Status Report

NASA Hubble Space Telescope Daily Report #4967

By SpaceRef Editor
November 7, 2009
Filed under , ,


Continuing to Collect World Class Science

PERIOD COVERED: 5am November 5 – 5am November 6, 2009 (DOY 309/10:00z-310/10:00z)



COS-GTO: Studies of the HeII Reionization Epoch

Intergalactic Ly-alpha opacity suggests that H I was reionized at z ~ 6, while He II reionization was delayed to z ~ 3. Both epochs are slightly in disagreement with recent (WMAP-3) inferences from the CMB optical depth, which suggest that IGM reionization occurred at z = 10.7 (+2.7, -2.3) (Spergel et al. 2007). However, these two methods are sensitive to different ranges of ionization (neutral fractions), which allows a partially ionized IGM between z = 6-10 produced by early stars and black holes. One of the major contributions of FUSE to cosmological studies was the detection of He II Ly-alpha (Gunn-Peterson) absorption in the spectra of two AGN at redshifts z = 2.72-2.89. The He II absorption is quite patchy between redshifts z = 2.6 and 3.2 probably because the IGM is clumpy and the reionization process is affected by source fluctuations, spectra, and radiative transfer through the IGM. Observations of the He II absorption can therefore be used as diagnostics of the ionizing sources and radiative transport over large (30-50 Mpc) distances through the IGM. The ionizing radiation field appears to be softer (higher He II/H I) in the galaxy voids. These void regions may be ionized by local soft sources (dwarf starburst galaxies), or the QSO radiation may softened by escape from AGN cores and transport through denser regions in the cosmic web.With COS, we will observe the brightest He II target, HE2347-4342, a QSO with z_em = 2.885. Our goal is to obtain a G130M moderate-resolution (R = 20, 000) spectrum from 1145-1450A. Because COS has far greater throughput than either STIS or FUSE, we will be able to resolve and characterize the He II absorption lines. The region shortward of the redshifted He II (Ly-alpha) corresponds to z = 2.77-2.92, where He II exhibits patchy transmission and absorption. The ratio of He II/H I (Ly-alpha line) opacities will provide information on the ionizing radiation field (and ionizing sources) at 1 and 4 ryd. We will perform similar He II studies on three other targets, HS1700+6416, PKS1935-692, and Q0302-003.

WFC3/IR 11548

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

We propose NICMOS and WFC3/IR 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.

WFC3/IR 11202

The Structure of Early-type Galaxies: 0.1-100 Effective Radii

The structure, formation and evolution of early-type galaxies is still largely an open problem in cosmology: how does the Universe evolve from large linear scales dominated by dark matter to the highly non-linear scales of galaxies, where baryons and dark matter both play important, interacting, roles? To understand the complex physical processes involved in their formation scenario, and why they have the tight scaling relations that we observe today (e.g. the Fundamental Plane), it is critically important not only to understand their stellar structure, but also their dark-matter distribution from the smallest to the largest scales. Over the last three years the SLACS collaboration has developed a toolbox to tackle these issues in a unique and encompassing way by combining new non-parametric strong lensing techniques, stellar dynamics, and most recently weak gravitational lensing, with high-quality Hubble Space Telescope imaging and VLT/Keck spectroscopic data of early-type lens systems. This allows us to break degeneracies that are inherent to each of these techniques separately and probe the mass structure of early-type galaxies from 0.1 to 100 effective radii. The large dynamic range to which lensing is sensitive allows us both to probe the clumpy substructure of these galaxies, as well as their low-density outer haloes. These methods have convincingly been demonstrated, by our team, using smaller pilot-samples of SLACS lens systems with HST data. In this proposal, we request observing time with WFC3 and NICMOS to observe 53 strong lens systems from SLACS, to obtain complete multi-color imaging for each system. This would bring the total number of SLACS lens systems to 87 with completed HST imaging and effectively doubles the known number of galaxy-scale strong lenses. The deep HST images enable us to fully exploit our new techniques, beat down low-number statistics, and probe the structure and evolution of early- type galaxies, not only with a uniform data-set an order of magnitude larger than what is available now, but also with a fully-coherent and self-consistent methodological approach!

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K subarray biases are acquired at less frequent intervals throughout the cycle to support subarray science observations. The internals from this proposal, along with those from the anneal procedure (Proposal 11909), will be used to generate the necessary superbias and superdark reference files for the calibration pipeline (CDBS).


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



12067 – GSAcq(1,2,1) at 302/22:12:17 lost lock shortly after achieving FL-DV on FGS2.



FGS GSAcq 6 6
FGS REAcq 7 7
OBAD with Maneuver 8 8


SpaceRef staff editor.