HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT # 4591
PERIOD
COVERED: UT April 16, 2008 (DOY 107)
OBSERVATIONS
SCHEDULED
ACS/SBC/WFPC2
11230
HST
FUV Observations of Brightest Cluster Galaxies: The Role of Star
Formation
in Cooling Flows and BCG Evolution
The
intracluster medium (ICM) now appears to be a very dynamic place
where
heating and cooling processes vie for dominance and an uneasy
equilibrium
is maintained. Since these same processes may operate during
the
process of galaxy formation, the centers of clusters of galaxies
provide
low redshift laboratories for studying the critical processes
involved
in galaxy formation and black hole growth. At the present time,
the
main questions are (1) How much gas is cooling out of the ICM? (2)
How
much star formation is ongoing? (3) What is the impact of the gas
and
star formation on the central BCG? In order to measure the current
star
formation in BCGs we have undertaken a program of Spitzer IRAC and
MIPS
observations. We are in process of obtaining observations of a
sample
of Brightest Cluster Galaxies in 70 clusters selected from the
ROSAT
all sky survey. In about 25% of the sources observed so far, we
detect
a mid-IR excess which we attribute to dust heated by star
formation.
We propose to obtain ACS/SBC observations of the Lyman Alpha
emission
line and the adjacent FUV continuum in 7 BCGs which are in
cooling
core clusters of galaxies and have a large mid-IR excess. We
also
propose WFPC2 F606W observations of the two clusters without high
resolution
imaging to allow us to image the dust on the same scale as
the
Far UV continuum. The FUV will allow us to confirm the presense of
ongoing
starformation in these BCGs and will allow us to rule out an AGN
as
the dominant contributer to the mid-IR. The morphology and spatial
extent
of the young stars and the heated dust and CO will constrain the
spatial
scale over which star formation occurs and thus where the
cooling
gas is deposited. The combination of our FUV and IR observations
will
allow us to estimate the star formation rates which must balance
the
rate at which cold gas is deposited in the BCG. Our proposed FUV
observations
will produce unique information about the cooling gas, the
true
mass accretion rates, and the star formation rates in BCGs and its
effect
on the galaxy.
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.
WFPC2
11125
The
Dynamical Evolution of Globular Clusters
Globular
clusters evolve through dynamical interactions, with primordial
binaries
extending the time until core collapse by up to an order of
magnitude,
depending on the initial binary fraction. These dynamical
interactions
plus mass segregation causes the binary fraction to rise in
the
core but fall at larger radii. We hope to eventually test these
broad
predictions by comparing them to the binary properties for
globular
clusters at different states of evolution, defined by the ratio
of
their age to the dynamical relaxation time at the half-light radius.
The
most important unknown aspects in the modeling process are the
initial
conditions of binaries in the cluster. Here we propose to
determine
the initial binary fraction as a function of radius by
studying
three of the dynamically youngest globular clusters {NGC 5053,
NGC
5466, and NGC 5897}. The presence of binaries thickens the Main
Sequence
in a color-magnitude diagram, which can be detected with deep
multicolor
images.
WFPC2
11130
AGNs
with Intermediate-mass Black Holes: Testing the Black Hole-Bulge
Paradigm,
Part II
The
recent progress in the study of central black holes in galactic
nuclei
has led to a general consensus that supermassive {10^6-10^9 solar
mass}
black holes are closely connected with the formation and
evolutionary
history of large galaxies, especially their bulge
component.
Two outstanding issues, however, remain unresolved. Can
central
black holes form in the absence of a bulge? And does the mass
function
of central black holes extend below 10^6 solar masses?
Intermediate-mass
black holes {<10^6 solar masses}, if they exist, may
offer
important clues to the nature of the seeds of supermassive black
holes.
Using the SDSS, our group has successfully uncovered a new
population
of AGNs with intermediate-mass black holes that reside in
low-luminosity
galaxies. However, very little is known about the
detailed
morphologies or structural parameters of the host galaxies
themselves,
including the crucial question of whether they have bulges
or
not. Surprisingly, the majority of the targets of our Cycle 14 pilot
program
have structural properties similar to dwarf elliptical galaxies.
