This week on HST

HST Programs: November 18 - November 24, 2013

Program Number Principal Investigator Program Title
12880 Adam Riess, The Johns Hopkins University The Hubble Constant: Completing HST's Legacy with WFC3
12903 Luis C. Ho, Carnegie Institution of Washington The Evolutionary Link Between Type 2 and Type 1 Quasars
12920 Peter J. Wheatley, The University of Warwick Testing the paradigm of X-ray driven exoplanet evaporation with XMM+HST
12955 Pieter Deroo, Jet Propulsion Laboratory Comparing Planet Formation Signatures in two Systems
12956 Catherine Mary Huitson, University of Exeter The First Transmission Spectrum of an Eccentric Cool Jupiter
12963 Tracy Beck, Space Telescope Science Institute Spatially Resolving the Disk Mass Accretion Process In Young Star Binaries
13028 Evan D. Skillman, University of Minnesota - Twin Cities Is the First Epoch of Star Formation in Satellite Galaxies Universal?: M31 vs. Milky Way dSphs
13303 Robert A Simcoe, Massachusetts Institute of Technology The Structure of MgII Absorbing Galaxies at z=2-5: Linking CGM Physics and Stellar Morphology During Galaxy Assembly
13307 Nadia L Zakamska, The Johns Hopkins University Taking the measure of quasar winds
13309 Yicheng Guo, University of California - Santa Cruz UV Snapshot of Low-redshift Massive Star-forming Galaxies: Searching for the Analogs of High-redshift Clumpy Galaxies
13326 Ragnhild Lunnan, Harvard University Zooming In on the Progenitors of Ultra-Luminous Supernovae with HST
13332 Seth Redfield, Wesleyan University A SNAP Survey of the Local Interstellar Medium: New NUV Observations of Stars with Archived FUV Observations
13364 Daniela Calzetti, University of Massachusetts - Amherst LEGUS: Legacy ExtraGalactic UV Survey
13388 Gregory James Schwarz, American Astronomical Society Fundamental properties of novae outburst: Coordinated HST and XMM ToO observations
13389 Brian Siana, University of California - Riverside The Ultraviolet Frontier: Completing the Census of Star Formation at Its Peak Epoch
13397 Luciana C. Bianchi, The Johns Hopkins University Understanding post-AGB Evolution: Snapshot UV spectroscopy of Hot White Dwarfs
13404 William M. Grundy, Lowell Observatory Mutual Orbits and Physical Properties of Binary Transneptunian Objects
13467 Jacob L. Bean, University of Chicago Follow The Water: The Ultimate WFC3 Exoplanet Atmosphere Survey
13476 Nitya Kallivayalil, The University of Virginia Proper Motion and Internal Kinematics of the SMC: are the Magellanic Clouds bound to one another?
13481 Emily Levesque, University of Colorado at Boulder Calibrating Multi-Wavelength Metallicity Diagnostics for Star-Forming Galaxies
13483 Goeran Oestlin, Stockholm University eLARS - extending the Lyman Alpha Reference Sample
13490 Jason A. Surace, California Institute of Technology Resolving the Reddest Extragalactic Sources Discovered by Spitzer: Strange Dust-Enshrouded Objects at z~2-3?
13495 Jennifer Lotz, Space Telescope Science Institute HST Frontier Fields - Observations of Abell 2744

Selected highlights

GO 12903: The Evolutionary Link Between Type 2 and Type 1 Quasars

Artist's impression of the black hole and surrounding torus in an AGN
This year (2013) is the fiftieth anniversary of the recognition that QSOs (quasars, quasi-stellar objects) were extremely luminous objects lying at substantial redshifts. The central engine powering these luminous objects is now recognised as a supermassive black hole, marking the central regions of a galaxy. As such, QSOs are clearly related to (and more luminous than) active galactic nuclei (AGN). Like AGNs, QSOs have been segregated into two categories based on their spectral properties: systems with broad lines are characterised as Type 1 QSOs; systems with narrow lines are classed as Type 2. As with AGN, the underlying cause of these differences is generally believed to reside more in our perspective than on the sources themselves: heavily obscured systems, where the central accretion disk lies behind a thick veil of dust, are observed as Type 2 systems; they are expected to evolve to form Type 1 systems as the dust is ablated and destroyed. The present SNAP program aims to test this scenario by coupling mid-infrared Herschel observations, probing the dust environment, with HST near-infrared WFC3 imaging of targets drawn from two matched samples of Type 1 and Type 2 QSOs.

