Status Report

NASA Hubble Space Telescope Daily Report #4176

By SpaceRef Editor
August 14, 2006
Filed under , ,
NASA Hubble Space Telescope Daily Report #4176

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT August 11,12,13, 2006 (DOY 223,224.225)


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 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.

FGS 10989

Astrometric Masses of Extrasolar Planets and Brown Dwarfs

We propose observations with HST/FGS to estimate the astrometric elements {perturbation orbit semi-major axis and inclination} of extra-solar planets orbiting six stars. These companions were originally detected by radial velocity techniques. We have demonstrated that FGS astrometry of even a short segment of reflex motion, when combined with extensive radial velocity information, can yield useful inclination information {McArthur et al. 2004}, allowing us to determine companion masses. Extrasolar planet masses assist in two ongoing research frontiers. First, they provide useful boundary conditions for models of planetary formation and evolution of planetary systems. Second, knowing that a star in fact has a plantary mass companion, increases the value of that system to future extrasolar planet observation missions such as SIM PlanetQuest, TPF, and GAIA.

ACS/HRC 10891

The Dynamical Mass of the Bright Cepheid Polaris

Cepheid variables are of central importance in Galactic and extragalactic astronomy. They are the primary standard candles for measuring extragalactic distances, and they provide critical tests of stellar-evolution theory. Surprisingly, however, until now there was not a single Cepheid with a purely dynamical measurement of its mass. Polaris {alpha UMi} is the nearest and brightest of all Cepheids. It offers the unique opportunity to measure the dynamical mass of a Cepheid, because it is in a binary system for which a single-lined spectroscopic orbit is already available. In Cycle 14, we resolved the system in the UV using ACS/HRC, thus providing the first direct detection of the companion, as well as a first approximation to the dynamical mass. In the present proposal we request one HST orbit per year for the next 3 Cycles, in order to refine the visual orbit. Combined with the HST/FGS parallax {see below}, this program will provide an accurate mass for the Cepheid {the error should be about 0.5 Msun by Cycle 17}, and the only one based purely on dynamical information. Only HST’s combination of high spatial resolution and UV sensitivity can achieve this result. The parallax is a key ingredient in the mass determination. In an ongoing multi-year program {GO-9888, GO-10113, GO-10482}, we are using the FGS to improve significantly upon the Hipparcos parallax of Polaris. The continued ACS imaging proposed here will thus provide extremely valuable astrophysical information from a very modest additional investment of observing time.

ACS/WFC 10880

The host galaxies of QSO2s: AGN feeding and evolution at high luminosities

Now that the presence of supermassive black holes in the nuclei of galaxies is a well established fact, other questions related to the AGN phenomena still have to be answered. Problems of particular interest are how the AGN gets fed, how the black hole evolves and how the evolution of the black hole is related to the evolution of the galaxy bulge. Here we propose to address some of these issues using ACS/WFC + F775W snapshot images of 73 QSO2s with redshifts in the range 0.3

ACS/WFC 10829

Secular Evolution at the End of the Hubble Sequence

The bulgeless disk galaxies at the end of the Hubble Sequence evolve at a glacial pace relative to their more violent, earlier-type cousins. The causes of their internal, or secular evolution are important because secular evolution represents the future fate of all galaxies in our accelerating Universe and is a key ingredient to understanding galaxy evolution in lower-density environments at present. The rate of secular evolution is largely determined by the stability of the cold ISM against collapse, star formation, and the buildup of a central bulge. Key diagnostics of the ISM’s stability are the presence of compact molecular clouds and narrow dust lanes. Surprisingly, edge-on, pure disk galaxies with circular velocities below 120 km/s do not appear to contain such dust lanes. We propose to obtain ACS/WFC F606W images of a well-selected sample of extremely late-type disk galaxies to measure the characteristic scale size of the cold ISM and determine if they possess the unstable, cold ISM necessary to drive secular evolution. Our sample has been carefully constructed to include disk galaxies above and below the critical circular velocity of 120 km/s where the dust properties of edge-on disks change so remarkably. We will then use surface brightness profiles to search for nuclear star clusters and pseudobulges, which are early indicators that secular evolution is at work, as well as measure the pitch angle of the dust lanes as a function of radius to estimate the central mass concentrations.