The
statistics from this initial study, however, are really too sparse
to
reach definitive conclusions on this important new class of black
holes.
We wish to extend this study to a larger sample, by using the
Snapshot
mode to obtain WFPC2 F814W images from a parent sample of 175
AGNs
with intermediate- mass black holes selected from our final SDSS
search.
We are particularly keen to determine whether the hosts contain
bulges,
and if so, how the fundamental plane properties of the host
depend
on the mass of their central black holes. We will also
investigate
the environment of this unique class of AGNs.
WFPC2
11132
Constraining
the age of the AB Dor system
The
zero-age main sequence K-type star AB Dor, with an age of 25 to 125
Myr,
is the most active young star in the solar neighbourhood. It is
part
of a quadruple system of young stars. The mass of AB Dor C, the
closest
and lowest mass companion, has been derived from astrometric
observations
(with the VLA and adaptive optics at the VLT) to 94+-3
times
the mass of Jupiter. The low mass (close to the hydrogen burning
limit)
combined with the young age makes AB Dor C a unique calibration
source
for evolutionary tracks for very low-mass stars and brown dwarfs,
provided
that a precise age estimate can be derived for the system. We
propose
to use the HST planetary camera to obtain resolved component
photometry
of the M-type pre-main sequence star AB Dor Ba and Bb in
order
to derive individual spectral types and luminosities, which will
enable
us to age-date the AB Dor system to better than +-20 Myr. In
addition,
the observations will help to constrain the Ba/Bb orbit, and
hence
to derive dynamical mass estimates as well.
WFPC2
11235
HST
NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies
in
the Local Universe
At
luminosities above 10^11.4 L_sun, the space density of far-infrared
selected
galaxies exceeds that of optically selected galaxies. These
`luminous
infrared galaxies' {LIRGs} are primarily interacting or
merging
disk galaxies undergoing enhanced star formation and Active
Galactic
Nuclei {AGN} activity, possibly triggered as the objects
transform
into massive S0 and elliptical merger remnants. We propose
NICMOS
NIC2 imaging of the nuclear regions of a complete sample of 88
L_IR
> 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised
Bright
Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}.
This
sample is ideal not only in its completeness and sample size, but
also
in the proximity and brightness of the galaxies. The superb
sensitivity
and resolution of NICMOS NIC2 on HST enables a unique
opportunity
to study the detailed structure of the nuclear regions,
where
dust obscuration may mask star clusters, AGN and additional nuclei
from
optical view, with a resolution significantly higher than possible
with
Spitzer IRAC. This survey thus provides a crucial component to our
study
of the dynamics and evolution of IR galaxies presently underway
with
Wide-Field, HST ACS/WFC and Spitzer IRAC observations of these 88
galaxies.
Imaging will be done with the F160W filter {H-band} to examine
as
a function of both luminosity and merger stage {i} the luminosity and
distribution
of embedded star clusters, {ii} the presence of optically
obscured
AGN and nuclei, {iii} the correlation between the distribution
of 1.6
micron emission and the mid- IR emission as detected by Spitzer
IRAC,
{iv} the evidence of bars or bridges that may funnel fuel into the
nuclear
region, and {v} the ages of star clusters for which photometry
is
available via ACS/WFC observations. The NICMOS data, combined with
the
HST ACS, Spitzer, and GALEX observations of this sample, will result
in
the most comprehensive study of merging and interacting galaxies to
date.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
11255
- GSAcq(2,1,2) failed to RGA Hold (Gyro Control)
Upon acquisition of siganl at 107/16:22:31, the GSAcq(2,1,2)
scheduled
at 107/15:08:24 - 15:16:29 failed to RGA Hold due to (QF1STOPF)
stop
flag indication on FGS-1. Pre-acquisition OBADs (RSS) attitude
correction values are not available due to LOS. Post-acq OBAD/MAP
had
(RSS) value of 1373.29 arcseconds.
COMPLETED
OPS REQUEST:
18225-0
- Modify RWA Spin Down Estimate Parameters @107/1314z
18054-0
- Preview KF Sun Vector Data via Telemetry Diags @107/1321z
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSacq
08
07
FGS
REacq
04
04
OBAD
with Maneuver
24
24
SIGNIFICANT
EVENTS: (None)