Status Report

NASA Hubble Space Telescope Daily Report #4678

By SpaceRef Editor
August 20, 2008
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Continuing to collect World Class Science

PERIOD COVERED: 5am August 19 – 5am August 20, 2008 (DOY 232/0900z-233/0900z)


NIC1 11205

The Effects of Multiplicity on the Evolution of Young Stellar Objects: A NICMOS Imaging Study

We propose to use NICMOS to investigate the multiplicity of young stellar objects (YSOs) in the Orion B molecular cloud. Previous observations with the Spitzer Space Telescope have revealed a remarkable star forming filament near the NGC 2068 reflection nebula. The population of YSOs associated with the filament exhibit a surprisingly wide range of circumstellar evolutionary states, from deeply embedded protostars to T Tauri accretion disks. Many of the circumstellar disks themselves show evidence for significant dust evolution, including grain growth and settling and cleared inner holes, apparently in spite of the very young age of these stars. We will estimate the binary fraction of a representative sample of objects in these various stages of evolution in order to test whether companions may play a significant role in that evolution.

NIC1/NIC2/NIC3 11330

NICMOS Cycle 16 Extended Dark

This takes a series of Darks in parallel to other instruments.

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 11548

NICMOS Imaging of Protostars in the Orion A Cloud: The Role of Environment in Star Formation

We propose NICMOS observations of a sample of 252 protostars identified in the Orion A cloud with the Spitzer Space Telescope. These observations will image the scattered light escaping the protostellar envelopes, providing information on the shapes of outflow cavities, the inclinations of the protostars, and the overall morphologies of the envelopes. In addition, we ask for Spitzer time to obtain 55-95 micron spectra of 75 of the protostars. Combining these new data with existing 3.6 to 70 micron photometry and forthcoming 5-40 micron spectra measured with the Spitzer Space Telescope, we will determine the physical properties of the protostars such as envelope density, luminosity, infall rate, and outflow cavity opening angle. By examining how these properties vary with stellar density (i.e. clusters vs groups vs isolation) and the properties of the surrounding molecular cloud; we can directly measure how the surrounding environment influences protostellar evolution, and consequently, the formation of stars and planetary systems. Ultimately, this data will guide the development of a theory of protostellar evolution.

WFPC2 11130

AGNs with Intermediate-mass Black Holes: Testing the Black Hole-Bulge Paradigm, Part II

The recent progress in the study of central black holes in galactic nuclei has led to a general consensus that supermassive {10^6-10^9 solar mass} black holes are closely connected with the formation and evolutionary history of large galaxies, especially their bulge component. Two outstanding issues, however, remain unresolved. Can central black holes form in the absence of a bulge? And does the mass function of central black holes extend below 10^6 solar masses? Intermediate-mass black holes {<10^6 solar masses}, if they exist, may offer important clues to the nature of the seeds of supermassive black holes. Using the SDSS, our group has successfully uncovered a new population of AGNs with intermediate-mass black holes that reside in low-luminosity galaxies. However, very little is known about the detailed morphologies or structural parameters of the host galaxies themselves, including the crucial question of whether they have bulges or not. Surprisingly, the majority of the targets of our Cycle 14 pilot program have structural properties similar to dwarf elliptical galaxies. The statistics from this initial study, however, are really too sparse to reach definitive conclusions on this important new class of black holes. We wish to extend this study to a larger sample, by using the Snapshot mode to obtain WFPC2 F814W images from a parent sample of 175 AGNs with intermediate- mass black holes selected from our final SDSS search. We are particularly keen to determine whether the hosts contain bulges, and if so, how the fundamental plane properties of the host depend on the mass of their central black holes. We will also investigate the environment of this unique class of AGNs.

WFPC2 11221

A Dark Core in Abell 520

We have recently disocovered that the rich cluster Abell 520 exhibits truly extreme multi-wavelength characteristics. The data indicate that the cluster is the site of a major merger. Our weak lensing analysis, based on a deep CFHT image, suggests the presence of a massive dark core that coincides with the central X-ray emission peak, while being largely devoid of galaxies. Although a displacement between the X-ray gas and the galaxy/dark matter distribution may be expected in a merger (e.g. as in the bullet cluster), the dark matter peak without galaxies cannot be easily explained within the current collisionless dark matter paradigm. A higher resolution mass map is required to make further progress, as it will enable us to examine the detailed structure of the dark matter distribution, as well as improve the significance of the dark peak. We propose a 3 x 3 WFPC2 mosaic of interlaced images, where each pointing consists of two sets of F814W exposures offset by 5.5 pixels. This will precisely pinpoint the locations of the highest lensing peaks, enhance the comparison with the Chandra X-ray data, and test physical and geometrical models for the spatial and thermal structure of this remarkable cluster derived from our suite of gas+dark matter simulations of head-on/off-axis cluster mergers.


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


11449 – GSacq(2,1,1) failed to RGA control

At 232/23:58:32 the GSacq(2,1,1) scheduled at 232/23:55:35 failed to RGA control due to scan step limit exceeded on FGS 2.

Observations affected: NIC 86 – 107 Proposal ID 11512



                        SCHEDULED      SUCCESSFUL

FGS GSacq               08                  07
FGS REacq               07                  07
OBAD with Maneuver      30                  30


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