HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5105
PERIOD
COVERED: 5am May 26 - 5am May 27, 2010 (DOY 146/09:00z-147/09:00z)
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
07
07
FGS
REAcq
08
08
OBAD
with Maneuver 04 04
SIGNIFICANT
EVENTS: (None)
OBSERVATIONS
SCHEDULED:
COS/FUV
11592
Testing
the Origin(s) of the Highly Ionized High-Velocity Clouds: A
Survey
of Galactic Halo Stars at z>3 kpc
Cosmological
simulation predicts that highly ionized gas plays an
important
role in the formation and evolution of galaxies and their
interplay
with the intergalactic medium. The NASA HST and FUSE missions
have
revealed high-velocity CIV and OVI absorption along extragalactic
sightlines
through the Galactic halo. These highly ionized high-velocity
clouds
(HVCs) could cover 85% of the sky and have a detection rate
higher
than the HI HVCs. Two competing, equally exciting, theories may
explain
the origin of these highly ionized HVCs: 1) the "Galactic"
theory,
where the HVCs are the result of feedback processes and trace
the
disk-halo mass exchange, perhaps including the accretion of matter
condensing
from an extended corona; 2) the "Local Group" theory, where
they
are part of the local warm-hot intergalactic medium, representing
some
of the missing baryonic matter of the Universe. Only direct
distance
determinations can discriminate between these models. Our group
has
found that some of these highly ionized HVCs have a Galactic origin,
based
on STIS observations of one star at z<5.3 kpc. We propose an HST
FUV
spectral survey to search for and characterize the high velocity NV,
CIV,
and SiIV interstellar absorption toward 24 stars at much larger
distances
than any previous searches (4<d<21 kpc, 3<|z|<13 kpc). COS
will
provide atomic to highly ionized species (e.g., OI, CII, CIV, SiIV)
that
can be observed at sufficient resolution (R~22, 000) to not only
detect
these highly ionized HVCs but also to model their properties and
understand
their physics and origins. This survey is only possible
because
of the high sensitivity of COS in the FUV spectral range.
COS/FUV
11692
The
LMC as a QSO Absorption Line System
We
propose to obtain high resolution, high signal-to-noise observations
of
QSOs behind the Large Magellanic Clouds. These QSOs are situated
beyond
the star forming disk of the galaxy, giving us the opportunity to
study
the distribution of metals and energy in regions lacking
significant
star formation. In particular, we will derive the
metallicities
and study the ionization characteristics of LMC gas at
impact
parameters 3-17 kpc. We will compare our results with high-z QSO
absorption
line systems.
COS/FUV
11895
FUV
Detector Dark Monitor
Monitor
the FUV detector dark rate by taking long science exposures
without
illuminating the detector. The detector dark rate and spatial
distribution
of counts will be compared to pre-launch and SMOV data in
order
to verify the nominal operation of the detector. Variations of
count
rate as a function of orbital position will be analyzed to find
dependence
of dark rate on proximity to the SAA. Dependence of dark rate
as
function of time will also be tracked.
COS/FUV/COS/NUV
11598
How
Galaxies Acquire their Gas: A Map of Multiphase Accretion and
Feedback
in Gaseous Galaxy Halos
We
propose to address two of the biggest open questions in galaxy
formation
- how galaxies acquire their gas and how they return it to the
IGM
- with a concentrated COS survey of diffuse multiphase gas in the
halos
of SDSS galaxies at z = 0.15 - 0.35. Our chief science goal is to
establish
a basic set of observational facts about the physical state,
metallicity,
and kinematics of halo gas, including the sky covering
fraction
of hot and cold material, the metallicity of infall and
outflow,
and correlations with galaxy stellar mass, type, and color -
all
as a function of impact parameter from 10 - 150 kpc. Theory suggests
that
the bimodality of galaxy colors, the shape of the luminosity
function,
and the mass-metallicity relation are all influenced at a
fundamental
level by accretion and feedback, yet these gas processes are
poorly
understood and cannot be predicted robustly from first
principles.
We lack even a basic observational assessment of the
multiphase
gaseous content of galaxy halos on 100 kpc scales, and we do
not
know how these processes vary with galaxy properties. This ignorance
is
presently one of the key impediments to understanding galaxy
formation
in general. We propose to use the high-resolution gratings
G130M
and G160M on the Cosmic Origins Spectrograph to obtain sensitive
column
density measurements of a comprehensive suite of multiphase ions
in
the spectra of 43 z < 1 QSOs lying behind 43 galaxies selected from
the
Sloan Digital Sky Survey. In aggregate, these sightlines will
constitute
a statistically sound map of the physical state and
metallicity
of gaseous halos, and subsets of the data with cuts on
galaxy
mass, color, and SFR will seek out predicted variations of gas
properties
with galaxy properties. Our interpretation of these data will
be
aided by state-of-the-art hydrodynamic simulations of accretion and
feedback,
in turn providing information to refine and test such models.
