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Daily Rpt #4426



 
 
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Old August 15th 07, 08:26 PM posted to sci.astro.hubble
Bassford, Lynn
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Posts: 44
Default Daily Rpt #4426

Notice: Due to the conversion of some ACS WFC or HRC observations into
WFPC2, or NICMOS observations after the loss of ACS CCD science
capability in January, there may be an occasional discrepancy between
a proposal's listed (and correct) instrument usage and the abstract
that follows it.

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT*** # 4426

PERIOD COVERED: UT August 14, 2007 (DOY 226)

OBSERVATIONS SCHEDULED

ACS/SBC 10840

The FUV fluxes of Tauri stars in the Taurus molecular cloud

Present and forthcoming ground-based and space surveys of the T Tauri
stars in the Taurus molecular cloud will provide information from high
energy stellar and accretion radiation to low energy solid state and
molecular emission from the disk, making those stars perfect
laboratories to carry out self-consistent studies of disk physics and
evolution. We propose to complete this wealth of information by
obtaining ACS/FUV spectra for a significant sample of Taurus T Tauri
stars, covering a range of accretion properties and dust evolutionary
stages. FUV fluxes carry ~ 10 - 100 more energy than X-rays into these
disks and are thus crucial gas heating agents and key to disk
dispersal by photoevaporation. These observations are a pre-requisite
to interpret observations with Spitzer, SOFIA, Herschel, and ALMA, and
will become one of the important legacies of HST to the star formation
community.

ACS/SBC 10864

Mapping the Gaseous Content of Protoplanetary and Young Planetary
Systems with ACS

One of the key problems in planetary system formation is understanding
how rapidly, and over what time interval Jovian planets can form. Dust
in the protoplanetary disk is critical in planetesimal formation, but
it is the gas which produces giant planets, and which is essential for
their migration. However, compared to data on the circumstellar dust,
information on the gas component is sparse, especially in the
planet-formation zone. This severely limits our ability to put
observational constraints on giant planet formation, except to note
that the process must be largely complete by 12 Myr, given the paucity
of Herbig Ae or classical T Tauri stars older than 10-12 Myr. In the
FUV, photo-excited molecular hydrogen transitions have the requisite
contrast to the stellar photosphere, accretion shock, and reflection
nebulosity, and can be traced 50-100 AU from the exciting stars in
both envelopes and outflow cavities and protoplanetary disks. Central
disk cavities, an expected consequence of planet formation, larger
than 0.1" are directly detectable in HST FUV spectra, while smaller
cavities may be detected by comparison with protoplanetary disks which
are still accreting onto their stars. We propose augmenting existing
HST coronagraphic imagery of 6 Herbig Fe and T Tauri disks with ACS
Solar-Blind Channel Lyman alpha imagery and slitless spectroscopy
simultaneously sampling the disk in molecular hydrogen and small-grain
reflection nebulosity. These data will be used to quantify the amount
of vertical stratification in these disks, to map the mass-loss
geometry from the star, and to determine whether removal of molecular
material preceds, lags, or is contemporary with clearing of the dust.

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration - CR Persistence Part 5

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 DARKs. 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 images. 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.

WFPC2 11128

Time Scales Of Bulge Formation In Nearby Galaxies

Traditionally, bulges are thought to fit well into galaxy formation
models of hierarchical merging. However, it is now becoming well
established that many bulges formed through internal, secular
evolution of the disk rather than through mergers. We call these
objects pseudobulges. Much is still unknown about pseudobulges, the
most pressing questions being: How, exactly, do they build up their
mass? How long does it take? And, how many exist? We are after an
answer to these questions. If pseudobulges form and evolve over longer
periods than the time between mergers, then a significant population
of pseudobulges is hard to explain within current galaxy formation
theories. A pseudobulge indicates that a galaxy has most likely not
undergone a major merger since the formation of the disk. The ages of
pseudobulges give us an estimate for the time scale of this quiescent
evolution. We propose to use 24 orbits of HST time to complete UBVIH
imaging on a sample of 33 nearby galaxies that we have observed with
Spitzer in the mid-IR. These data will be used to measure spatially
resolved stellar population parameters {mean stellar age, metallicity,
and star formation history}; comparing ages to star formation rates
allows us to accurately constrain the time scale of pseudobulge
formation. Our sample of bulges includes both pseudo- and classical
bulges, and evenly samples barred and unbarred galaxies. Most of our
sample is imaged, 13 have complete UBVIH coverage; we merely ask to
complete missing observations so that we may construct a uniform
sample for studying bulge formation. We also wish to compare the
stellar population parameters to a variety of bulge and global galaxy
properties including star formation rates, dynamics, internal bulge
morphology, structure from bulge-disk decompositions, and gas content.
Much of this data set is already or is being assembled. This will
allow us to derive methods of pseudobulge identification that can be
used to accurately count pseudobulges in large surveys. Aside from our
own science goals, we will present this broad set of data to the
community. Thus, we waive proprietary periods for all observations.

