#1
|
|||
|
|||
Daily Report #4804
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT****** #4804 PERIOD COVERED: 5am March 4 - 5am March 5, 2009 (DOY *************************** 063/1000z-064/1000z) OBSERVATIONS SCHEDULED 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 2.7z3.3 demonstrated the high potential of such IGM probes, but the small sample size and redshift range limit confidence in cosmological inferences. The requisite unobscured sightlines to high-z are extremely rare, but we've cross-correlated 10, 000 z2.8 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 3.1z5.1. These will provide a community resource list that includes 5 far-UV-bright (restframe) HeII sightlines in each of 8 redshift bins spanning 3.1z3.9 (and perhaps several objects at z4), 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 3.1z3.9. These spectral stacks will average over cosmic variance and individual object pathology. Our new high-yield HeII sightline sample and spectral stacks, covering a large redshift range, will allow confident conclusions about the spectrum and evolution of the ionizing background, the evolution of HeII opacity, the density of IGM baryons, and the epoch of helium reionization. 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. FLIGHT OPERATIONS SUMMARY: Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) HSTARS: 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. COMPLETED OPS REQUEST: (None) COMPLETED OPS NOTES: (None) *********************** SCHEDULED***** SUCCESSFUL FGS GSAcq************** 08***************** 07 FGS REAcq************** 07***************** 07 OBAD with Maneuver **** 26***************** 26 SIGNIFICANT EVENTS: (None) |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Daily Report | Cooper, Joe | Hubble | 0 | December 22nd 08 05:17 PM |
Daily Report #4425 | Cooper, Joe | Hubble | 0 | August 14th 07 01:41 PM |
Daily Report #4408 | Pataro, Pete | Hubble | 0 | July 20th 07 03:43 PM |
Daily Report | [email protected] | Hubble | 0 | October 29th 04 04:59 PM |
HST Daily Report 131 | George Barbehenn | Hubble | 0 | May 11th 04 02:48 PM |