We
will also use Keck, MMT, and Magellan (as needed) to obtain optical
spectra
of the QSOs to measure cold gas with Mg II, and optical spectra
of
the galaxies to measure SFRs and to look for outflows. In addition to
our
other science goals, these observations will help place the Milky
Way's
population of multiphase, accreting High Velocity Clouds (HVCs)
into
a global context by identifying analogous structures around other
galaxies.
Our program is designed to make optimal use of the unique
capabilities
of COS to address our science goals and also generate a
rich
dataset of other absorption-line systems along a significant total
pathlength
through the IGM (Delta z ~ 20).
COS/FUV/COS/NUV
11829
Coronal
and Transition Region Heating Due to Magnetic Activity on
Metal-Poor
Dwarf Stars
How
does low metallicity affect the heating and resultant temperature
structure
of the chromospheres, transition regions, and coronae of old
solar-like
dwarf stars? Our ACIS-S observations of 7 Gyr old Arcturus
Moving
Group (AMG) dwarfs show very little conventional coronal (> 1 MK)
plasma
and suggest that these stars have insufficient magnetic energy
input
to power a solar-like corona. However, they do have chomospheres
and
transition regions similar to the minimum activity Quiet Sun. It
this
typical or an aberration of the AMG? We propose a 35 ksec ACIS-S
observation
and HST COS spectroscopy of the nearest (9.2 pc), truely
metal-poor
([Fe/H] = -1.4) dwarf star that is known to have definite
magnetic
dynamo activity (activity cycles, active region modulation) --
HD103095
-- to investigate this question further.
COS/NUV
11667
Detailed
Probing of a 3000 km/s Ly-alpha + Metal Line Absorption Complex
Near
Two Galaxies at z=0.67
At
intermediate redshifts, Ly-alpha absorbers cluster around rich
metal-line
systems [those with numerous low and high ionization species
(Bahcall
et al.)], and at z=3, higher ionization clouds reside at the
velocity
extremes of clustered Ly-alpha lines, a signature of the
physics
of collapse and layered gas structures (Songaila & Cowie). These
extraordinary
HI environments provide unique astrophysical laboratories
for
probing relatively high overdensity IGM structures and for placing
powerful
constraints on our understanding of the intergalactic medium
and
extended galaxy halos in the context of structure evolution,
galactic
stellar feedback chemical enrichment to large galactocentric
distances,
and the cosmic baryon budget.
We
have undertaken a comprehensive study of the remarkable 1400 km/s
velocity
width, optically thin Ly-alpha only complex (five components)
at
z=0.67 within 1600 km/s of the Lyman limit z=0.66 metal-line system
toward
TON 153 (Churchill et al.). We have collected FOS, STIS, and
HIRES
quasar spectra covering the Lyman series, OVI, CIV, and MgII
absorption,
an F702W/WFPC-2 image, and set of ground based narrow-band
SDSS
filter images of the quasar field. Two galaxies aligned in velocity
with
the z=0.67 Ly-alpha complex and z=0.66 metal-line system lie within
100
kpc of the quasar sightline; the absorption is not consistent with
our
standard model of extended "halo" gas for either galaxy, which
suggests
that a large scale structure (i.e., filament) may extend
between
these galaxies.
We
propose to obtain G160M/1600 and G185M/1921+1941 (S/N>10) COS spectra
of
the z=1.01 quasar TON 153 to obtain detailed kinematic, chemical, and
ionization
conditions of this extraordinary absorber/galaxy system
(total
velocity spread 3000 km/s). The propose observations will provide
an
unprecedented first high resolution examination of the full Lyman
series
and MgII, CIV, and OVI metal lines arising in galaxy halos or a
possible
large scale structure (i.e., filament) asscociated with
thoroughly
studied galaxies. We aim to discern if the HI extends between
the
galaxies and test for multiphase absorption signatures suggestive of
a
galactic feedback or large scale collapsing structure.