ACS/WFC 10816

The Formation History of Andromeda’s Extended Metal-Poor Halo

We propose deep ACS imaging in the outer spheroid of the Andromeda galaxy, in order to measure the star formation history of its true halo. For the past 20 years, nearly all studies of the Andromeda “halo” were focused on the spheroid within 30 kpc of the galaxy’s center, a region now known to host significant substructure and populations with high metallicity and intermediate ages. However, two groups have recently discovered an extended metal-poor halo beyond 30 kpc; this population is distinct in its surface-brightness profile, abundance distribution, and kinematics. In earlier cycles, we obtained deep images of the inner spheroid {11 kpc on the minor axis}, outer disk {25 kpc on the major axis}, and giant tidal stream, yielding the complete star formation history in each field. We now propose deep ACS imaging of 4 fields bracketing this 30 kpc transition point in the spheroid, so that the inner spheroid and the extended halo populations can be disentangled, enabling a reconstruction of the star formation history in the halo. A wide age distribution in the halo, as found in the inner spheroid, would imply the halo was assembled through ongoing accretion of satellite galaxies, while a uniformly old population would be a strong indication that the halo was formed during the early rapid collapse of the Andromeda proto-galaxy.

NIC2, ACS/WFC 10802

SHOES-Supernovae, HO, for the Equation of State of Dark energy

The present uncertainty in the value of the Hubble constant {resulting in an uncertainty in Omega_M} and the paucity of Type Ia supernovae at redshifts exceeding 1 are now the leading obstacles to determining the nature of dark energy. We propose a single, integrated set of observations for Cycle 15 that will provide a 40% improvement in constraints on dark energy. This program will observe known Cepheids in six reliable hosts of Type Ia supernovae with NICMOS, reducing the uncertainty in H_0 by a factor of two because of the smaller dispersion along the instability strip, the diminished extinction, and the weaker metallicity dependence in the infrared. In parallel with ACS, at the same time the NICMOS observations are underway, we will discover and follow a sample of Type Ia supernovae at z > 1. Together, these measurements, along with prior constraints from WMAP, will provide a great improvement in HST’s ability to distinguish between a static, cosmological constant and dynamical dark energy. The Hubble Space Telescope is the only instrument in the world that can make these IR measurements of Cepheids beyond the Local Group, and it is the only telescope in the world that can be used to find and follow supernovae at z > 1. Our program exploits both of these unique capabilities of HST to learn more about one of the greatest mysteries in science.

ACS/WFC 10794

Direct Age Determination of the dE Galaxies NGC 147 and NGC 185

Dwarf elliptical {dE} galaxies form some of the most numerous galaxies in the universe, yet their origins remain a mystery. The most popular formation scenarios are that dEs are either ancient, primordial objects, or the recent remnants of disrupted progenitor galaxies. These scenarios predict significantly different ratios of old and intermediate age stars. Stellar population characteristics can therefore discriminate between these scenarios. Previous spectroscopic work based on line strengths has had too many uncertainties to uniquely infer the stellar populations. Resolved color magnitude diagrams are needed instead. Since dE galaxies generally do not have stars younger than 1 Gyr, resolving the main sequence turnoff is required to directly quantify the star formation histories. Only ACS on HST can reach this depth, and it can only do so for the nearest two dE galaxies in the Local Group: the M31 dE satellites NGC 147 and NGC 185. Their main sequence turnoffs are expected to be at an apparent magnitude of V=29; we request F606W/F814W imaging one half magnitude fainter than this limit {and more than four magnitudes fainter than the deepest previous dE observations}. This will quantify the ratio of old to intermediate-age stars and will allow us to discriminate between the competing models of dE formation. On-going Keck/DEIMOS spectroscopy of several hundred red giant stars in each of these two dE galaxies, coupled with dynamical modeling and spectral synthesis, will complement the ACS measurement by providing information on chemical abundance patterns, dark matter content and internal dynamics. The proposed ACS data will be the first to directly quantify the onset and duration of star formation episodes in any dE galaxy. This measurement can only be done with HST/ACS, and it can only be done for these two galaxies in the dE class. This project will therefore be unique, and will be the most comprehensive study to date of any dE galaxy.


