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Daily Report #5105



 
 
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Old May 27th 10, 04:20 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #5105

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 z3 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 z5.3 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 (4d21 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/N10) 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.

 




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