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 i
mages.
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
4.5<z<6.5,
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)