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Daily Report #4577



 
 
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Old March 28th 08, 05:17 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #4577

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT****** # 4577

PERIOD COVERED: UT March 27, 2008 (DOY 087)

OBSERVATIONS SCHEDULED

FGS 11210

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 11301

Dynamical Masses and Radii of Four White Dwarf Stars

This proposal uses the FGS1r in TRANS mode to resolve a pair of double
degenerate binary systems {WD1639+153 and WD 1818+26} in order to
determine their orbital elements. In addition, the binaries and
several nearby field stars are observed by FGS1r in POS mode to
establish the local inertial reference frame of each binary, as well
as its parallax and proper motion. This will allow for a direct
measurement of the distance and radius of each of the four WD stars.
When combined with the orbital elements, this leads to a dynamical
mass measurement for each WD, and a four calibration points of the WD
mass-radius relation.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

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.

NIC3 11120

A Paschen-Alpha Study of Massive Stars and the ISM in the Galactic
Center

The Galactic center (GC) is a unique site for a detailed study of a
multitude of complex astrophysical phenomena, which may be common to
nuclear regions of many galaxies. Observable at resolutions
unapproachable in other galaxies, the GC provides an unparalleled
opportunity to improve our understanding of the interrelationships of
massive stars, young stellar clusters, warm and hot ionized gases,
molecular clouds, large scale magnetic fields, and black holes. We
propose the first large-scale hydrogen Paschen alpha line survey of
the GC using NICMOS on the Hubble Space Telescope. This survey will
lead to a high resolution and high sensitivity map of the Paschen
alpha line emission in addition to a map of foreground extinction,
made by comparing Paschen alpha to radio emission. This survey of the
inner 75 pc of the Galaxy will provide an unprecedented and complete
search for sites of massive star formation. In particular, we will be
able to (1) uncover the distribution of young massive stars in this
region, (2) locate the surfaces of adjacent molecular clouds, (3)
determine important physical parameters of the ionized gas, (4)
identify compact and ultra-compact HII regions throughout the GC. When
combined with existing Chandra and Spitzer surveys as well as a wealth
of other multi-wavelength observations, the results will allow us to
address such questions as where and how massive stars form, how
stellar clusters are disrupted, how massive stars shape and heat the
surrounding medium, and how various phases of this medium are
interspersed.

NIC3 11153

The Physical Nature and Age of Lyman Alpha Galaxies

In the simplest scenario, strong Lyman alpha emission from high
redshift galaxies would indicate that stellar populations younger than
10 Myrs dominate the UV. This does not, however, constrain the stellar
populations older than 100 Myrs, which do not contribute to UV light.
Also, the Lyman alpha line can be boosted if the interstellar medium
is both clumpy and dusty. Different studies with small samples have
reached different conclusions about the presence of dust and old
stellar populations in Lyman alpha emitters. We propose HST- NICMOS
and Spitzer-IRAC photometry of 35 Lyman-alpha galaxies at redshift
4.5z6.5, in order to determine their spectral energy distribution
{SED} extending through rest-frame optical. This will allow us to
measure accurately {1} The total stellar mass in these objects,
including old stars which may have formed at redshifts {z 8} not
easily probed by any other means. {2} The dust extinction in the
rest-frame UV, and therefore a correction to their present
star-formation rates. Taken together, these two quantities will yield
the star-formation histories of Lyman alpha galaxies, which form fully
half of the known galaxies at z=4-6. They will tell us whether these
are young or old galaxies by straddling the 4000A break. Data from
NICMOS is essential for these compact and faint {i=25-26th magnitude
AB} high redshift galaxies, which are too faint for good near-IR
photometry from the ground.

