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Daily Report #4514
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT****** # 4514 PERIOD COVERED: UT December 26, 2007 (DOY 360) OBSERVATIONS SCHEDULED ACS/SBC 11145 Probing the Planet Forming Region of T Tauri Stars in Chamaeleon By studying the inner, planet-forming regions of circumstellar disks around low-mass pre- main sequence stars we can refine theories of giant planet formation and develop timescales for the evolution of disks and their planets. Spitzer infrared observations of T Tauri stars in the Chamaeleon star-forming region have given us an unprecedented look at dust evolution in young objects. However, despite this ground breaking progress in studying the dust in young disks, the gas properties of the inner disk remain essentially unknown. Using ACS on HST, we propose to measure the H_2 emission originating in the innermost disk regions of classical T Tauri stars in different stages of evolution with the objective of revealing the timescales of gas dissipation and its relationship to dust evolution. This proposal is part of a comprehensive effort with approved programs on Spitzer, Gemini, and Magellan that aim to characterize the state of gas and dust in disks where planets may already have formed. FGS 11210 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. 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. WFPC2 11040 Geometric Distortion / Astrometry Closeout These observations will serve as a final characterization of the geometric distortion and astrometric calibration. The Omega-Cen inner calibration field is used. Filters F300W, F555W, and F814W are observed at 5 roll angles spanning 180 degrees; F218W is observed at a single roll angle. WFPC2 11083 The Structure, Formation and Evolution of Galactic Cores and Nuclei A surprising result has emerged from the ACS Virgo Cluster Survey {ACSVCS}, a program to obtain ACS/WFC gz imaging for a large, unbiased sample of 100 early-type galaxies in the Virgo Cluster. On subarcsecond scales {i.e., 0.1"-1"}, the HST brightness profiles vary systematically from the brightest giants {which have nearly constant surface brightness cores} to the faintest dwarfs {which have compact stellar nuclei}. Remarkably, the fraction of galaxy mass contributed by the nuclei in the faint galaxies is identical to that contributed by supermassive black holes in the bright galaxies {0.2%}. These findings strongly suggest that a single mechanism is responsible for both types of Central Massive Object: most likely internally or externally modulated gas inflows that feed central black holes or lead to the formation of "nuclear star clusters". Understanding the history of gas accretion, star formation and chemical enrichment on subarcsecond scales has thus emerged as the single most pressing question in the study of nearby galactic nuclei, either active or quiescent. We propose an ambitious HST program {199 orbits} that constitutes the next, obvious step forward: high-resolution, ultraviolet {WFPC2/F255W} and infrared {NIC1/F160W} imaging for the complete ACSVCS sample. By capitalizing on HST's unique ability to provide high-resolution images with a sharp and stable PSF at UV and IR wavelengths, we will leverage the existing optical HST data to obtain the most complete picture currently possible for the history of star formation and chemical enrichment on these small scales. Equally important, this program will lead to a significant improvement in the measured structural parameters and density distributions for the stellar nuclei and the underlying galaxies, and provide a sensitive measure of "frosting" by young stars in the galaxy cores. By virtue of its superb image quality and stable PSF, NICMOS is the sole instrument capable of the IR observations proposed here. In the case of the WFPC2 observations, high-resolution UV imaging { 0.1"} is a capability unique to HST, yet one that could be lost at anytime. 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 11339 A deep observation of NGC4261: understanding its unique X-ray source population, gas morphology, and jet properties The nearby early-type galaxy NGC4261 reveals strikingly asymmetric distributions of X-ray sources as seen with Chandra, and globular clusters (GC) as seen in the optical band. To address the link between these populations based on their spatial correlation, luminosity function and spectral properties, and to investigate the possibility that this effect is due to the galaxy's merger history, we propose a 100ksec Chandra ACIS-S3 exposure, which will detect X-ray sources down to typical LMXB luminosities (Lx~5E37 erg/s), and HST-WFPC2 observations to obtain a deep census of the GC population over the whole galaxy. These data will also allow a detailed study of its complex gaseous component, and provide information on the unique two-sided X-ray jet. FLIGHT OPERATIONS SUMMARY: Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) HSTARS: 11122 - GSacq (2,3,3) resulted in Fine Lock Back-up (2,0,2) using FGS 2 At acquisition of Signal (360/19:28:15), GSAcq (2,3,3) scheduled from 360/19:23:54 - 19:31:08 had resulted in Fine Lock Back-up (2,0,2) using FGS 2. Received QF3STOPF & QSTOP flags. No 486 ESB messages were received. Pre-acquisition OBAD #1 values: V1 748.74, V2 -1591.73, V3 754.26, RSS 1913.93. Pre-acquisition OBAD #2 values: V1 6.66, V2 -1.76, V3 6.88, RSS 9.74. COMPLETED OPS REQUEST: (None) COMPLETED OPS NOTES: (None) *********************** SCHEDULED***** SUCCESSFUL FGS GSacq************** 07**************** 07 FGS REacq************** 08**************** 08 OBAD with Maneuver **** 30**************** 30 SIGNIFICANT EVENTS: (None) |
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