ACS CCDs daily monitor

This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. The files, biases and dark will be used to create reference files for science calibration. This programme will be for the entire lifetime of ACS. Changes from cycle 13:- The default gain for WFC is 2 e-/DN. As before bias frames will be collected for both gain 1 and gain 2. Dark frames are acquired using the default gain {2}. This program cover the period May, 31 2006- Oct, 1-2006. The first half of the program has a different proposal number: 10729.

ACS/HRC 10606

Ultraviolet Snapshots of 3CR Radio Galaxies

Radio galaxies are an important class of extragalactic objects: they are one of the most energetic astrophysical phenomena and they provide an exceptional probe of the evolving Universe, lying typically in high density regions but well-represented across a wide redshift range. In earlier Cycles we carried out extensive HST observations of the 3CR sources in order to acquire a complete and quantitative inventory of the structure, contents and evolution of these important objects. Amongst the results, we discovered new optical jets, dust lanes, face-on disks with optical jets, and revealed point-like nuclei whose properties support FR-I/BL Lac unified schemes. Here, we propose to obtain ACS NUV images of 3CR sources with z<0.3 as a major enhancement to an already superb dataset. We aim to reveal dust in galaxies, regions of star and star cluster formation frequently associated with dust and establish the physical characteristics of the dust itself. We will measure frequency and spectral energy distributions of point-like nuclei, seek spectral turnovers in known synchrotron jets and find new jets. We will strongly test unified AGN schemes and merge these data with existing X-ray to radio observations for significant numbers of both FR-I and FR-II sources. The resulting database will be an incredibly valuable resource to the astronomical community for years to come.

ACS/WFC 10592

An ACS Survey of a Complete Sample 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 ACS/WFC imaging 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, resolution, and field of view of ACS/WFC on HST enables a unique opportunity to study the detailed structure of galaxies that sample all stages of the merger process. Imaging will be done with the F439W and F814W filters {B and I-band} to examine as a function of both luminosity and merger state {i} the evidence at optical wavelengths of star formation and AGN activity and the manner in which instabilities {bars and bridges} in the galaxies may funnel material to these active regions, {ii} the relationship between star formation and AGN activity, and {iii} the structural properties {AGN, bulge, and disk components} and fundamental parameters {effective radius and surface brightness} of LIRGs and their similarity with putative evolutionary byproducts {elliptical, S0 and classical AGN host galaxies}. This HST survey will also bridge the wavelength gap between a Spitzer imaging survey {covering seven bands in the 3.6-160 micron range} and a GALEX UV imaging survey of these galaxies, but will resolve complexes of star clusters and multiple nuclei at resolutions well beyond the capabilities of either Spitzer or GALEX. The combined datasets will result in the most comprehensive multiwavelength study of interacting and merging galaxies to date.

ACS/WFC 10552

The distance of the Orion Nebula Cluster

The HST Treasury program on the Orion Nebula, currently in execution, has surprisingly found that background sources are easily detected by HST at long wavelengths through selected fields within the nebula. We propose to use these background sources as a reference system to measure the trigonometric parallax of the Orion Nebula cluster. Using ACS in the F850LP filter and with a modest investment of HST time, we will reduce the error on the ~500pc distance of the Orion Nebula to ~15pc, or less, improving by a factor ~6 over current estimates. Our new value will have a major impact on star formation studies, allowing to determine with high accuracy the absolute luminosity of the cluster members and all derived stellar parameters {ages, masses, mass accretion rates…}. Our current understanding of a great range of phenomena associated to the star formation activity in Orion will also benefit from an improved distance estimate.