FGS
11704
The
Ages of Globular Clusters and the Population II Distance Scale
Globular
clusters are the oldest objects in the universe whose age can
be
accurately determined. The dominant error in globular cluster age
determinations
is the uncertain Population II distance scale. We propose
to
use FGS 1r to obtain parallaxes with an accuracy of 0.2
milliarcsecond
for 9 main sequence stars with [Fe/H] < -1.5. This will
determine
the absolute magnitude of these stars with accuracies of 0.04
to
0.06mag. This data will be used to determine the distance to 24
metal-poor
globular clusters using main sequence fitting. These
distances
(with errors of 0.05 mag) will be used to determine the ages
of
globular clusters using the luminosity of the subgiant branch as an
age
indicator. This will yield absolute ages with an accuracy 5%, about
a
factor of two improvement over current estimates. Coupled with
existing
parallaxes for more metal-rich stars, we will be able to
accurately
determine the age for globular clusters over a wide range of
metallicities
in order to study the early formation history of the Milky
Way
and provide an independent estimate of the age of the universe.
The
Hipparcos database contains only 1 star with [Fe/H] < -1.4 and an
absolute
magnitude error less than 0.18 mag which is suitable for use in
main
sequence fitting. Previous attempts at main sequence fitting to
metal-poor
globular clusters have had to rely on theoretical
calibrations
of the color of the main sequence. Our HST parallax program
will
remove this source of possible systematic error and yield distances
to
metal-poor globular clusters which are significantly more accurate
than
possible with the current parallax data. The HST parallax data will
have
errors which are 10 times smaller than the current parallax data.
Using
the HST parallaxes, we will obtain main sequence fitting distances
to
11 globular clusters which contain over 500 RR Lyrae stars. This will
allow
us to calibrate the absolute magnitude of RR Lyrae stars, a
commonly
used Population II distance indicator.
S/C
12046
COS
FUV DCE Memory Dump
Whenever
the FUV detector high voltage is on, count rate and current
draw
information is collected, monitored, and saved to DCE memory. Every
10
msec the detector samples the currents from the HV power supplies
(HVIA,
HVIB) and the AUX power supply (AUXI). The last 1000 samples are
saved
in memory, along with a histogram of the number of occurrences of
each
current value.
In
the case of a HV transient (known as a "crackle" on FUSE), where one
of
these currents exceeds a preset threshold for a persistence time, the
HV
will shut down, and the DCE memory will be dumped and examined as
part
of the recovery procedure. However, if the current exceeds the
threshold
for less than the persistence time (a "mini-crackle" in FUSE
parlance),
there is no way to know without dumping DCE memory. By
dumping
and examining the histograms regularly, we will be able to
monitor
any changes in the rate of "mini-crackles" and thus learn
something
about the state of the detector.
STIS/CCD
11567
Boron
Abundances in Rapidly Rotating Early-B Stars.
Models
of rotation in early-B stars predict that rotationally driven
mixing
should deplete surface boron abundances during the main-sequence
lifetime
of many stars. However, recent work has shown that many boron
depleted
stars are intrinsically slow rotators for which models predict
no
depletion should have occurred, while observations of nitrogen in
some
more rapidly rotating stars show less mixing than the models
predict.
Boron can provide unique information on the earliest stages of
mixing
in B stars, but previous surveys have been biased towards
narrow-lined
stars because of the difficulty in measuring boron
abundances
in rapidly rotating stars. The two targets observed as part
of
our Cycle 13 SNAP program 10175, just before STIS failed, demonstrate
that
it is possible to make useful boron abundance measurements for
early-B
stars with Vsin(i) above 100 km/s. We propose to extend that
survey
to a large enough sample of stars to allow statistically
significant
tests of models of rotational mixing in early-B stars.
STIS/CCD
11845
CCD
Dark Monitor Part 2
Monitor
the darks for the STIS CCD.
STIS/CCD
11847
CCD
Bias Monitor-Part 2
Monitor
the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1,
and
1x1 at gain = 4, to build up high-S/N superbiases and track the
evolution
of hot columns.
WFC3/UVI
11909
UVIS
Hot Pixel Anneal
The
on-orbit radiation environment of WFC3 will continually generate new
hot
pixels. This proposal performs the procedure required for repairing
those
hot pixels in the UVIS CCDs. During an anneal, the two-stage
thermo-electric
cooler (TEC) is turned off and the four-stage TEC is
used
as a heater to bring the UVIS CCDs up to ~20C. As a result of the
CCD
warmup, a majority of the hot pixels will be fixed; previous
instruments
such as WFPC2 and ACS have seen repair rates of about 80%.
Internal
UVIS exposures are taken before and after each anneal, to allow
an
assessment of the procedure's effectiveness in WFC3, provide a check
of
bias, global dark current, and hot pixel levels, as well as support
hysteresis
(bowtie) monitoring and CDBS reference file generation. One
IR
dark is taken after each anneal, to provide a check of the IR
detector.