Status Report

NASA Hubble Space Telescope Daily Report #3918

By SpaceRef Editor
August 9, 2005
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT August 05-07, 2005 (DOY 217-219)


FGS 9335

Masses of Pre-Main Sequence Binaries

We propose to continue to map the orbits of young star binaries in
the Taurus and Ophiuchus star forming regions. Our goal is to measure
their masses dynamically. This is important because there are still
no low mass young stars with reliably known masses so calculations of
their evolution to the main sequence are uncalibrated.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration – CR Persistence Part 4

A new procedure proposed to alleviate the CR-persistence problem of
NICMOS. Dark frames will be obtained immediately upon exiting the SAA
contour 23, and every time a NICMOS exposure is scheduled within 50
minutes of coming out of the SAA. The darks will be obtained in
parallel in all three NICMOS Cameras. The POST-SAA darks will be
non-standard reference files available to users with a USEAFTER
date/time mark. The keyword ‘USEAFTER=date/time’ will also be added
to the header of each POST-SAA DARK frame. The keyword must be
populated with the time, in addition to the date, because HST crosses
the SAA ~8 times per day so each POST-SAA DARK will need to have the
appropriate time specified, for users to identify the ones they need.
Both the raw and processed images will be archived as POST-SAA
DARKSs. Generally we expect that all NICMOS science/calibration
observations started within 50 minutes of leaving an SAA will need
such maps to remove the CR persistence from the science images. Each
observation will need its own CRMAP, as different SAA passages leave
different imprints on the NICMOS detectors.

ACS/HRC 10627

A Snapshot Survey of Post-AGB Objects and Proto-Planetary Nebulae

We propose an ACS/HRC snapshot survey of 50 post-AGB sources, objects
which have evolved from the AGB but may or may not become planetary
nebulae {PNe}. This survey will complement existing HST images of
proto-planetary nebulae {PPNe} and PNe in addressing circumstellar
envelope morphology as a function of: 1} the progenitor star mass; 2}
the chemical composition; and 3} evolutionary stage. We will connect
the observed diversity of nebualar shapes with the main physical and
chemical conditions characterizing post-AGB objects, to identify the
mechanism that breaks the symmetry of AGB mass loss. To our
knowledge, no previous HST projects have been specifically designed
to address this issue. From our database of 360 post-AGB candidates,
we have selected approximately 50 targets, none of which have been or
are being observed with HST, to sample different central star masses,
chemical compositions, and evolutionary stages, uniformly across the
sky. These new data will also provide important constraints to a
quantitative analysis of Spitzer Space Telescope {SST} observations
planned for a similar sample of objects. We will model the HST images
and SST spectra using our axisymmetric dust code 2-Dust, to derive
dust density distributions, pole to equator density ratios, dust
shell masses, inclination angles as well as dust composition.

ACS/HRC 10623

HST Optical Snapshot Survey of Intermediate Redshift Ultraluminous
Infrared Galaxies

Ultraluminous infrared galaxies {ULIGs} are commonly believed to be a
transitory phase in the evolution of disk galaxy mergers into QSOs.
However, a recently reported discrepancy between the morphological
and structural properties of z < 0.13 ULIGs and z = 0.12-0.25 QSOs with M{V} < -23.5 has cast doubt on their evolutionary connection. We propose an ACS snapshot survey of a sample of 39 ULIGs with z = 0.35-1.0. These galaxies are the best suited for comparison with luminous z=0.12-0.25 QSOs because {1} they are at larger lookback times than local ULIGs, and thus are likely representative of the systems that evolve into lower redshift luminous QSOs, {2} they have luminosities comparable to luminous QSOs and, {3} they are selected in a manner that biases the sample towards harboring imbedded AGN, and thus are the most likely precursors to optical QSOs. High resolution HST ACS images will allow a determination of galaxy morphology and reveal the presence of bright AGN. The 2-D profile of each galaxy will be modeled using GALFIT, with the AGN comprising one component of the fit where applicable to better characterize the underlying galaxy. Fundamental parameters {effective radius and surface brightness, and F814W-band magnitude} of the underlying galaxy will thus be measured and compared with the host galaxies of the luminous QSO sample. This imaging campaign will consume a modest amount of HST time, but will provide for the first time a statistically significant view of ULIGs at look-back times of 30-65% the age of the universe, and sufficient resolution and sensitivity to conduct a meaningful comparison with z=0.12-0.25 QSOs, as well as with local {z < 0.3} IRAS- detected and distant {z > 2}
SCUBA-detected ULIGs.

