Status Report

NASA Hubble Space Telescope Daily Report #4691

By SpaceRef Editor
September 9, 2008
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Continuing to collect World Class Science

PERIOD COVERED: 5am September 8 – 5am September 9, 2008 (DOY 252/0900z-253/0900z)


NIC1/NIC2 11818

NICMOS Confirmation of an Extrasolar Panet Candidate Directly Detected with ACS

With ACS/HRC coronagraphy, we have achieved the direct detection of a planet candidate in F606W and F814W around a bright nearby star with a debris belt. The planet candidate lies 18 astronomical units interior to the dust belt and we detect counterclockwise orbital motion in observations separated by 1.75 years. The candidate has mass no greater than three Jupiter masses based on an analysis of its luminosity and the dynamical argument that a significantly more massive object would disrupt the dust belt. Using recent model predictions for 100-300 Myr old planetary atmospheres, the planet candidate has a temperature of ~400 K and a mass 1.6 – 3.4 M_J. Variability at optical wavelengths suggests additional sources of luminosity such as H-alpha emission or the episodic accretion of cometary material. A key surprise is that the planet candidate is NOT detected in Keck adaptive optics observations at 1.6 microns. Two model atmospheres predict a flux a few times greater than our detection limit, though the model predictions disagree with each other by a factor of five due to theoretical uncertainty in the strength of CH4 vibrational bands. These models predict the strongest emission centered on the F110W passband of NICMOS such that the F814W – F110W color will be red. Here we propose follow-up NICMOS observations to verify that the emission observed in F814W is due to the emergent flux from passive cooling of the planet, as opposed to other explanations, such as reflected light from a Saturn analog with a circumplanetary debris disk that would produce a bluer F814W – F110W color. Additional deep images in and and out of the 1.14 micron water trough using NIC1 narrowband filters will test whether or not the emission is produced from the passive cooling of a young massive planet.

NIC1/NIC2/NIC3 11820

NICMOS Post-SAA Calibration – CR Persistence Part 7

Internals for CR persistence

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 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 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 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 11291

Following Eta Carinae’s Change of State

Eta Carinae is now known to be undergoing some unusually rapid changes on a timescale of several years. They are probably essential for modeling the star’s long-term recovery from its Giant Eruption 160 years ago — the prototype “supernova impostor” event. Since high spatial resolution is needed to isolate the central star, and the present state will probably not recur in the future, it is important to obtain HST data during the next two years. We propose a cost- effective set of ACS observations with three goals: {1} to obtain a continuing record of the star’s rapid UV and visual brightening; {2} to lengthen the temporal baseline of ACS images enough to settle an important question concerning ejecta ages; and {3} to extend the record of morphological changes in the inner ejecta past the midpoint of eta Car’s 5.5-year cycle.

WFPC2 11302

WFPC2 CYCLE 16 Standard Darks – Part III

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 11793

WFPC2 Cycle 16 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.


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

HSTARS: (None)



                         SCHEDULED      SUCCESSFUL

FGS GSacq                 13                  13
FGS REacq                 01                  01
OBAD with Maneuver        28                  28


SpaceRef staff editor.