ACS/HRC 10539

Coronagraphic Imaging of Bright New Spitzer Debris Disks

Fifteen percent of bright main sequence stars possess dusty circumstellar debris disks revealed by far-infrared photometry. These disks are signposts of planetary systems: collisions among larger, unseen parent bodies maintain the observed dust population against losses to radiation pressure and P-R drag. Images of debris disks at optical, infrared, and millimeter wavelengths have shown central holes, rings, radial gaps, warps, and azimuthal asymmetries which indicate the presence of planetary mass perturbers. Such images provide unique insights into the structure and dynamics of exoplanetary systems. Relatively few debris disks have been spatially resolved. Only nine have ever been resolved at any wavelength, and at wavelengths < 10 microns {where subarcsec resolution is available}, only seven: beta Pictoris, HR 4796, HD 141569, AU Mic, HD 107146, HD 92945, and Fomalhaut. Imaging of many other debris disk targets has been attempted with various HST cameras/coronagraphs and adaptive optics, but without success. The key property which renders a debris disk observable in scattered light is its dust optical depth. The seven disks imaged so far all have a dust excess luminosity >~ 0.01% that of the central star; no disks with smaller optical depths have been detected. Most main sequence stars known to meet this requirement have already been observed, so future progress in debris disk imaging depends on discovering additional stars with large infrared excess. The Spitzer Space Telescope offers the best opportunity in 20 years to identify new examples of high optical depth debris disk systems. We propose ACS coronagraphic imaging of nine bright, new debris disks uncovered during the first year of the Spitzer mission. Our goal is to obtain the first resolved images of these disks at ~3 AU resolution, define the disk sizes and orientations, and uncover disk substructures indicative of planetary perturbations. The results should double the number of debris disks observed at 0.06″ resolution, and open a wider window into the structure of planetary systems.

NIC2 10527

Imaging Scattered Light from Debris Disks Discovered by the Spitzer Space Telescope Around 20 Sun-like Stars

We propose to use the high contrast capability of the NICMOS coronagraph to image a sample of newly discovered circumstellar disks associated with sun-like stars. These systems were identified by their strong thermal infrared emission with the Spitzer Space Telescope as part of the Spitzer Legacy Science program titled, “The Formation and Evolution of Planetary Systems {FEPS}.” Modelling of the thermal excess emission in the form of spectral energy distributions alone cannot distinguish between narrowly confined high opacity disks and broadly distributed, low opacity disks. However, our proposed NICMOS observations can, by imaging the light scattered from this material. Even non- detections will place severe constraints on the disk geometry, ruling out models with high optical depth. Unlike previous disk imaging programs, our program contains a well defined sample of solar mass stars covering a range of ages from ~10Myrs to a few Gyrs, allowing us to study the evolution of disks from primordial to debris for the first time. These results will greatly improve our understanding of debris disks around Sun- like stars at stellar ages nearly 10x older than any previous investigation. Thus we will have fit a crucial piece into the puzzle concerning the formation and evolution of our own solar system.

NIC1 10517

Imaging Astrometrically-Discovered Brown Dwarfs

We propose to image the astrometrically discovered companions of three M-dwarfs with NICMOS to more tightly constrain their masses and determine their stellar or sub-stellar natures. Each of these systems has been observed with a sensitive ground-based adaptive optics system and no companions have been detected. NICMOS results will eliminate an ambiguity in the astrometric mass measurements that arises because a companion that contributes significantly to the visible light reduces the motion of the center of light and mimics a small motion of the center of mass. In addition the astrometric measurements made with NICMOS will fix the scale of the system, distinguishing among possible orbits. Finally the color photometry will constrain the spectral types to within a couple of subtypes. When we measure the masses of astrophysical objects, we test and assist the development of the theoretical mass models. Models are based upon parameters such as age and metallicity. Determining the correct mass thus deepens our understanding of the fundamental physics of stars and substellar objects

