This week on HST


HST Programs: April 25 - May 1, 2016

Program Number Principal Investigator Program Title
14037 Jennifer Lotz, Space Telescope Science Institute HST Frontier Fields - Observations of Abell S1063
14060 Roberto Soria, Curtin University A huge ULX bubble in NGC 5585
14066 Angela Adamo, Stockholm University Hi-PEEC, Hubble imaging Probe of Extreme Environments and Clusters
14069 Nate Bastian, Liverpool John Moores University Searching For Multiple Populations in Massive Young and Intermediate Age Clusters
14074 Roger Cohen, Universidad de Concepcion Opening the Window on Galaxy Assembly: Ages and Structural Parameters of Globular Clusters Towards the Galactic Bulge
14075 Ori Dosovitz Fox, Space Telescope Science Institute Long-Lost Companions: A Search for the Binary Secondaries of Three Nearby Supernovae
14095 Gabriel Brammer, Space Telescope Science Institute - ESA Calibrating the Dusty Cosmos: Extinction Maps of Nearby Galaxies
14096 Dan Coe, Space Telescope Science Institute - ESA RELICS: Reionization Lensing Cluster Survey
14098 Harald Ebeling, University of Hawaii Beyond MACS: A Snapshot Survey of the Most Massive Clusters of Galaxies at z>0.5
14100 Kevin France, University of Colorado at Boulder A Direct Imaging Experiment to Determine the Origin of H2 Emission from M dwarf Exoplanetary Systems
14131 Ivana Orlitova, Astronomical Institute, Academy of Sciences of CR Origin of double peaks in Lyman-alpha spectra: diffuse halos or Lyman continuum leakage?
14138 Kohji Tsumura, FRIS, Tohoku University Absolute Measurement of the Cosmic Near-Infrared Background Using Eclipsed Galilean Satellites as Occulters
14141 Guy Worthey, Washington State University NGSL Extension 1. Hot Stars and Evolved Stars
14161 Ruth C. Peterson, SETI Institute The Intersection of Atomic Physics and Astrophysics: Identifying UV Fe I Lines from Metal-Poor Turnoff Stars
14163 Mickael Rigault, Humboldt Universitat zu Berlin Honing Type Ia Supernovae as Distance Indicators, Exploiting Environmental Bias for H0 and w.
14178 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey: The WISP Deep Fields
14199 Patrick Kelly, University of California - Berkeley Refsdal Redux: Precise Measurements of the Reappearance of the First Supernova with Multiple Resolved Images
14209 Brian Siana, University of California - Riverside The Final UV Frontier: Legacy Near-UV Imaging of the Frontier Fields
14212 Karl Stapelfeldt, Jet Propulsion Laboratory A Snapshot Imaging Survey of Spitzer-selected Young Stellar Objects in Nearby Star Formation Regions*.t23
14227 Casey Papovich, Texas A & M University The CANDELS Lyman-alpha Emission At Reionization (CLEAR) Experiment
14235 Sangmo Tony Sohn, The Johns Hopkins University Globular Cluster Orbits from HST Proper Motions: Constraining the Formation and Mass of the Milky Way Halo
14240 Bart P. Wakker, University of Wisconsin - Madison Mapping the circumgalactic medium of two large spiral galaxies
14251 Amy E. Reines, National Optical Astronomy Observatory, AURA The Structures of Dwarf Galaxies Hosting Massive Black Holes
14269 Nicolas Lehner, University of Notre Dame Just the BASICs: Linking Gas Flows in the Circumgalactic Medium to Galaxies
14327 Saul Perlmutter, University of California - Berkeley See Change: Testing time-varying dark energy with z>1 supernovae and their massive cluster hosts
14351 Laura Chomiuk, Michigan State University The Black Hole Population in Galactic Globular Clusters
14480 Wolf-Rainer Hamann, Universitat Potsdam Joint XMM-Newton and HST study of the magnetic weak-wind O-star HD 54879
14487 Ben E. K. Sugerman, Goucher College Light Echoes and the Progenitor of SN 2016adj in Cen A

Selected highlights

GO 14069: Searching For Multiple Populations in Massive Young and Intermediate Age Clusters


