NASA Hubble Space Telescope Daily Status Report #4657
HUBBLE SPACE TELESCOPE DAILY REPORT #4657
Continuing to collect World Class Science
PERIOD COVERED: 5am July 21 – 5am July 22, 2008 (DOY 203/0900z-204/0900z)
OBSERVATIONS SCHEDULED
ACS/SBC 11131
Star Formation at Large Radii in Cooling Flow Brightest Cluster Galaxies
We propose to take deep ACS FUV images of the bright central galaxies in two powerful cooling flow clusters for which we have VLT UBR images, with the object of determining whether the UV excesses we observe at large radii (>15kpc) are caused by young stars, ultrahot (WR) stars, or an as yet unknown source. Current models of excess UV light at the AGN-dominated centers of these galaxies cannot easily be extended to large radii. New understanding of star formation in these clusters will be directly applicable to scenarios of galaxy formation in the early universe.
WFPC2 11024
WFPC2 CYCLE 15 INTERNAL MONITOR
This calibration proposal is the Cycle 15 routine internal monitor for WFPC2, to be run weekly to monitor the health of the cameras. A variety of internal exposures are obtained in order to provide a monitor of the integrity of the CCD camera electronics in both bays {both gain 7 and gain 15 — to test stability of gains and bias levels}, a test for quantum efficiency in the CCDs, and a monitor for possible buildup of contaminants on the CCD windows. These also provide raw data for generating annual super-bias reference files for the calibration pipeline.
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.
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA Calibration – CR Persistence Part 6
A new procedure proposed to alleviate the CR-persistence problem of NICMOS. Dark frames will be obtained immediately upon exiting the SAA contour 23, and every time a NICMOS exposure is scheduled within 50 minutes of coming out of the SAA. The darks will be obtained in parallel in all three NICMOS Cameras. The POST-SAA darks will be non-standard reference files available to users with a USEAFTER date/time mark. The keyword ‘USEAFTER=date/time’ will also be added to the header of each POST-SAA DARK frame. The keyword must be populated with the time, in addition to the date, because HST crosses the SAA ~8 times per day so each POST-SAA DARK will need to have the appropriate time specified, for users to identify the ones they need. Both the raw and processed images will be archived as POST-SAA DARKSs. Generally we expect that all NICMOS science/calibration observations started within 50 minutes of leaving an SAA will need such maps to remove the CR persistence from the science images. Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors.
NIC2 11547
Characterizing Pre-Main Sequence Populations in Stellar Associations of the Large Magellanic Cloud
The Large Magellanic Cloud (LMC) offers an extremely rich sample of resolved low-mass stars (below 1 Solar Mass) in the act of formation that has not been explored sufficiently yet. These pre-main sequence (PMS) stars provide a unique snapshot of the star formation process, as it is being recorded for the last ~20 Myr, and they give important information on the low-mass Initial Mass Function (IMF) of their host stellar systems. Studies of young, rich LMC clusters like 30 Doradus are crowding limited, even at the angular resolution facilitated by HST in the optical. To learn more about low-mass PMS stars in the LMC, one has to study less crowded regions like young stellar associations. We propose to employ WFPC2 to obtain deep photometry (V ~ 25.5 mag) of four selected LMC stellar associations in order to perform an original optical analysis of their red PMS and blue bright MS stellar populations. With these observations we aim at a comprehensive study, which will add substantial information on the most recent star formation and the IMF in the LMC. The data reduction and analysis will be performed with a 2D photometry software package especially developed by us for WFPC2 imaging of extended stellar associations with variable background. Our targets have been selected optimizing a combination of criteria, namely spatial resolution, crowding, low extinction, nebular contamination, and background confusion in comparison to other regions in the Local Group. Parallel NICMOS imaging will provide additional information on near-infrared properties of the stellar population in the regions surrounding these systems.
NIC3 11545
A NICMOS Survey of Newly-Discovered Young Massive Clusters
We are on the cusp of a revolution in massive star research triggered by 2MASS and Spitzer/GLIMPSE, and now is the ideal time to capitalize on these projects by performing the first survey of massive stars in young stellar clusters throughout the Galactic plane. A search of the 2MASS and GLIMPSE surveys has produced over 450 newly-identified massive stellar cluster candidates in the Galactic plane which are hidden from our view at optical wavelengths due to extinction. Here we propose a program of 29 orbits to image the most promising candidate clusters in broad and narrow band filters using HST/NICMOS. We will be complementing these observations with approved Spitzer and Chandra programs, numerous approved and planned ground-based spectroscopic observations, and state-of-the-art modeling. We expect to substantially increase the numbers of massive stars known in the Galaxy, including main sequence OB stars and post-main sequence stars in the Red Supergiant, Luminous Blue Variable and Wolf-Rayet stages. Ultimately, this program will address many of the fundamental topics in astrophysics: the slope to the initial mass function (IMF), an upper-limit to the masses of stars, the formation and evolution of the most massive stars, gamma-ray burst (GRB) progenitors, the chemical enrichment of the interstellar medium, and nature of the first stars in the Universe.
WFPC2 11070
WFPC2 CYCLE 15 Standard Darks – part II
This dark calibration program obtains dark frames every week in order to provide data for the ongoing calibration of the CCD dark current rate, and to monitor and characterize the evolution of hot pixels. Over an extended period these data will also provide a monitor of radiation damage to the CCDs.
WFPC2 11113
Binaries in the Kuiper Belt: Probes of Solar System Formation and Evolution
The discovery of binaries in the Kuiper Belt and related small body populations is powering a revolutionary step forward in the study of this remote region. Three quarters of the known binaries in the Kuiper Belt have been discovered with HST, most by our snapshot surveys. The statistics derived from this work are beginning to yield surprising and unexpected results. We have found a strong concentration of binaries among low-inclination Classicals, a possible size cutoff to binaries among the Centaurs, an apparent preference for nearly equal mass binaries, and a strong increase in the number of binaries at small separations. We propose to continue this successful program in Cycle 16; we expect to discover at least 13 new binary systems, targeted to subgroups where these discoveries can have the greatest impact.
WFPC2 11156
Monitoring Active Atmospheres on Uranus and Neptune
We propose Snapshot observations of Uranus and Neptune to monitor changes in their atmospheres on time scales of weeks and months. Uranus equinox is only months away, in December 2007. Hubble Space Telescope observations during the past several years {Hammel et al. 2005, Icarus 175, 284 and references therein} have revealed strongly wavelength- dependent latitudinal structure, the presence of numerous visible-wavelength cloud features in the northern hemisphere, at least one very long-lived discrete cloud in the southern hemisphere, and in 2006 the first dark spot ever seen on Uranus. Long-term ground-based observations {Lockwood and Jerzekiewicz, 2006, Icarus 180, 442; Hammel and Lockwood 2007, Icarus 186, 291} reveal seasonal brightness changes whose origins are not well understood. Recent near- IR images of Neptune obtained using adaptive optics on the Keck Telescope, together with HST observations {Sromovsky et al. 2003, Icarus 163, 256 and references therein} which include previous Snapshot programs {GO 8634, 10170, 10534} show a general increase in activity at south temperate latitudes until 2004, when Neptune returned to a rather Voyager-like appearance. Further Snapshot observations of these two dynamic planets will elucidate the nature of long-term changes in their zonal atmospheric bands and clarify the processes of formation, evolution, and dissipation of discrete albedo features.
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.
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 07 07
FGS REacq 07 07
OBAD with Maneuver 28 28
SIGNIFICANT EVENTS: (None)