WFPC2 11083

The Structure, Formation and Evolution of Galactic Cores and Nuclei

A surprising result has emerged from the ACS Virgo Cluster Survey
{ACSVCS}, a program to obtain ACS/WFC gz imaging for a large, unbiased
sample of 100 early-type galaxies in the Virgo Cluster. On
subarcsecond scales {i.e., 0.1"-1"}, the HST brightness profiles vary
systematically from the brightest giants {which have nearly constant
surface brightness cores} to the faintest dwarfs {which have compact
stellar nuclei}. Remarkably, the fraction of galaxy mass contributed
by the nuclei in the faint galaxies is identical to that contributed
by supermassive black holes in the bright galaxies {0.2%}. These
findings strongly suggest that a single mechanism is responsible for
both types of Central Massive Object: most likely internally or
externally modulated gas inflows that feed central black holes or lead
to the formation of "nuclear star clusters". Understanding the history
of gas accretion, star formation and chemical enrichment on
subarcsecond scales has thus emerged as the single most pressing
question in the study of nearby galactic nuclei, either active or
quiescent. We propose an ambitious HST program {199 orbits} that
constitutes the next, obvious step forward: high-resolution,
ultraviolet {WFPC2/F255W} and infrared {NIC1/F160W} imaging for the
complete ACSVCS sample. By capitalizing on HST's unique ability to
provide high-resolution images with a sharp and stable PSF at UV and
IR wavelengths, we will leverage the existing optical HST data to
obtain the most complete picture currently possible for the history of
star formation and chemical enrichment on these small scales. Equally
important, this program will lead to a significant improvement in the
measured structural parameters and density distributions for the
stellar nuclei and the underlying galaxies, and provide a sensitive
measure of "frosting" by young stars in the galaxy cores. By virtue of
its superb image quality and stable PSF, NICMOS is the sole instrument
capable of the IR observations proposed here. In the case of the WFPC2
observations, high-resolution UV imaging { 0.1"} is a capability
unique to HST, yet one that could be lost at any time.

WFPC2 11198

Pure Parallel Imaging in the NDWFS Bootes Field

The NOAO Deep-Wide Field Survey {NDWFS} Bootes field is the target of
one of the most extensive multiwavelength campaigns in astronomy. In
addition to ground-based optical and near-infrared imaging, deep radio
mapping, and extensive spectroscopy, this entire region has been
imaged by the Chandra, Spitzer {IRAC and MIPS}, and GALEX missions.
Robust photometric redshifts {calibrated using over 20,000
spectroscopic redshifts} exist for all sources brighter than R=24.5 or
than 13 uJy at 4.5 microns. To enhance the value of this data set, we
propose pure parallel observations for all approved Cycle 16 programs
in this region that lack coordinated parallel observations. The
primary aim of this program will be to provide a database useful for
the broad range of science programs underway in this region.

WFPC2 11216

HST / Chandra Monitoring of a Dramatic Flare in the M87 Jet

As the nearest galaxy with an optical jet, M87 affords an unparalleled
opportunity to study extragalactic jet phenomena at the highest
resolution. During 2002, HST and Chandra monitoring of the M87 jet
detected a dramatic flare in knot HST-1 located ~1" from the nucleus.
Its optical brightness eventually increased seventy-fold and peaked in
2005; the X-rays show a similarly dramatic outburst. In both bands
HST-1 is still extremely bright and greatly outshines the galaxy
nucleus. To our knowledge this is the first incidence of an optical or
X-ray outburst from a jet region which is spatially distinct from the
core source -- this presents an unprecedented opportunity to study the
processes responsible for non-thermal variability and the X-ray
emission. We propose five epochs of HST/WFPC2 flux monitoring during
Cycle 16, as well as seven epochs of Chandra/ACIS observation {5ksec
each, six Chandra epochs contemporary with HST}. At two of the
HST/WFPC2 epochs we also gather spectral information, and at one epoch
we will map the magnetic field structure. The results of this
investigation are of key importance not only for understanding the
nature of the X-ray emission of the M87 jet, but also for
understanding flares in blazar jets, which are highly variable, but
where we have never before been able to resolve the flaring region in
the optical or X-rays. These new observations will allow us to track
the decay phase of the giant flare, and study smaller secondary flares
such as seen late in 2006. Ultimately we will test synchrotron
emission models for the X-ray outburst, constrain particle
acceleration and loss timescales, and study the jet dynamics
associated with this flaring component.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

*********************** SCHEDULED***** SUCCESSFUL

FGS GSacq************** 12**************** 12
FGS REacq************** 03**************** 03
OBAD with Maneuver **** 30*************** 30

SIGNIFICANT EVENTS: (None)


 




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