs of optical emission, or extended blue light. We have cross-correlated the SDSS catalog and the Galaxy Evolution Explorer Medium Imaging Survey to select a sample of galaxies where this UV emission is strongest. The origin of the UV rising flux in these galaxies continues to be debated, and the possibility that some fraction of these galaxies may be experiencing low levels of star formation cannot be excluded. There is also a possibility that low level AGN activity {as evidenced by a point source} is responsible We propose to image the UV emission using the HST/SBC and to explore the morphology of the UV emission relative to the optical light.

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.

WFPC2 11218

Snapshot Survey for Planetary Nebulae in Globular Clusters of the Local Group

Planetary nebulae {PNe} in globular clusters {GCs} raise a number of interesting issues related to stellar and galactic evolution. The number of PNe known in Milky Way GCs, 4, is surprisingly low if one assumes that all stars pass through a PN stage. However, it is likely that the remnants of stars now evolving in Galactic GCs leave the AGB so slowly that any ejected nebula dissipates long before the star becomes hot enough to ionize it. Thus there should not be ANY PNe in Milky Way GCs–but there are four! It has been suggested that these PNe are the result of mergers of binary stars within GCs, i.e., that they are descendants of blue stragglers. The frequency of occurrence of PNe in external galaxies poses more questions, because it shows a range of almost an order of magnitude. I propose a Snapshot survey aimed at discovering PNe in the GC systems of Local Group galaxies more distant than the Magellanic Clouds. These clusters, some of which may be much younger than their counterparts in the Milky Way, might contain many more PNe than those of our own galaxy. I will use the standard technique of emission-line and continuum imaging, which easily discloses PNe.

WFPC2 11544

The Dynamical Legacy of Star Formation

We propose to use WFPC2 to conduct a wide-field imaging survey of the young cluster IC348. This program, in combination with archival HST observations, will allow us to measure precise proper motions for individual cluster members, characterizing the intra-cluster velocity dispersion and directly studying the dynamical signatures of star formation and early cluster evolution. Our projected astrometric precision (~1 mas in each epoch) will allow us to calculate individual stellar velocities to unprecedented precision (<0.5 mas/yr; <1 km/s) and directly relate these velocities to observed spatial substructure within the cluster. This survey will also allow us to probe small-scale star formation physics by searching for high-velocity stars ejected from decaying multiple systems, expanding our knowledge of multiplicity in dense environments, and identifying new substellar and planetary-mass cluster members based on kinematic membership tests.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11485 GSACQ(1,2,2) fails to gyro control

GSACQ(1,2,2) at 255/19:05:51 failed to RGA control at 19:09:50 with QF1STOPF and QSTOP flags set. #44 commands did not change since previous acquisition.

REACQ(1,2,2) at 20:28:34 was successful.

WFPC was in safemode at the time. (Observations that would have been affected: WFPC 17 and 18, proposal 11218.)

COMPLETED OPS REQUEST:

18274-1 – Dump ESM/8051 History and Min/Max Buffers @ 255/09:29z

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL

FGS GSacq               09             08
FGS REacq               05             05
OBAD with Maneuver      29             29

SIGNIFICANT EVENTS:

Flash Report:

ACS Science has Resumed Following Nominal ACS Recovery ACS Recovery was performed via the SMS as planned at 255/11:00 UTC and ACS Science subsequently resumed at 11:33 UTC. WFPC was in safemode at the time.

SpaceRef staff editor.