Status Report

NASA Hubble Space Telescope Daily Report #4067

By SpaceRef Editor
March 10, 2006
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NASA Hubble Space Telescope Daily Report #4067

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT March 09, 2006 (DOY 068)


ACS/HRC 10525

Characterizing the Near-UV Environment of M Dwarfs: Implications for Extrasolar Planetary Searches and Astrobiology

We propose SNAP observations with the ACS HRC PR200L prism, designed to measure the near ultraviolet emission in a sample of 107 nearby M dwarfs. The sample spans the mass range from 0.1 – 0.6 solar masses {temperature range 2200K – 4000K} where the UV energy distributions vary widely between active and inactive stars. The strength and distribution of this UV emission can have critical consequences for the atmospheres of attendant planets. Our proposed observations will provide desperately needed constraints on models of the habitability zone and the atmospheres of possible terrestrial planets orbiting M dwarf hosts, and will be used to sharpen TPF target selection. In addition, the NUV data will be used in conjunction with existing optical, FUV and X-ray data to constrain a new generation of M dwarf atmospheric models, and to explore unanswered questions regarding the dynamo generation and magnetic heating in these low-mass stars.

ACS/WFC 10181

ACS/NICMOS Imaging of Bright Lyman Break Galaxy Candidates from SDSS

The recent surprising discovery of six unusually bright {r~20 mag} Lyman break galaxy {LBG} candidates with z=2.45-2.80 in the Sloan Digital Sky Survey {SDSS} raises a number of questions that only HST can address. Specifically, what is the true nature of these objects, and what role if any is played by gravitational lensing? We propose to use the superior resolution and sensitivity of ACS and NICMOS to obtain deep images of these objects and their environments. Compared to SDSS images, HST will allow us to determine their morphologies {extended, point-source, or lensed}, the appearance of their environments {rich or poor}, and to detect any faint foreground groups or clusters that might be responsible for lensing these objects. All outcomes would be intriguing. If the objects are lensed, it increases from 1 {MS1512- cB58} to 7 the number of normal LBGs bright enough to study individually. If they are instead unlensed point sources, they will represent a new class of previously unidentified absorption- line quasars. Finally, if they are unlensed and extended star-forming galaxies, they are at least 4mag brighter than L_* LBGs, thus making them the most luminous star-forming objects yet seen, representing a heretofore unknown extreme population of objects.

ACS/WFC 10626

A Snapshot Survey of Brightest Cluster Galaxies and Strong Lensing to z = 0.9

We propose an ACS/WFC snapshot survey of the cores of 150 rich galaxy clusters at 0.3 < z < 0.9 from the Red Sequence Cluster Survey {RCS}. An examination of the galaxian light in the brightest cluster galaxies, coupled with a statistical analysis of the strong-lensing properties of the sample, will allow us to contrain the evolution of both the baryonic and dark mass in cluster cores, over an unprecedented redshift range and sample size. In detail, we will use the high- resolution ACS images to measure the metric {10 kpc/h} luminosity and morphological disturbances around the brightest clusters galaxies, in order to calibrate their accretion history in comparison to recent detailed simulations of structure formation in cluster cores. These images will also yield a well-defined sample of arcs formed by strong lensing by these clusters; the frequency and detailed distribution {size, multiplicity, redshifts} of these strong lens systems sets strong constraints on the total mass content {and its structure} in the centers of the clusters. These data will also be invaluable in the study of the morphological evolution and properties of cluster galaxies over a significant redshift range. These analyses will be supported by extensive ongoing optical and near-infrared imaging, and optical spectroscopy at Magellan, VLT and Gemini telescopes, as well as host of smaller facilities.

FGS 10610

Astrometric Masses of Extrasolar Planets and Brown Dwarfs

We propose observations with HST/FGS to estimate the astrometric elements {perturbation orbit semi-major axis and inclination} of extra-solar planets orbiting six stars. These companions were originally detected by radial velocity techniques. We have demonstrated that FGS astrometry of even a short segment of reflex motion, when combined with extensive radial velocity information, can yield useful inclination information {McArthur et al. 2004}, allowing us to determine companion masses. Extrasolar planet masses assist in two ongoing research frontiers. First, they provide useful boundary conditions for models of planetary formation and evolution of planetary systems. Second, knowing that a star in fact has a plantary mass companion, increases the value of that system to future extrasolar planet observation missions such as SIM PlanetQuest, TPF, and GAIA.

