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 # 4433
PERIOD COVERED: UT August 23, 2007 (DOY 235)
OBSERVATIONS SCHEDULED
WFPC2 10787
Modes of Star Formation and Nuclear Activity in an Early
Universe
Laboratory
Nearby compact galaxy groups are uniquely suited to
exploring the
mechanisms of star formation amid repeated and ongoing
gravitational
encounters, conditions similar to those of the high redshift
universe.
These dense groups host a variety of modes of star formation, and
they
enable fresh insights into the role of gas in galaxy evolution.
With
Spitzer mid-IR observations in hand, we have begun to obtain
high
quality, multi-wavelength data for a well- defined sample of 12
nearby
{<4500km/s} compact groups covering the full range of
evolutionary
stages. Here we propose to obtain sensitive BVI images with the
ACS/WFC,
deep enough to reach the turnover of the globular cluster
luminosity
function, and WFPC2 U-band and ACS H-alpha images of
Spitzer-identified
regions hosting the most recent star formation. In total,
we expect to
detect over 1000 young star clusters forming inside and
outside
galaxies, more than 4000 old globular clusters in >40 giant
galaxies
{including 16 early-type galaxies}, over 20 tidal
features,
approximately 15 AGNs, and intragroup gas in most of the 12
groups.
Combining the proposed ACS images with Chandra observations, UV
GALEX
observations, ground-based H-alpha imaging, and HI data, we will
conduct
a detailed study of stellar nurseries, dust, gas kinematics, and AGN.
WFPC2 10901
UV-Luminous Globular Clusters in NGC 1399
Ultraviolet observations have revealed remarkable
diversity among old
stellar populations in globular clusters and E/S0
galaxies. We recently
discovered with HST/STIS that globular clusters in the
giant elliptical
galaxy M87 have the most heavily populated hot horizontal
branches of
any stellar systems yet studied. Their far-UV/optical colors are
up to 1
mag bluer than any Milky Way globular cluster and approach
the
theoretical limits for production of hot-HB stars in old
stellar
populations. The differences among the metal-poor clusters
are
particularly interesting, because it is thought that these
objects
reflect the earliest stages of galaxy formation at high redshifts.
Here
we propose deep ACS far-UV imaging of a second gE galaxy, NGC 1399,
with
a cluster system that is well-studied at longer wavelengths,
to
determine whether it shares characteristics with M87. These
observations
bear on aspects of advanced stellar evolution, on the histories
of
globular clusters in different environments, and on the
interpretation
of the "ultraviolet upturn'' phenomenon in elliptical galaxies
and its
value as a population probe in distant galaxies.
WFPC2 11039
Polarizers Closeout
Observations of standard stars and a highly polarized
reflection nenula
are made as a final calibration for the WFPC2 polarizers.
VISFLATS are
also obtained.
WFPC2 11291
Following Eta Carinae's Change of State
Eta Carinae is now known to be undergoing some unusually
rapid changes
on a timescale of several years. They are probably essential
for
modeling the star's long-term recovery from its Giant Eruption 160
years
ago -- the prototype "supernova impostor" event. Since high
spatial
resolution is needed to isolate the central star, and the present
state
will probably not recur in the future, it is important to obtain
HST
data during the next two years. We propose a cost-effective set of
ACS
observations with three goals: {1} to obtain a continuing record of
the
star's rapid UV and visual brightening; {2} to lengthen the
temporal
baseline of ACS images enough to settle an important question
concerning
ejecta ages; and {3} to extend the record of morphological changes
in
the inner ejecta past the midpoint of eta Car's 5.5-year cycle.
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
28
28
SIGNIFICANT EVENTS: (None)