HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY REPORT #5178
PERIOD COVERED: 5am September 9 - 5am September 10, 2010 (DOY 252/09:00z-253/09:00z)
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
12390 - SIC&DH Safed (CU/SDF lockup) @ 252 /22:39:21z
12392 - WFC3 Suspends at 253/04:24:35
12393 - SIC&DH-2 Bus B Current Monitor Failure @ 253/03:38:50z
COMPLETED OPS REQUEST:
18901-1 - CU/SDF Lock-up Recovery, Part B @ 253/04:19:40z
18903-0 - CU/SDF Lock-up Recovery, Part A @ 253/00:20:30z
18904-1 - Power off COS FUV @ 253/07:54:54z
18905-0 - Modify NSSC-1 ED Limit for M2BUSCUB @ 253/08:01:49z
HST experienced an SIC&DH CU/SDF lock-up at 252/22:39z. After verification of the signature the CU/SDF recovery began.
SWELLS: Doubling the Number of Disk-dominated Edge-on Spiral Lens Galaxies
The formation of realistic disk galaxies within the LCDM cosmology is still largely an unsolved problem. Theory is now beginning to make predictions for how dark matter halos respond to galaxy formation, and for the properties of disk galaxies. Measuring the density profiles of dark matter halos on galaxy scales is therefore a strong test for the standard paradigm of galaxy formation, offering great potential for discovery. However, the degeneracy between the stellar and dark matter contributions to galaxy rotation curves remains a major obstacle. Strong gravitational lensing, when combined with spatially resolved kinematics and stellar population models, can solve this long-standing problem. Unfortunately, this joint methodology could not be exploited until recently due to the paucity of known edge-on spiral lenses. We have developed and demonstrated an efficient technique to find exactly these systems. During supplemental cycle-16 we discovered five new spiral lens galaxies, suitable for rotation curve measurements. We propose multi-color HST imaging of 16 candidates and 2 partially-imaged confirmed systems, to measure a sample of eight new edge-on spiral lenses. This program will at least double the number of known disk-dominated systems. This is crucial for constraining the relative contribution of the disk, bulge and dark halo to the total density profile.
Physical Parameters of the Upper Atmosphere of the Extrasolar Planet HD209458b
One of the most studied extrasolar planet, HD209458b, has revealed both its lower and upper atmosphere thanks to HST and Spitzer observatories.
Through transmission spectroscopy technique, several atmospheric species were detected: NaI, HI, OI and CII. Using STIS archived transit absorption spectrum from 3000 to 8000 Angstrom, we obtained detailed constraints on the vertical profile of temperature, pressure and abundances (Sing et al 2008a, 2008b, Lecavelier et al. 2008b).
By observing in the NUV, from 2300 to 3100 Angstrom, we expect to obtain new constraints on the physical conditions and the chemical composition of the upper atmosphere: temperature/pressure profile up to very high in the atmosphere, abundance and condensation altitudes of new species, and new insight in the atmospheric escape and ionization state at the upper levels. The observation of four HD209458b transits with a single E230M setting will give access to many NUV atomic lines addressing these issues. The proposed observations will probe, for the first time, in details the atmosphere of a hot Jupiter, thus bench marking follow up studies.
CCD Dark Monitor Part 2
Monitor the darks for the STIS CCD.
CCD Bias Monitor-Part 2
Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns.
The Stellar Winds of Evolved, Braked O-Type Magnetic Oblique Rotators
Magnetic fields have recently been discovered on several massive stars, but their origin and influence on the evolution of these stars are poorly understood. Two of these objects, HD 191612 and HD 108, are of particular interest. Very recent spectropolarimetric observations have shown that they are most likely magnetic oblique rotators, like the young O star Theta1 Ori C, whose 15d periodically variable field was found somewhat earlier. However, the two new objects are much slower rotators, unusually so for O stars, with periods of 538d and 50-60yrs, respectively, and there are other indications that they are older. They provide an opportunity to study the efficiency of wind braking of magnetic O stars through angular momentum loss. We shall perform STIS high-resolution UV spectroscopy of HD 191612 and HD 108 (phase resolved for the former) to derive more complete estimates of fundamental quantities than available from optical data alone. We shall measure the mass-loss rates from the UV wind profiles, which will constrain the extreme wind confinement of these stars and establish whether the large H-alpha emission variations are wind-related or geometrical. We shall also derive more accurate ages and stellar surface properties. In turn, these results will support a more definitive discussion of the angular momentum evolution versus the ages of HD 191612 and HD 108, and of the comparison with the younger and faster Theta1 Ori C.
IR Dark Current Monitor
Analyses of ground test data showed that dark current signals are more reliably removed from science data using darks taken with the same exposure sequences as the science data, than with a single dark current image scaled by desired exposure time. Therefore, dark current images must be collected using all sample sequences that will be used in science observations. These observations will be used to monitor changes in the dark current of the WFC3-IR channel on a day-to-day basis, and to build calibration dark current ramps for each of the sample sequences to be used by Gos in Cycle 17. For each sample sequence/array size combination, a median ramp will be created and delivered to the calibration database system (CDBS).
Catching Accreting WDs Moving into Their Instability Strip(s)
Our past HST studies of the temperatures of 9 accreting, pulsating white dwarfs in cataclysmic variables show that 3 are in the normal instability strip for single white dwarfs, but the other 6 are much hotter (15, 000-16, 500K). This dual strip has been proposed to be due to mass differences in the white dwarfs related to evolutionary history and driven by the ionization of different elements in their respective driving regions. In 2007, GW Lib (the brightest and best studied of the 6 hot accreting pulsators) and V455 And (the brightest and best studied of the 3 cool accreting pulsators) underwent rare large amplitude dwarf nova outbursts (known to heat the white dwarf) and their pulsations disappeared. We propose COS observations to: a) take advantage of the unprecedented opportunity to view the change in pulsation modes due to cooling of the white dwarf envelope and b) determine the masses of the white dwarfs to test the dual strip theory. In addition, a nova that had its outburst 22 yrs ago has begun non-radial pulsations as it returns to quiescence. We will use COS to determine its temperature in relation to the instability strip for the pulsating white dwarfs in dwarf novae.
Stellar Forensics: A Post-Explosion View of the Progenitors of Core-Collapse Supernovae
Recent studies have used high spatial resolution HST observations of SN sites to identify the progenitors of core-collapse SNe on pre-explosion images. These studies have set constraints about the nature of massive stars and their evolution just prior to their explosion as SNe. Now, at late-times when the SNe have faded sufficiently, it is possible to return to the sites of these core-collapse SNe to search for clues about the nature of their progenitors. We request time to conduct deep, late-time, high-resolution imaging with ACS/HRC of the sites of six core-collapse SNe. In this program we aim to: 1) confirm our identifications, that were made with HST pre-explosion images, of the red supergiant progenitors of four Type IIP SNe (1999ev, 2003gd, 2004A and 2005cs), by observing if the objects identified as the progenitors are now missing; 2) place precise constraints on the progenitor of the Type Ic SN 2007gr by studying its host cluster; and 3) confirm our identification of an LBV-like outburst of an unstable WR star as belonging to the progenitor of a Type Ib-n core-collapse SN (2006jc), using broad and narrow-band imaging to search for emission line stars in its locality. The deep imaging will also allow to probe the stellar populations in the immediate vicinities of these SNe, that were previously obscured by the progenitors and the bright SNe. HST provides the unique combination of high-resolution optical imaging at very faint magnitudes that will facilitate this study.
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).