ACS/WFC 10588

The Host Galaxies of Post-Starburst Quasars

We propose to use ACS to conduct a snapshot imaging survey of
post-starburst quasars now being discovered in signficant numbers by
the Sloan Digital Sky Survey. Post-starburst quasars are broad-lined
AGN that also possess Balmer jumps and high-n Balmer absorption lines
indicative of luminous stellar populations on order of 100 Myr old.
These objects, representing a few percent of the z < 0.5 quasar population, may be an evolutionary stage in the transition of ultraluminous infrared galaxies into normal quasars, or a type of galaxy interaction that triggers both star formation and nuclear activity. These sources may also illustrate how black hole mass/bulge mass correlations arise. Ground-based imaging of individual poststarburst quasars has revealed merger remnants, binary systems, and single point sources. Our ACS snapshots will enable us to determine morphologies and binary structure on sub-arcsecond scales {surely present in the sample and impossible to do without HST}, as well as basic host galaxy properties. We will be looking for relationships among morphology, particularly separation of double nuclei, the starburst age, the quasar black hole mass and accretion rate, that will lead to an understanding of the triggering activity and mutual evolution. This project will bring quantitative data and statistics to the previously fuzzy and anecdotal topic of the "AGN- starburst connection" and help test the idea that post-starburst quasars are an early evolutionary stage of normal quasars.

ACS/WFC 10587

Measuring the Mass Dependence of Early-Type Galaxy Structure

We propose two-color ACS-WFC Snapshot observations of a sample of 118
candidate early-type gravitational lens galaxies. Our lens-candidate
sample is selected to yield {in combination with earlier results} an
approximately uniform final distribution of 40 early- type strong
lenses across a wide range of masses, with velocity dispersions {a
dynamical proxy for mass} ranging from 125 to 300 km/s. The proposed
program will deliver the first significant sample of low-mass
gravitational lenses. All of our candidates have known lens and
source redshifts from Sloan Digital Sky Survey data, and all are
bright enough to permit detailed photometric and stellar-dynamical
observation. We will constrain the luminous and dark-matter mass
profiles of confirmed lenses using lensed- image geometry and
lens-galaxy structural/photometric measurements from HST imaging in
combination with dynamical measurements from spatially resolved
ground- based follow-up spectroscopy. Hence we will determine, in
unprecedented detail, the dependence of early-type galaxy mass
structure and mass-to-light ratio upon galaxy mass. These results
will allow us to directly test theoretical predictions for halo
concentration and star-formation efficiency as a function of mass and
for the existence of a cuspy inner dark-matter component, and will
illuminate the structural explanation behind the fundamental plane of
early-type galaxies. The lens-candidate selection and confirmation
strategy that we propose has been proven successful for high-mass
galaxies by our Cycle 13 Snapshot program {10174}. The program that
we propose here will produce a complementary and unprecedented lens
sample spanning a wide range of lens-galaxy masses.

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 10497

Cepheid Calibrations of the Luminosity of Two Reliable Type Ia
Supernovae and a Re- determination of the Hubble Constant

We propose to determine the luminosity of two type Ia supernovae {SNe
Ia}, 1995al in NGC 3021 and SN 2002fk in NGC 1309, by observing
Cepheids in their spiral hosts. Modern CCD photometry yields an
extremely tight Hubble diagram for SNe Ia with a precisely determined
intercept {i.e., Delta H_0/H_0}. Yet, the measurement of the true
Hubble constant via SNe Ia is limited by the calibration derived from
problematic and unreliable SN data. Most of the SNe Ia calibrated by
HST to date are significantly compromised by the systematics of
photographic photometry, high reddening and SN peculiarity, and by
the photometric anomolies associated with WFPC2. The extended reach
of ACS now provides opportunities to more reliably calibrate SNe Ia
and H_0. Our Cepheid calibration of a reliable SN Ia dataset, SN
1994ae, using ACS in Cycle 11 resulted in a 15% increase in H_0 from
the value derived by the HST SN Ia Calibration Program. Yet, there
remains a terribly small sample of reliable SN Ia data sets on which
to base such a crucial cosmological result. SN 1995al and SN 2002fk
are two of the best observed SNe Ia both with little reddening. They
provide two opportunities to use ACS for placing the calibration of
H_0 via SN Ia on firmer footing and potentially improve its

