Status Report

NASA Hubble Space Telescope Daily Report #4804

By SpaceRef Editor
March 8, 2009
Filed under , ,


Continuing to collect World Class Science

PERIOD COVERED: 5am March 4 – 5am March 5, 2009 (DOY 063/1000z-064/1000z)


ACS/SBC 11982

Spanning the Reionization History of IGM Helium: a Large and Efficient HST Spectral Survey of Far-UV-Bright Quasars

The reionization of IGM helium is thought to have occurred at redshifts of z=3 to 4. Detailed studies of HeII Lyman-alpha absorption toward a handful of QSOs at 2.72.8 SDSS DR7 (and other) quasars with GALEX GR4 UV sources to obtain 550 new, high confidence, sightlines potentially useful for HST HeII studies; and in cycle 15-16 trials we demonstrated the efficacy of our SDSS/GALEX selection approach identifying 9 new HeII quasars at unprecedented 67% efficiency. We propose the first far-UV-bright HeII quasar survey that is both large in scale and also efficient, via 2-orbit reconnaissance ACS/SBC prism spectra toward a highly select subset of 40 new SDSS/GALEX quasars at 3.14), enabling superb post-SM4 follow-up spectra with COS or STIS. But simultaneously and independent of any SM4 uncertainties, we will hereby directly obtain 10-orbit UV spectral stacks from the 5 HeII quasars in each of the 8 redshift bins to trace the reionization history of IGM helium over at least 3.1

FGS 11788

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.

FGS 11943

Binaries at the Extremes of the H-R Diagram

We propose to use HST/Fine Guidance Sensor 1r to survey for binaries among some of the most massive, least massive, and oldest stars in our part of the Galaxy. FGS allows us to spatially resolve binary systems that are too faint for ground-based, speckle or optical long baseline interferometry, and too close to resolve with AO. We propose a SNAP-style program of single orbit FGS TRANS mode observations of very massive stars in the cluster NGC 3603, luminous blue variables, nearby low mass main sequence stars, cool subdwarf stars, and white dwarfs. These observations will help us to (1) identify systems suitable for follow up studies for mass determination, (2) study the role of binaries in stellar birth and in advanced evolutionary states, (3) explore the fundamental properties of stars near the main sequence-brown dwarf boundary, (4) understand the role of binaries for X-ray bright systems, (5) find binaries among ancient and nearby subdwarf stars, and (6) help calibrate the white dwarf mass – radius relation.

WFPC2 11978

Luminous and Dark Matter in Disk Galaxies from Strong Lensing and Stellar Kinematics

The formation of realistic disk galaxies within the LCDM paradigm is still an unsolved problem. Theory is only 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, from an observational point of view, the degeneracy between the stellar and dark matter contributions to galaxy rotation curves remains a major road block. Strong gravitational lensing, when coupled to spatially-resolved kinematics and stellar population models, can solve this long-standing problem. Unfortunately, this joint methodology could not be exploited so far due to the paucity of known edge-on spiral lenses. Exploiting the full SDSS-DR7 archive we have identified a new sample of exactly these systems. We propose multi-color HST imaging to confirm and measure a sample of twenty spiral lenses, covering a range of bulge to disk ratios. By combining dynamical lensing and stellar population information for this unique sample we will deliver the first statistical constraints on halos and disk properties, and a new stringent test of disk galaxy formation theories.

WFPC2 11983

An Imaging Survey of Protoplanetary Disks and Brown Dwarfs in the Chamaeleon I region

We propose to carry out a HST/WFPC2 survey of young brown dwarfs, Class I and Class II sources in the Chamaelon I region, one of the best-studied star-forming regions, in order to investigate the link between disk evolution and the formation of substellar-mass objects. We will use deep broad-band imaging in the I and z-equivalent HST bands to unveil the unknown population of substellar binary companions, down to a few Jupiter masses for separations of a few tens of AU. We will also perform narrow-band imaging to directly detect accreting circumstellar disks and jets around brown dwarfs, Class-I and class-II objects. Chamaelon I is nearly coeaval of Orion (~1-2Myr) but at ~1/3 its distance, allowing 3x higher resolution and 10x more flux for comparable objects. Unlike Orion, low-mass objects and protoplanetary disks in Chamaeleon I have been extensively studied with Spitzer, but not yet with the HST. The Chamaeleon I region is an ideal HST target, as it lies in the CVZ of the HST and therefore it is easily accessible any time of the year with long orbits.


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


11706 – GSAcq (1,2,1) at 063/18:28:56 failed with QF1STOPF and QSTOP flags set.

Observations affected: WFPC 166 – 181, Proposal ID#11983.



                        SCHEDULED      SUCCESSFUL

FGS GSAcq               08                  07
FGS REAcq               07                  07
OBAD with Maneuver      26                  26


SpaceRef staff editor.