NASA Hubble Space Telescope Daily Status Report #4107

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT # 4107

PERIOD COVERED: UT May 04, 2006 (DOY 124)

OBSERVATIONS SCHEDULED

ACS/HRC/WFC 10514

Kuiper Belt Binaries: Probes of Early Solar System Evolution

Binaries in the Kuiper Belt are a scientific windfall: in them we have relatively fragile test particles which can be used as tracers of the early dynamical evolution of the outer Solar System. We propose a Snapshot program using the ACS/HRC that has a potential discovery efficiency an order of magnitude higher than the HST observations that have already discovered the majority of known transneptunian binaries. By more than doubling the number of observed objects in dynamically hot and cold subpopulations we will be able to answer, with statistical significance, the question of whether these groups differ in the abundance of binaries as a result of their particular dynamical paths into the Kuiper Belt. Today’s Kuiper Belt bears the imprints of the final stages of giant-planet building and migration; binaries may offer some of the best preserved evidence of that long-ago era.

ACS/WFC 10496

Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters

We propose a novel HST approach to obtain a dramatically more useful “dust free” Type Ia supernovae {SNe Ia} dataset than available with the previous GOODS searches. Moreover, this approach provides a strikingly more efficient search-and-follow-up that is primarily pre- scheduled. The resulting dark energy measurements do not share the major systematic uncertainty at these redshifts, that of the extinction correction with a prior. By targeting massive galaxy clusters at z > 1 we obtain a five-times higher efficiency in detection of Type Ia supernovae in ellipticals, providing a well-understood host galaxy environment. These same deep cluster images then also yield fundamental calibrations required for future weak lensing and Sunyaev-Zel’dovich measurements of dark energy, as well as an entire program of cluster studies. The data will make possible a factor of two improvement on supernova constraints on dark energy time variation, and much larger improvement in systematic uncertainty. They will provide both a cluster dataset and a SN Ia dataset that will be a longstanding scientific resource.

ACS/WFC 10503

The Star Formation Histories of Early Type Dwarf Galaxies in Low Density Environments: Clues from the Sculptor Group

We seek HST ACS/WFC time to conduct a detailed study of the stellar populations of 5 early-type {dE, dE/dIrr} dwarf galaxies in the nearby {~1.5 to 4 Mpc} Sculptor group. Four of these systems have been recently found to contain modest amounts of HI, and existing ground-based and HST snapshot data point to the potential presence of small populations of young {blue} stars in at least three of these systems. Consequently, they resemble the Local Group ‘transition’ objects Phoenix and LGS3. The relative number of such transition systems is thus substantially larger in the low density environment of the Scl group than for the Local Group. Detailed stellar populations studies will allow estimation of the star formation histories, via stellar population modelling of the color-magnitude diagrams, of the target dwarfs, which in turn will connect to gas consumption and retention rates. For the two nearer dwarfs we aim to reach below the horizontal branch {a first for any system beyond the Local Group} equivalent to a main sequence turnoff age of ~1 Gyr. The observations of these two systems will also allow detection of RR Lyrae variables and thus direct confirmation of the presence of old populations. For the other three dwarfs will we cover the first 2.5 mags of the red giant branch, equivalent to the main sequence termination for a ~300 Myr population. The results will have implications for theories of galaxy formation and evolution, particularly with regard to the evolutionary relation between low luminosity dEs and dwarf irregulars.

ACS/WFC 10592

An ACS Survey of a Complete Sample of Luminous Infrared Galaxies in the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared selected galaxies exceeds that of optically selected galaxies. These `luminous infrared galaxies’ {LIRGs} are primarily interacting or merging disk galaxies undergoing enhanced star formation and Active Galactic Nuclei {AGN} activity, possibly triggered as the objects transform into massive S0 and elliptical merger remnants. We propose ACS/WFC imaging of a complete sample of 88 L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised Bright Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}. This sample is ideal not only in its completeness and sample size, but also in the proximity and brightness of the galaxies. The superb sensitivity, resolution, and field of view of ACS/WFC on HST enables a unique opportunity to study the detailed structure of galaxies that sample all stages of the merger process. Imaging will be done with the F439W and F814W filters {B and I-band} to examine as a function of both luminosity and merger state {i} the evidence at optical wavelengths of star formation and AGN activity and the manner in which instabilities {bars and bridges} in the galaxies may funnel material to these active regions, {ii} the relationship between star formation and AGN activity, and {iii} the structural properties {AGN, bulge, and disk components} and fundamental parameters {effective radius and surface brightness} of LIRGs and their similarity with putative evolutionary byproducts {elliptical, S0 and classical AGN host galaxies}. This HST survey will also bridge the wavelength gap between a Spitzer imaging survey {covering seven bands in the 3.6-160 micron range} and a GALEX UV imaging survey of these galaxies, but will resolve complexes of star clusters and multiple nuclei at resolutions well beyond the capabilities of either Spitzer or GALEX. The combined datasets will result in the most comprehensive multiwavelength study of interacting and merging galaxies to date.