WFPC2 11229

SEEDS: The Search for Evolution of Emission from Dust in Supernovae
with HST and Spitzer

The role that massive stars play in the dust content of the Universe
is extremely uncertain. It has long been hypothesized that dust can
condense within the ejecta of supernovae {SNe}, however there is a
frustrating discrepancy between the amounts of dust found in the early
Universe, or predicted by nucleation theory, and inferred from SN
observations. Our SEEDS collaboration has been carefully revisiting
the observational case for dust formation by core-collapse SNe, in
order to quantify their role as dust contributors in the early
Universe. As dust condenses in expanding SN ejecta, it will increase
in optical depth, producing three simultaneously observable phenomena:
{1} increasing optical extinction; {2} infrared {IR} excesses; and {3}
asymmetric blue-shifted emission lines. Our SEEDS collaboration
recently reported all three phenomena occurring in SN2003gd,
demonstrating the success of our observing strategy, and permitting us
to derive a dust mass of up to 0.02 solar masses created in the SN. To
advance our understanding of the origin and evolution of the
interstellar dust in galaxies, we propose to use HST's WFPC2 and
NICMOS instruments plus Spitzer's photometric instruments to monitor
ten recent core- collapse SNe for dust formation and, as a bonus,
detect light echoes that can affect the dust mass estimates. These
space-borne observations will be supplemented by ground- based
spectroscopic monitoring of their optical emission line profiles.
These observations would continue our 2-year HST and Spitzer
monitoring of this phenomena in order to address two key questions: Do
all SNe produce dust? and How much dust do they produce? As all the SN
are witin 15 Mpc, each SN stands an excellent chance of detection with
HST and Spitzer and of resolving potential light echoes.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

10948 - REACQ(2,3,3) failed, scan step limit exceeded on FGS 2

REACQ(2,3,3) at 226/20:08:58 failed due to scan step limit exceeded on
FGS 2.

10949 - ACS 779 Fold Mechanism Move was Blocked

A series of ACS 779 Status Buffer Messages "Fold Mechanism Move Was
Blocked" were received beginning at 20:17:06. This was the result of a
failed REACQ(2,3,3) at 20:08:58 (HSTAR 10948) which caused the Take
Data Flag to be down when the fold mechanism move to the SBC position
was commanded.

COMPLETED OPS REQUEST:

18121-1 -* Patch WF2 UIDLE replacement htr set point, adjustment #4

COMPLETED OPS NOTES: None

*********************** SCHEDULED***** SUCCESSFUL
FGS GSacq************** 08***************** 08
FGS REacq************** 06***************** 05
OBAD with Maneuver **** 28***************** 28

SIGNIFICANT EVENTS:

The 4th in-flight adjustment of the WF/PC-II replacement heater
temperature control was successfully completed with the execution of
Ops Request 18121-1 at 226/14:07. All activities proceeded nominally.

The UIDLE dead band control range was shifted from 8.7 - 9.99 to 7.83
- 9.05 degC. The behavior of the replacement heaters under the control
of UIDLE and the optical bench temperatures will continue to be
monitored in real-time until such time as the new settings are
functionally verified. Another Flash Report will be sent following
this verification.

At 226/22:48:08 the replacement heaters were observed turning on when
Bay1 fell to 7.83 degs, ~ 7 minutes later they were disables when Bay1
reached 9.05 deg as expected, functionally verifying the patches.


 




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