NASA Hubble Space Telescope Daily Report # 4591
HUBBLE SPACE TELESCOPE DAILY REPORT # 4591
Continuing to collect World Class Science
PERIOD COVERED: UT April 16, 2008 (DOY 107)
OBSERVATIONS SCHEDULED
ACS/SBC/WFPC2 11230
HST FUV Observations of Brightest Cluster Galaxies: The Role of Star Formation in Cooling Flows and BCG Evolution
The intracluster medium (ICM) now appears to be a very dynamic place where heating and cooling processes vie for dominance and an uneasy equilibrium is maintained. Since these same processes may operate during the process of galaxy formation, the centers of clusters of galaxies provide low redshift laboratories for studying the critical processes involved in galaxy formation and black hole growth. At the present time, the main questions are (1) How much gas is cooling out of the ICM? (2) How much star formation is ongoing? (3) What is the impact of the gas and star formation on the central BCG? In order to measure the current star formation in BCGs we have undertaken a program of Spitzer IRAC and MIPS observations. We are in process of obtaining observations of a sample of Brightest Cluster Galaxies in 70 clusters selected from the ROSAT all sky survey. In about 25% of the sources observed so far, we detect a mid-IR excess which we attribute to dust heated by star formation. We propose to obtain ACS/SBC observations of the Lyman Alpha emission line and the adjacent FUV continuum in 7 BCGs which are in cooling core clusters of galaxies and have a large mid-IR excess. We also propose WFPC2 F606W observations of the two clusters without high resolution imaging to allow us to image the dust on the same scale as the Far UV continuum. The FUV will allow us to confirm the presense of ongoing starformation in these BCGs and will allow us to rule out an AGN as the dominant contributer to the mid-IR. The morphology and spatial extent of the young stars and the heated dust and CO will constrain the spatial scale over which star formation occurs and thus where the cooling gas is deposited. The combination of our FUV and IR observations will allow us to estimate the star formation rates which must balance the rate at which cold gas is deposited in the BCG. Our proposed FUV observations will produce unique information about the cooling gas, the true mass accretion rates, and the star formation rates in BCGs and its effect on the galaxy.
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA calibration – CR Persistence Part 6
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 DARKSs. 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.
NIC3 11120
A Paschen-Alpha Study of Massive Stars and the ISM in the Galactic Center
The Galactic center (GC) is a unique site for a detailed study of a multitude of complex astrophysical phenomena, which may be common to nuclear regions of many galaxies. Observable at resolutions unapproachable in other galaxies, the GC provides an unparalleled opportunity to improve our understanding of the interrelationships of massive stars, young stellar clusters, warm and hot ionized gases, molecular clouds, large scale magnetic fields, and black holes. We propose the first large-scale hydrogen Paschen alpha line survey of the GC using NICMOS on the Hubble Space Telescope. This survey will lead to a high resolution and high sensitivity map of the Paschen alpha line emission in addition to a map of foreground extinction, made by comparing Paschen alpha to radio emission. This survey of the inner 75 pc of the Galaxy will provide an unprecedented and complete search for sites of massive star formation. In particular, we will be able to (1) uncover the distribution of young massive stars in this region, (2) locate the surfaces of adjacent molecular clouds, (3) determine important physical parameters of the ionized gas, (4) identify compact and ultra-compact HII regions throughout the GC. When combined with existing Chandra and Spitzer surveys as well as a wealth of other multi-wavelength observations, the results will allow us to address such questions as where and how massive stars form, how stellar clusters are disrupted, how massive stars shape and heat the surrounding medium, and how various phases of this medium are interspersed.
WFPC2 11125
The Dynamical Evolution of Globular Clusters
Globular clusters evolve through dynamical interactions, with primordial binaries extending the time until core collapse by up to an order of magnitude, depending on the initial binary fraction. These dynamical interactions plus mass segregation causes the binary fraction to rise in the core but fall at larger radii. We hope to eventually test these broad predictions by comparing them to the binary properties for globular clusters at different states of evolution, defined by the ratio of their age to the dynamical relaxation time at the half-light radius. The most important unknown aspects in the modeling process are the initial conditions of binaries in the cluster. Here we propose to determine the initial binary fraction as a function of radius by studying three of the dynamically youngest globular clusters {NGC 5053, NGC 5466, and NGC 5897}. The presence of binaries thickens the Main Sequence in a color-magnitude diagram, which can be detected with deep multicolor images.