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/HRC 10473

Rings of Uranus: Dynamics, Particle Properties and Shepherding Moons

We propose to image the rings and small inner satellites of Uranus
using the High Resolution Channel of the ACS. The revolutionary
capabilities of the ACS will allow us to address a variety of
important questions relating to ring properties and ring-moon
interactions. Observations at a range of wavelengths and phase angles
will reveal the opposition surges of these rings and moons, providing
information on color and surface structure. Measurements of the ring
in front of the planet will provide complementary information on
optical depth; any variations of optical depth with wavelength will
reveal the rings’ poorly-constrained population of embedded dust. The
rings of Uranus are closing rapidly as the planet approaches equinox
in 2007, an event that takes place only every 42 years. Using this
opportunity, our observations will be repeated at different solar and
terrestrial tilt angles; this sequence of images will be particularly
valuable for constraining the physical thickness and packing density
of the rings. We will place particular emphasis on the rotational
variations of the Epsilon Ring, whose radial width {and therefore its
packing density} varies by a factor of five. In addition, deep
exposures through the CLEAR filter will enable us to detect and
recover 4-5 km moons in or near the ring system. Dynamicists invoke
numerous such moons to “shepherd” the many sharp ring boundaries, so
this will serve as a definitive test of the theory.

FGS 10432

Precise Distances to Nearby Planetary Nebulae

We propose to carry out astrometry with the FGS to obtain accurate
and precise distances to four nearby planetary nebulae. In 1992, Cahn
et al. noted that “The distances to Galactic planetary nebulae
remain a serious, if not THE most serious, problem in the field,
despite decades of study.” Twelve years later, the same statement
still applies. Because the distances to planetary nebulae are so
uncertain, our understanding of their masses, luminosities, scale
height, birth rate, and evolutionary state is severely limited. To
help remedy this problem, HST astrometry can guarantee parallaxes
with half the error of any other available approach. These data, when
combined with parallax measurements from the USNO, will improve
distance measurements by more than a factor of two, producing more
accurate distances with uncertainties that are of the order of ~6%.
Lastly, most planetary nebula distance scales in the literature are
statistical. They require several anchor points of known distance in
order to calibrate their zero point. Our program will provide “gold
standard” anchor points by the end of 2006, a decade before any
anticipated results from future space astrometry missions.

NIC3 10406

NICMOS Imaging of Massive Galaxies at z ~ 2

We propose NICMOS F160W imaging of a sample of massive red galaxies
from the Gemini Deep Deep Survey. These galaxies dominate the stellar
mass density at 1.5< z < 2 and are our best link to early galaxy formation. The NICMOS images will be used in conjunction with our ACS images and deep Gemini spectra to examine the formation and early evolution of massive ellpitcal galaxy progenitors. We waive all propretary rights to the data and wil make them available on our web site as we have done with the Gemini Deep Deep Survey spectra, catalogs and ACS images.

ACS/WFC/NIC3 10405

Probing the establishment of galaxy morphologies in the best-studied

We propose deep ACS I-band imaging of arguably the best-studied
high-redshift proto- cluster environment, a high-contrast structure
in the SSA22 field at z=3.1. Our on-going study of this region has
identified over 400 probable members of this structure across a
16-arcmin-square field, selected through narrow-band Lyman-alpha
emission, Lyman- break photometric criteria and far-infrared/radio
emission. Our proposed high-resolution imaging of galaxies in the
z=3.1 structure and in the nearby field, will provide morphological
information on galaxies over nearly two-orders of magnitude in local
density at this early epoch. This will allow us for the first time to
test whether galaxy morphology is defined at the formation of a
galaxy or reflects processes acting on it during its lifetime.


ACS CCDs daily monitor – Cycle 13 – Part 2

This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in ACS CCD detectors. The files, biases and dark will be used to
create reference files for science calibration. This program will be
for the entire lifetime of ACS.

ACS/HRC 10259

Planetary nebulae in the SMC: a study of stellar evolution and
populations in an extremely low-metallicity environment

The final phase of the evolution of low- and intermediate-mass stars,
the planetary nebula {PN} ejection, is thought to largely contribute
to the carbon and nitrogen enrichment in galaxies, in particular in
old stellar populations. Stellar generations forming from a carbon-
and nitrogen-enriched medium are a necessary condition for planetary
and life formation. It is essential to understand how stars go
through the process of shedding their chemically-enriched shells, and
to test the predictions of stellar evolution theory on the
relationship between stellar mass and elemental enrichment.
Magellanic Cloud PNs are ideal probes for this study. Their
abundances can be directly related to the mass of the central stars
and to that of the stellar progenitor, without the great {distance
and reddening} uncertainties that affect Galactic PNs. The UV lines
are essential for calculating the abundances of the element related
to stellar evolution {C, N, O} and to progenitor populations {e.g.,
Ne}. We propose to acquire UV spectroscopy of the SMC PNs whose
morphology and central star properties has been previously determined
by us with HST. We will derive the {C, N, O} abundance-to-mass
relation, and determine the extent to which the mass of the
progenitors of asymmetric PNs exceed that of symmetric PNs. We will
also test the PN luminosity function, and probe cosmic recycling, in
a very low-metallicity environment.

