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Daily Report # 4449



 
 
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Old September 18th 07, 05:06 PM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report # 4449

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***** # 4449

PERIOD COVERED: UT September 17, 2007 (DOY 260)

OBSERVATIONS SCHEDULED

WFPC2 10789

The Role of Environment in the Formation of Dwarf Galaxies

Clusters of galaxies contain an overdensity of dwarfs compared to the
field. Within galaxy clusters there is also a correlation between the
overdensity of dwarfs and local galaxy density, such that areas of
lower galaxy density contain more dwarfs per giant. The origin of
these 'extra' dwarfs is unknown, but a large fraction of them did not
form through standard collapses early in the universe. Some dwarf
ellipticals in clusters have metal rich and young { 6 Gyr} stellar
populations while others contain old metal poor populations,
suggesting multiple formation mechanisms and time scales. We propose
to test the idea that dwarfs descend from galaxies accreted into
clusters during the past 8 Gyr by correlating ages and metallicities
of dwarfs with their internal structures - spiral arms, bars, and
disks. If dwarfs originate from more massive galaxies then these
features should be common in metal rich and young dwarfs. On the other
hand, if no correlation is found it would suggest that dwarfs form
through in-situ collapses of gas in the intragalactic medium after
the
universe was reionized.

WFPC2 11027

Visible Earth Flats

This proposal monitors flatfield stability. This proposal obtains
sequences of Earth streak flats to construct high quality flat fields
for the WFPC2 filter set. These flat fields will allow mapping of the
OTA illumination pattern and will be used in conjunction with previous
internal and external flats to generate new pipeline superflats. These
Earth flats will complement the Earth flat data obtained during cycles
4-14.

WFPC2 11081

RR Lyrae stars in M31 Globular Clusters: How did the M31 Spiral Galaxy
Form?

The pulsation properties of the RR Lyrae stars in the globular
clusters of the Andromeda galaxy {M31} have the potential to provide
essential insight on the first epoch of the galaxy formation and to
trace the merging episodes that led to the assembly of M31. Their mean
periods along with the cluster metallicities can provide an
independent estimate of the M31 cluster ages and, in turn, of the time
scale of the M31 halo formation, by comparison with their Milky Way
counterparts. We will observe RR Lyrae stars in 6 appropriately
selected globular clusters of M31 using WFPC2 to derive periods, light
curves, and physical parameters of these eyewitnesses of the first
epochs of the M31 formation.

WFPC2 11084

Probing the Least Luminous Galaxies in the Local Universe

We propose to obtain deep color-magnitude data of eight new Local
Group galaxies which we recently discovered: Andromeda XI, Andromeda
XII, and Andromeda XIII {satellites of M31}; Canes Venatici I, Canes
Venatici II, Hercules, and Leo IV {satellites of the Milky Way}; and
Leo T, a new "free-floating" Local Group dwarf spheroidal with
evidence for recent star formation and associated H I gas. These
represent the least luminous galaxies known at *any* redshift, and are
the only accessible laboratories for studying this extreme regime of
galaxy formation. With deep WFPC-2 F606W and F814W pointings at their
centers, we will determine whether these objects contain single or
multiple age stellar populations, as well as whether these objects
display a range of metallicities.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of
Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens
a window into dynamical conditions in the protoplanetary disk where
they formed as well as the history of subsequent events which sculpted
the outer Solar System and emplaced them onto their present day
heliocentric orbits. To date, at least 47 TNBs have been discovered,
but only about a dozen have had their mutual orbits and separate
colors determined, frustrating their use to investigate numerous
important scientific questions. The current shortage of data
especially cripples scientific investigations requiring statistical
comparisons among the ensemble characteristics. We propose to obtain
sufficient astrometry and photometry of 23 TNBs to compute their
mutual orbits and system masses and to determine separate primary and
secondary colors, roughly tripling the sample for which this
information is known, as well as extending it to include systems of
two near-equal size bodies. To make the most efficient possible use of
HST, we will use a Monte Carlo technique to optimally schedule our
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 within 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: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

*********************** SCHEDULED***** SUCCESSFUL

FGS GSacq************** 06****************** 06
FGS REacq************** 08****************** 08
OBAD with Maneuver **** 30****************** 30

SIGNIFICANT EVENTS: (None)


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