WFPC2 11130
AGNs with Intermediate-mass Black Holes: Testing the Black Hole-Bulge Paradigm, Part II
The recent progress in the study of central black holes in galactic nuclei has led to a general consensus that supermassive {10^6-10^9 solar mass} black holes are closely connected with the formation and evolutionary history of large galaxies, especially their bulge component. Two outstanding issues, however, remain unresolved. Can central black holes form in the absence of a bulge? And does the mass function of central black holes extend below 10^6 solar masses? Intermediate-mass black holes {<10^6 solar masses}, if they exist, may offer important clues to the nature of the seeds of supermassive black holes. Using the SDSS, our group has successfully uncovered a new population of AGNs with intermediate-mass black holes that reside in low-luminosity galaxies. However, very little is known about the detailed morphologies or structural parameters of the host galaxies themselves, including the crucial question of whether they have bulges or not. Surprisingly, the majority of the targets of our Cycle 14 pilot program have structural properties similar to dwarf elliptical galaxies. The statistics from this initial study, however, are really too sparse to reach definitive conclusions on this important new class of black holes. We wish to extend this study to a larger sample, by using the Snapshot mode to obtain WFPC2 F814W images from a parent sample of 175 AGNs with intermediate- mass black holes selected from our final SDSS search. We are particularly keen to determine whether the hosts contain bulges, and if so, how the fundamental plane properties of the host depend on the mass of their central black holes. We will also investigate the environment of this unique class of AGNs.
WFPC2 11132
Constraining the age of the AB Dor system
The zero-age main sequence K-type star AB Dor, with an age of 25 to 125 Myr, is the most active young star in the solar neighbourhood. It is part of a quadruple system of young stars. The mass of AB Dor C, the closest and lowest mass companion, has been derived from astrometric observations (with the VLA and adaptive optics at the VLT) to 94+-3 times the mass of Jupiter. The low mass (close to the hydrogen burning limit) combined with the young age makes AB Dor C a unique calibration source for evolutionary tracks for very low-mass stars and brown dwarfs, provided that a precise age estimate can be derived for the system. We propose to use the HST planetary camera to obtain resolved component photometry of the M-type pre-main sequence star AB Dor Ba and Bb in order to derive individual spectral types and luminosities, which will enable us to age-date the AB Dor system to better than +-20 Myr. In addition, the observations will help to constrain the Ba/Bb orbit, and hence to derive dynamical mass estimates as well.
WFPC2 11235
HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in the Local Universe
At luminosities above 10^11.4 L_sun, the space density of far-infrared selected galaxies exceeds that of optically selected galaxies. These `luminous infrared galaxies’ {LIRGs} are primarily interacting or merging disk galaxies undergoing enhanced star formation and Active Galactic Nuclei {AGN} activity, possibly triggered as the objects transform into massive S0 and elliptical merger remnants. We propose NICMOS NIC2 imaging of the nuclear regions of a complete sample of 88 L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised Bright Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}. This sample is ideal not only in its completeness and sample size, but also in the proximity and brightness of the galaxies. The superb sensitivity and resolution of NICMOS NIC2 on HST enables a unique opportunity to study the detailed structure of the nuclear regions, where dust obscuration may mask star clusters, AGN and additional nuclei from optical view, with a resolution significantly higher than possible with Spitzer IRAC. This survey thus provides a crucial component to our study of the dynamics and evolution of IR galaxies presently underway with Wide-Field, HST ACS/WFC and Spitzer IRAC observations of these 88 galaxies. Imaging will be done with the F160W filter {H-band} to examine as a function of both luminosity and merger stage {i} the luminosity and distribution of embedded star clusters, {ii} the presence of optically obscured AGN and nuclei, {iii} the correlation between the distribution of 1.6 micron emission and the mid- IR emission as detected by Spitzer IRAC, {iv} the evidence of bars or bridges that may funnel fuel into the nuclear region, and {v} the ages of star clusters for which photometry is available via ACS/WFC observations. The NICMOS data, combined with the HST ACS, Spitzer, and GALEX observations of this sample, will result in the most comprehensive study of merging and interacting galaxies to date.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
11255 – GSAcq(2,1,2) failed to RGA Hold (Gyro Control)
Upon acquisition of siganl at 107/16:22:31, the GSAcq(2,1,2) scheduled at 107/15:08:24 – 15:16:29 failed to RGA Hold due to (QF1STOPF) stop flag indication on FGS-1. Pre-acquisition OBADs (RSS) attitude correction values are not available due to LOS. Post-acq OBAD/MAP had (RSS) value of 1373.29 arcseconds.
COMPLETED OPS REQUEST:
18225-0 – Modify RWA Spin Down Estimate Parameters @107/1314z 18054-0 – Preview KF Sun Vector Data via Telemetry Diags @107/1321z
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 08 07
FGS REacq 04 04
OBAD with Maneuver 24 24
SIGNIFICANT EVENTS: (None)