ACS/WFC 10210

Groups of Dwarf Galaxies: Pools of Mostly Dark Matter?

Within 5 Mpc, there are 6 groups with well-known luminous galaxies
but there also appears to be a comparable number of groups containing
only dwarfs. If these dwarf entities are truly bound then M/L values
are an order of magnitude higher than values found for groups with
luminous spiral galaxies. There are theoretical reasons to anticipate
that low mass halos may frequently be mostly dark. The dynamical
influence of low mass halos is negligible in familiar groups with
luminous members. By contrast, a study of the dynamics of `groups of
dwarfs’ may provide direct evidence of the existence of dark matter
potential wells with few baryons. The goal of the present study is to
gather detailed information on the 3-D distribution of dwarf galaxies
suspected to lie within 7 groups of dwarfs within 5 Mpc. Distances
with 7% relative accuracy can be measured with the Tip of the Giant
Branch method with ACS and integrations within 1 orbit per target.

ACS/WFC/NIC2 10189

PANS-Probing Acceleration Now with Supernovae

Type Ia supernovae {SNe Ia} provide the most direct evidence for an
accelerating Universe, a result widely attributed to dark energy.
Using HST in Cycle 11 we extended the Hubble diagram with 6 of the 7
highest-redshift SNe Ia known, all at z>1.25, providing conclusive
evidence of an earlier epoch of cosmic deceleration. The full sample
of 16 new SNe Ia match the cosmic concordance model and are
inconsistent with a simple model of evolution or dust as alternatives
to dark energy. Understanding dark energy may be the biggest current
challenge to cosmology and particle physics. To understand the nature
of dark energy, we seek to measure its two most fundamental
properties: its evolution {i.e., dw/dz}, and its recent equation of
state {i.e., w{z=0}}. SNe Ia at z>1, beyond the reach of the ground
but squarely within the reach of HST with ACS, are crucial to break
the degeneracy in the measurements of these two basic aspects of dark
energy. The SNe Ia we have discovered and measured with HST in Cycle
11, now double the precision of our knowledge of both properties.
Here we propose to quadruple the sample of SNe Ia at z>1 in the next
two cycles, complementing on-going surveys from the ground at z<1, and again doubling the precision of dark energy constraints. Should the current best fit model prove to be the correct one, the precision expected from the current proposal will suffice to rule out a cosmological constant at the 99% confidence level. Whatever the result, these objects will provide the basis with which to extend our empirical knowledge of this newly discovered and dominant component of the Universe, and will remain one of the most significant legacies of HST. In addition, our survey and follow-up data will greatly enhance the value of the archival data within the target Treasury fields for galaxy studies.

NIC2 10176

Coronagraphic Survey for Giant Planets Around Nearby Young Stars

A systematic imaging search for extra-solar Jovian planets is now
possible thanks to recent progress in identifying “young stars near
Earth”. For most of the proposed young {<~ 30 Myrs} and nearby {<~ 60 pc} targets, we can detect a few Jupiter-mass planets as close as a few tens of AUs from the primary stars. This represents the first time that potential analogs of our solar system - that is planetary systems with giant planets having semi-major axes comparable to those of the four giant planets of the Solar System - come within the grasp of existing instrumentation. Our proposed targets have not been observed for planets with the Hubble Space Telescope previously. Considering the very successful earlier NICMOS observations of low mass brown dwarfs and planetary disks among members of the TW Hydrae Association, a fair fraction of our targets should also turn out to posses low mass brown dwarfs, giant planets, or dusty planetary disks because our targets are similar to {or even better than} the TW Hydrae stars in terms of youth and proximity to Earth. Should HST time be awarded and planetary mass candidates be found, proper motion follow-up of candidate planets will be done with ground-based AOs.


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

HSTARS: (None)

9908 – GSAcq (2,3,3) results in finelock backup (3,0,3) scan step lmt
exc on FGS-2 @ 218/2314z GSAcq(2,3,3)scheduled at
218/23:14:50-23:22:09 resulted in finelock backup (3,0,3)using FGS-3
due to scan step limit exceeded on FGS-2 during walkdown.

9909 – GSAcq (2,1,2) results in finelock backup (1,0,1) scan step lmt
exc on FGS-2 @ 220/0043z GSAcq(2,1,2)scheduled at
220/00:43:39-00:50:51 resulted in finelock backup (1,0,1)using FGS-1
due to scan step limit exceeded on FGS-2 during walkdown. Prior FM
update showed the small errors



                              SCHEDULED     SUCCESSFUL 
 FGS Gsacq                  29                       29 
 FGS Reacq                  21                       21 
 FHST Update               43                        43 


SpaceRef staff editor.