NIC1/NIC2/NIC3/NIC 10466

The Galactic Bulge Deep Field: A Planetary Transit Survey and Very Deep Stellar Mass Function

We propose to observe a Galactic bulge field continuously with ACS/WFC over a 7-day period. We will monitor ~167, 000 F, G, and K dwarfs down to V=23, in order to detect transits by orbiting Jovian planets. If the frequency of “hot Jupiters” is similar to that in the solar neighborhood, we will detect over 100 planets, more than doubling the number of extrasolar planets known. For the brighter stars with transits, we will confirm the planetary nature of the companions through radial- velocity measurements using the 8-m VLT. We will determine the metallicities of most of the planet-bearing stars as well as a control sample, through follow-up VLT spectroscopy. The metallicities of the target stars range over more than 1.5 dex, allowing for a determination of the dependence of planet frequency upon metallicity–a crucial element in understanding planet formation. We will be able to discriminate between the equally numerous disk and bulge stars via proper motions. Hence we will determine, for the first time, the frequencies of planets in two entirely different stellar populations. We will also determine for the first time the distribution of planetary radii for extrasolar planets for both these populations. Parallel observations with NICMOS will provide ultra-deep near-infrared images of a nearby bulge field, which will be used to determine the stellar luminosity and mass functions down to the brown-dwarf regime. The data will also be useful for a variety of spinoff projects, including a census of variable stars and of hot white dwarfs in the bulge, and the metallicity distribution of bulge dwarfs.


Kinematics and morphology of the most massive field disk galaxies at z>1

We propose to obtain 1 orbit NIC-2 images of a sample of the 15 most massive galaxies found at $1 < z < 1.3$. These were culled from over 20, 000 Keck spectra collected as part of DEEP and are unique among high redshift massive galaxy samples in being kinematically selected. We intend to test whether these potentially very young galaxies are likely precursors to massive local disks, assuming no further merging. NIC-2 images provide rest-frame optical morphologies that will show whether they are normal disky systems or instead more disturbed looking objects with multiple subcomponents, mergers, peculiar structure, etc. NIC-2 provides near-IR resolutions sufficient to enable measurements of bulges and disks subcomponents. The near-IR will fill a critical gap in the broad-band SED photometry of the galaxy and its subcomponents to estimate mean stellar ages and stellar masses and to assess whether old stellar bulges and disks are in place at that time. Finally, this sample will yield the first statistically significant results on the $z > 1$ evolution of the Tully-Fisher relation for massive galaxies. In addition, we propose parallel observations with ACS WFC {V and I bands} and WFPC2 {I-band}. These will target up to 700 galaxies at redshifts 0.7 … 1.2 for which the DEEP2 survey has obtained precision redshifts and high-resolution kinematic data. The added HST morphology and color information will allow a variety of detailed studies on dynamical, structural, and photometric evolution of galaxies.

WFPC2 10492

A detailed study of the mass properties for the galaxy cluster RX J1347-1145

We propose to obtain deep, multi-colour imaging for the galaxy cluster RX J1347-1145 at z=0.45. Together with our high-quality ground-based optical and X-ray data sets already at hand this observation will produce a precise mass determination of this most X-ray luminous cluster. The analysis will mainly be carried out by a newly developed and novel technique that combines weak and strong lensing information and which is able to break the mass-sheet degeneracy that hampered most previous lensing mass determinations. Within our extensive campaign to understand the mass properties of RX J1347-1145, the main goal of the ACS images will be a refined, high-resolution lensing mass reconstruction of the cluster core. This will be achieved by a substantially increased number density of background sources for a weak lensing analysis in combination with constraints from multiply lensed images that are identified with morphology and colour information. Both of these require the unique resolving power of ACS. RX J1347-1145 is an ideal candidate for elucidating the discrepant mass estimates obtained from traditional methods. It plays the same role at high redshift as A1689 at intermediate redshifts for which a similar analysis has been performed with ACS. Our results will therefore be an important ingredient in the use of galaxy clusters as cosmological probes.

WFPC2 10779

WFPC2 WF4 Temperature Reduction Test #2

The WF4 CCD bias level appears to have become unstable, resulting in sporadic images with either low or zero bias level. The other three CCDs {PC1, WF2, and WF3} appear to be unaffected and continue to operate properly. This is a second test to further reduce temperatures. Orbits: internal 26, external 1


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

HSTARS: (None)



                        SCHEDULED      SUCCESSFUL
FGS GSacq               07                   07
FGS REacq               08                   08
OBAD with Maneuver  28                   28


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