GO 12956: The First Transmission Spectrum of an Eccentric Cool Jupiter

Key events in a planetary transit
Transiting extrasolar planets offer particularly valuable insight into the detailed properties of planets in other stellar systems. Besides providing direct measures of mass (with no complications for v sin(i)) and radius (from accurate time-series photometry), spectroscopic observations obtained during either transit or planetary eclipse can probe the atmospheric structure and chemical composition. The results from those measurements can be used to test, and improve, theoretical models of extrasolar planets. These observations are best done from space: indeed, the only successful atmospheric observations to date have been with HST and Spitzer. Most attention has focused on the larger transiting planets, notably hot Jupiter systems like HD 209458b, HD 189733b, and HD 149026b. Recently, observations have turned towards a number of lower-mass hot Neptunes, such as Gl 436b and HAT-P-11b. In all of these systems, the transiting exoplanet lies relatievly close to the parent star, with the outer layers of the atmosphere reaching temperatuers of several thousand degress. The present program takes the ambitious step of moving towards transiting exoplanets at larger separations, and therefore with cooler atmospheric temperatures. The prime target is HAT-P-17b, a sub-Jovian-mass (0.53 MJ) planet in a ~10.3-day, relatuvely eccentric (e~0.34) orbit around a mid-type G dwarf lying at a distance of ~80-100 parsecs. The system also includes at least one other planet, a more massive (>1.2 MJ) object on a near-circulare 1794-day orbit. Stellar irradiation of the inner planet is likely to lead to atmospheric temperatures in the range ~630-950K. This program will use spectroscopic observation with STIS and WFC3 to probe the stellar spectrum during transits of the inner planet, and search for key elemental signatures at optical and near-infrared wavelengths.

GO 13476: Proper Motion and Internal Kinematics of the SMC: are the Magellanic Clouds bound to one another?

The Large Magellanic Cloud (upper left) with the Small Magellanic Cloud (right) and the (foreground) Galactic globular cluster47 Tucanae
The Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC) are the most massive satellites of the Milky Way galaxy. The orbital motions of these systems can be used to probe the mass distribution of Milky Way, and backtracking the orbits can shed light on how the three systems have interacted, In particular, the well known Magellanic Stream, stretching between the two Clouds, is thought to be a product either of interactions between the Clouds, or of ram-stripping of gas from the LMC on its last passage through the Plane of the Milky Way. Understanding the full scope of the interactions demands knowledge of the tangential motions of these systems - that is, proper motion measurements. Given the distances of the Clouds (~50 kpc.), the actual motions amount to only a few milliarcseconds, but the high spatial resolution and high stability of HST imaging makes such measurements possible. Past observing programs (eg GO 11730) have concentrated on the LMC, using the now-defunct ACS High Resolution Camera (ACS/HRC), the Planetary Camera on WFPC2 and the UVIS camera on WFC3 to target known QSOs lying behind the Clouds; the QSOs serve as fixed reference points for absolute astrometry of the numerous foreground LMC/SMC stars. The present program aims to build on those results by targeting 30 newly identified QSos behind the SMC for WFC3 observations ove a two-year span. The new observations should enable astronomers to not only refine the mean motion of the SMC, but also probe the internal rotation and velocity dispersion of stars in the Small Cloud.

GO 13495: HST Frontier Fields - Observations of Abell 2744

Pandora's Cluster, Abell 2744: the Chandra X-ray image, tracking hot gas, is plotted in red; the inferred dark matter distribution in blue
The overwhelming majority of galaxies in the universe are found in clusters. As such, these systems offer an important means of tracing the development of large-scale structure through the history of the universe. Moreover, as intense concentrations of mass, galaxy clusters provide highly efficient gravitational lenses, capable of concentrating and magnifying light from background high redshift galaxies to allow detailed spectropic investigations of star formation in the early universe. Hubble imaging has already revealed lensed arcs and detailed sub-structure within a handful of rich clusters. At the same time, the lensing characteristics provide information on the mass distribution within the lensing cluster. The present program builds on the highly successful CLASH program,which used 17-colour ACS/WFC3 images to map 25 galaxy clusters, tracing the mas profile and the dark matter distribution. in addition, the observations identified several lensed galaxies at redshifts that enter the JWST domaine, with the most distant object lying at a redshift z~11, within a few hundred million years of the Big Bang. The Frontier Fields program is a large-scale Director's Discretionary program that capitalises on the latter characteristic by targeting 4-6 strong-lensing galaxy clusters for very deep optical and near-infrared imaging. WFC3 and ACS will be used to observe the clusters, with simultaneous imaging obtained in parallel of a nearby "blank" field. Since the observations need to made at a specific orientation, they are being taken in two sets, ~6 months apart, alternating between detectors. Abell 2744, Pandora's Cluster, is the first target, with the cluster being imaged with WFC3-IR and the nearby blank field with ACS on the cluster field and WFC3-IR on the parallel field.

Past weeks:
page by Neill Reid, updated 14/10/2012
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