NIC2 10510

Morphology of massive early-type galaxies at z>1.2: constraining galaxy formation models

We ask for NICMOS-NIC2 H-band imaging of a sample of 10 massive early-type galaxies spectroscopically identified at 1.26500A, would map the mass distribution of the bulk of their stellar content. The targets have been revealed by our group on the basis of near-IR spectroscopy obtained in the framework of a spectroscopic survey of a complete sample of bright EROs {Ks<18.5}. Optical and near-IR photometry is available for all the targets, and low resolution near-IR spectra have allowed their identification and redshift measurement. Spectroscopic and photometric data in our hands show that they have already assembled stellar masses greater than 3 10^11 solar masses, and that the mean age of their stellar population is estimated older than 2-3 Gyr for 6 of them and about 1 Gyr for the other 4 galaxies. Thus, they are among the most luminous and massive evolved galaxies detected so far at z>1. Other data are needed to infer how they have assembled such high stellar masses, i.e. to trace back their evolution. The requested observations would allow us to reveal signs of past interaction/merger event. A smooth r^{1/m} profile, coupled with no other signs of interaction/merger {disturbed morphology}, would place the possible merger event of formation 1-2 Gyr before their redshift z pprox 1.5, i.e. at z > 2-3. On the other hand, if signs of recent merger events will be found, the last merger event forming the local massive spheroids will be constrained at 1.5 < z < 2. Thus, the requested HST observations will allow for the first time to see how massive early-type galaxies at z pprox 1.5 look like, constraining in any case the redshift of the possible merging event of their formation.

ACS/WFC/NIC2 10496

Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters

We propose a novel HST approach to obtain a dramatically more useful “dust free” Type Ia supernovae {SNe Ia} dataset than available with the previous GOODS searches. Moreover, this approach provides a strikingly more efficient search-and-follow-up that is primarily pre- scheduled. The resulting dark energy measurements do not share the major systematic uncertainty at these redshifts, that of the extinction correction with a prior. By targeting massive galaxy clusters at z > 1 we obtain a five-times higher efficiency in detection of Type Ia supernovae in ellipticals, providing a well-understood host galaxy environment. These same deep cluster images then also yield fundamental calibrations required for future weak lensing and Sunyaev-Zel’dovich measurements of dark energy, as well as an entire program of cluster studies. The data will make possible a factor of two improvement on supernova constraints on dark energy time variation, and much larger improvement in systematic uncertainty. They will provide both a cluster dataset and a SN Ia dataset that will be a longstanding scientific resource.


A Search for Debris Disks in the Coeval Beta Pictoris Moving Group

Resolved observations of debris disks present us with the opportunity of studying planetary evolution in other solar systems. We propose to search for debris disks in the Beta Pictoris moving group {8-20 Myrs, 10-50 pc away} , which provides a coeval sample of multiple spectral types, and it has already produced two magnificent resolved debris disks: AU Mic and Beta Pic. Such coeval sample will provide us with a snapshop of the crucial time in disk evolution in which the disk makes the transition from optically thick to optically thin, and it will be useful to study the stellar mass dependence of the disk evolution.


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


10399 – SA Section 5 Current Anomaly

With the -BB SPA temporarily off-line, the SA Section 5 current should go to 0 when Battery 5 reaches charge cut-off. Since approximately 222 / 16:00, the SA section 5 current indicates 1.8A after battery 5 reaches charge cut-off. The anomalous current is not fully seen in the Structure current (less than 0.2A increase).

10400 – GSacq(2,3,2) failed to RGA control @225/1642z

Only QF2STOPF and QSTOP flags were set. OBADs respective RSS values were 2863.99 & 7.50. OBAD MAP at 16:53:36 showed an RSS value of 15.17



                         SCHEDULED      SUCCESSFUL 
FGS GSacq               28                    27 
REacq               16                    16 

OBAD with Maneuver 88 88


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