HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #
4576
PERIOD COVERED: UT March 26, 2008 (DOY 086)
OBSERVATIONS SCHEDULED
FGS 11211
An Astrometric Calibration of
Population II Distance Indicators
In 2002 HST produced a highly precise parallax for RR Lyrae. That
measurement
resulted in an absolute magnitude, M{V}= 0.61+/-0.11, a
useful result,
judged by the over ten refereed citations each year
since. It is,
however, unsatisfactory to have the direct,
parallax-based,
distance scale of Population II variables based on a
single star.
We propose, therefore, to obtain the parallaxes of four
additional RR Lyrae stars and two Population II Cepheids,
or
stars. The
Population II Cepheids lie with the RR Lyrae stars on a
common K-band
Period-Luminosity relation. Using these parallaxes to
inform that
relationship, we anticipate a zero-point error of 0.04
magnitude. This
result should greatly strengthen confidence in the
Population II distance scale and increase our
understanding of RR Lyrae
star and Pop
II Cepheid astrophysics.
FGS 11213
Distances to Eclipsing M Dwarf Binaries
We propose HST FGS observations to measure accurate
distances of 5
nearby M dwarf
eclipsing binary systems, from which model-independent
luminosities can be
calculated. These objects have either poor or no
existing
parallax measurements. FGS parallax determinations for these
systems, with
their existing dynamic masses determined to better than
0.5%, would serve as model-independent anchor points for
the low-mass
end of the
mass-luminosity diagram.
NIC1/NIC2/NIC3 11330
NICMOS Cycle 16 Extended Dark
This takes a series of Darks in parallel to other
instruments.
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.
NIC2 11219
Active Galactic Nuclei in nearby galaxies: a new view of
the origin of
the
radio-loud radio-quiet dichotomy?
Using archival HST and Chandra observations of 34 nearby
early-type
galaxies {drawn
from a complete radio selected sample} we have found
evidence that
the radio-loud/radio-quiet dichotomy is directly connected
to the
structure of the inner regions of their host galaxies in the
following sense:
[1] Radio-loud AGN are associated with galaxies with
shallow cores
in their light profiles [2] Radio-quiet AGN are only
hosted by
galaxies with steep cusps. Since the brightness profile is
determined by the
galaxy's evolution, through its merger history, our
results suggest
that the same process sets the AGN flavour. This
provides us with
a novel tool to explore the co-evolution of galaxies
and supermassive black holes, and it opens a new path to
understand the
origin of the
radio-loud/radio-quiet AGN dichotomy. Currently our
analysis is
statistically incomplete as the brightness profile is not
available for 82
of the 116 targets. Most galaxies were not observed
with HST,
while in some cases the study is obstructed by the presence of
dust
features. We here propose to perform an infrared NICMOS snapshot
survey of
these 82 galaxies. This will enable us to i} test the
reality
of the dichotomic behaviour in a
substantially larger sample; ii} extend
the
comparison between radio-loud and radio-quiet AGN to a larger range
of
luminosities.
NIC3 10899
Identifying z>7 galaxies from J-dropouts
NICMOS Parallel Imaging campaigns covered enough sky {250 pointings}
with enough
sensitivity in the 110W and 160W filters to identify 6
extremely red
resolved sources which are prime candidates for J-band
dropouts. Their
complete absence of detectable J band flux can be caused
by an
opaque Lyman cut-off at z=8-10. We propose to follow up these
candidates with
NICMOS imaging and jointly propose Spitzer IRAC
photometry. Deep
F110W and Spitzer/IRAC 3.5/4.8 micron imaging will
confirm if any
of these candidates are indeed Lyman Break galaxies
observed less
than 500 Myrs after the Big Bang. Genuine LBGs will remain
undetected in
F110W, while being detected with flat spectra in the IRAC
bands. The
combined SED will provide information about the stellar mass
of these
galaxies, and the possible presence of evolved stars or dust
reddening. The
proposed observations will be sensitive enough to detect
the F110W
flux from galaxies as red as {J-H}=2.8 {AB mags, 5
sigma}. If
any of the
candidates are detected with bluer colors, they will most
likely be
exceptional "Distant Red Galaxies" at z of 4 to 6. The
proposed data
will constrain the stellar populations of these
extraordinarily red
galaxies, which would be candidates for the
earliest, most
massive galaxies which formed.
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.
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 11113
Binaries in the Kuiper Belt:
Probes of Solar System Formation and
Evolution
The discovery of binaries in the Kuiper
Belt and related small body
populations is
powering a revolutionary step forward in the study of
this remote
region. Three quarters of the known binaries in the Kuiper
Belt have been
discovered with HST, most by our snapshot surveys. The
statistics derived
from this work are beginning to yield surprising and
unexpected
results. We have found a strong concentration of binaries
among
low-inclination Classicals, a possible size cutoff to
binaries
among the
Centaurs, an apparent preference for nearly equal mass
binaries, and a
strong increase in the number of binaries at small
separations. We
propose to continue this successful program in Cycle 16;
we expect
to discover at least 13 new binary systems, targeted to
subgroups where
these discoveries can have the greatest impact.
WFPC2 11202
The Structure of Early-type Galaxies: 0.1-100 Effective
Radii
The structure, formation and evolution of early-type
galaxies is still
largely an open
problem in cosmology: how does the Universe evolve from
large linear
scales dominated by dark matter to the highly non-linear
scales of
galaxies, where baryons and dark matter both play important,
interacting, roles?
To understand the complex physical processes
involved in
their formation scenario, and why they have the tight
scaling
relations that we observe today {e.g. the Fundamental Plane}, it
is
critically important not only to understand their stellar structure,
but also
their dark-matter distribution from the smallest to the largest
scales. Over
the last three years the SLACS collaboration has developed
a toolbox
to tackle these issues in a unique and encompassing way by
combining new
non-parametric strong lensing techniques, stellar
dynamics, and
most recently weak gravitational lensing, with
high-quality Hubble
Space Telescope imaging and VLT/Keck spectroscopic
data of
early-type lens systems. This allows us to break degeneracies
that are
inherent to each of these techniques separately and probe the
mass
structure of early-type galaxies from 0.1 to 100 effective radii.
The large dynamic range to which lensing
is sensitive allows us both to
probe the
clumpy substructure of these galaxies, as well as their
low-density outer
haloes. These methods have convincingly been
demonstrated, by our
team, using smaller pilot-samples of SLACS lens
systems with
HST data. In this proposal, we request observing time with
WFPC2 and NICMOS to observe 53 strong lens systems from
SLACS, to obtain
complete
multi-color imaging for each system. This would bring the total
number of
SLACS lens systems to 87 with completed HST imaging and
effectively doubles
the known number of galaxy-scale strong lenses. The
deep HST
images enable us to fully exploit our new techniques, beat down
low-number
statistics, and probe the structure and evolution of
early-type
galaxies, not only with a uniform data-set an order of
magnitude larger
than what is available now, but also with a fully
coherent and
self-consistent methodological approach!
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 11 11
FGS REacq 02 02
OBAD with Maneuver 26 26
SIGNIFICANT EVENTS: (None)
-
____________________________________________________________
Lynn F. Bassford
Hubble Space Telescope
CHAMP
CHAMP Flight Operations Team Manager
Lockheed Martin
NASA GSFC PH#: 301-286-2876
"The Hubble Space Telescope is
the astronomical observatory and key to unlocking the most cosmic mysteries of
the past, present and future." - 7/26/6