ACS/WFC/HRC 10536

What Are Stalled Preplanetary Nebulae? An ACS SNAPshot Survey

Essentially all planetary nebulae {PNs} are aspherical, whereas the mass-loss envelopes of AGB stars are strikingly spherical. Our previous SNAPshot surveys of a morphologically unbiased sample of pre-planetary nebulae {PPNs} — objects in transition between the AGB and PN evolutionary phases — show that roughly half our observed targets are resolved, with bipolar or multipolar morphologies. Spectroscopic observations of our sample confirm that these objects have not yet evolved into planetary nebulae. Thus, the transformation from spherical to aspherical geometries has already fully developed by the time these dying stars have become PPNs. Although our current studies have yielded exciting results, they are limited in two important ways — {1} the number of well-resolved objects is still small {18}, and the variety of morphologies observed relatively multitudinous, hence no clear trends can yet be established between morphology and other source properties {e.g., near-IR, far-IR colors, stellar spectral type, envelope mass}, and {2} the current samples are strongly biased towards small PPNs, as inferred from their low 60-to-25 micron flux ratios [R{60/25}<1]. However, the prototype of objects with R{60/25}>1, the Frosty Leo Nebula, has a puzzlingly large post-AGB age {almost 10^4 yr} and a fairly cool central star, very different from the expectations of single-star stellar evolutionary models. A proposed, but still speculative, hypothesis for such objects is that the slow evolution of the central star is due to backflow of material onto the mass-losing star, retarding its evolution towards the PN phase. This hypothesis has significant consequences for both stellar and nebular evolution. We therefore propose a survey of PPNs with R{60/25}>1 which is heavily weighted towards the discovery of such “stalled PPNs”. Supporting kinematic observations using long-slit optical spectroscopy {with the Keck}, millimeter and radio interferometric observations {with OVRO, VLA & VLBA} are being undertaken. The results from this survey {together with our previous work} will allow us to draw general conclusions about the complex mass-outflow processes affecting late stellar evolution, and will provide crucial input for theories of post-AGB stellar evolution. Our survey will produce an archival legacy of long-standing value for future studies of dying stars.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10250 – OBAD Caused Inadvertent 10deg Maneuver @ 034/15:58:50z An OBAD map/maneruver incorrectly identified a 10 deg attitude error and maneuvered the spacecraft thus injecting a 10deg attitude error. The subsequent OBAD correctly identified the error from the first OBAD and maneuvered the spacecraft back to the correct attitude. The sebsequent FGS acquisition was succesfull.

COMPLETED OPS REQUEST:

17747-1 – Battery 2 Capacity Test Script & 5 Battery Pressure Limit COP (thru step 34) @ 124/2112z

17746-0 – Continuous Engineering Recording for Battery # 2 BCT @ Record 124/0944-1034z, Rewind 124/1050z, Record 124/1519-1622z, Record 124/1655-1756z, Rewind/TRINIT/Power off @ 124/1904z

17750-0 – CONTINGENCY: Disable ROC test for Battery 2 capacity test @ DISABLE 124/1141z, ENABLE 124/1751z

COMPLETED OPS NOTES: (None)

                          SCHEDULED      SUCCESSFUL
FGS 
GSacq                06                     06 

FGS 
REacq                08                     08 

OBAD with Maneuver   30                     30

SIGNIFICANT EVENTS:

FLASH REPORT

(Thu, 4 May 2006 05:37:57, GWaldo) — “Battery 2 Low-Rate Discharge Termination” — Battery 2 Capacity Test Flash Report — Battery 2 low-rate discharge was completed on Thursday morning. Following approximately 43 hours of total discharge time, the target low voltage was reached and the reconditioning resistor was autonomously turned off by HST486 FSW at 124/0844 GMT. EPS hardware reconfiguration was completed during the orbit night period, with the reconnection of solar array section 2 to battery 2 occurring at 124/0848 GMT.

FLASH REPORT

(Fri, 05 May 2006 00:26:38, EPS SE) – “Battery 2 Flash Report” — Following placing Battery 2 back on-line in hardware at 124/0848 GMT, the first Elevated VTFE – two orbit Boost was performed at 124/1151 GMT. The boost was autonomously terminated at 124/1503 GMT. Following the completion of the first boost cycle, the battery temperatures remained less than 5.3DegC. The second Elevated VTFE Boost was performed at 124/1759 and autonomously terminated at 124/2113 GMT. Battery temperatures increased ~2 DegC with battery 6 temperature reaching 6.85 DegC. As of 125/0020, the battery temperatures were continuing to trend downward with battery 5 the highest at 4.26 DegC. EPS SEs are scheduled to place battery back on-line in hardware at ~125/1630 GMT (Friday, May 5th 12:30pm local).

Intercept SMS for target of opportunity (Proposal # 10624 – “Solving the Mystery of the Short-Hard Gamma-Ray Bursts”), command loader SA121Q03_F1, authorized @ 124/22:59:47z