HST image of the LMC cluster, NGC 1866
Globular clusters are remnants of the first substantial burst of star formation in the Milky Way. With typical masses of a few x 105 solar masses, distributed among several x 106 stars, the standard picture holds that these are simple systems, where all the stars formed in a single starburst and, as a consequence, have the same age and metallicity. Until recently, the only known exception to this rule was the cluster Omega Centauri, which is significantly more massive than most clusters and has both double main sequence and a range of metallicities among the evolved stars. Over the past 5-10 years, Omega Cen has been joined by numerous other Galactic clusters, including NGC 2808, which shows evidence for three distinct branches to the main sequence, NGC 1851, 47 Tucanae and NGC 6752 - all relatively massive clusters. In almost all cases, the complexity of these systems has only emerged through the high precision observations possible with HST. Hubble is now being turned towards clusters in our nearest neighbour galaxies, the Large and Small Magellanic Clouds. Previousl observations have obtained of the massive cluster NGC 1846. The present program aims to extends coverage to a dozen other clusters, including NGC 419, 1783, 1850 and 1866. The clusters span a wide range of ages, from ~100 Myrs to close to 10 Gyrs. The WFC3-UVIS camera will be used to obtain UV (F343N, F336W) and blue-band (F438W) images to search for evidence of multiple populations in the colour-magnitude diagrams.

GO 14096: RELICS: Reionization Lensing Cluster Survey


Hubble image and mass map for the cluster ACT-CL J0102-4915, one of the clusters included in the RELICS program
The overwhelming majority of galaxies in the universe are found in clusters. As such, those 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, and the Frontier Fields program, targeting six clusters for deep multi-colour imaging. RELICS is focused on using massive galaxy clusters as gravitational telescopes, searching for strongly lensed background galaxies drawn from the high redshift universe. Imaging 46 fields in 41 galaxy clusters, this program aims to identify galaxies with redshifts in the range 9 < z < 12. By targeting strongly-lensing clusters, standard models for galaxy evolution suggest that the program can deliver ~100 galaxies in that redshift range, together with more than 150 galaxies at z~8. A significant number of these galaxies should be brighter than H~25.5, and therefore accessible to more detailed follow-up observations. Conversely, the actual number of galaxies detected will set constraints on the galaxy number-redshift distribution, and the overall formation and assembly history.

GO 14138: Absolute Measurement of the Cosmic Near-Infrared Background Using Eclipsed Galilean Satellites as Occulters


Jupiter and the Galilean satellite Ganymede
The Cosmic Infrared Background is generally conjectured to represent the diffuse, redshifted light from star formation early in the post-recombination Universe. It provides an important link between the resolved structure that we see today and the primordial fluctuations measured by the cosmic mcirowave background. Measuring the CIB, however, is not a straightforward task, since there are several other sources of infrared radiation that dominate the measured fluxes, notably stars at near-infrared wavelengths, the zodiacal light at mid-infrared wavelengths and emission from Galactic cirrus in the far infrared. The present program proposes a novel mean of isolating the near-infrared contribution from one of those components, the zodiacal light. The WFC3 IR camera will be used to observe the two of the Galilean satellites during the period when they have entered the jovian shadow, and are therefore under a solar eclipse, but are still visible from Earth. The overwhelming majority of the zodiacal light is contributed by scattered light from dust particles between us and Jupiter; the Galilean satellites obscure any contribution to the near-infrared background from sources that lie beyond Jupiter's orbit, including contributions from the CIB. If the latter contributions are significant, then one would expect to see reduced flux (ie dark spots) in the satellite locations. The present observations target Europa and Ganymede during eclipse.

GO 14199: Refsdal Redux: Precise Measurements of the Reappearance of the First Supernova with Multiple Resolved Image


Finding chart for the multiply imaged supernova, SN Refsdal, discovered in November 2014 in cluster MACJ1149
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, providing information on the mass distribution within the lensing cluster. Over the past three cycles, Hubble has been undertaking deep imaging observations 6 galaxy clusters as the Frontier Fields Director's Time program (GO 13495/13496). Those observations have provided a basis for several synergistic programs. In particular, the observations enabled a search for supernovae at high redshifts, z> 1.5, aiming to set further constraints on dark energy and probing the frequency of supernovae as a function of redshift, the delay time and hence the likely progenitors.
In 2014, observations of the fourth cluster, MACSJ1149.5+2223, resulted in the detection of a particularly unusual object - multiple lensed images of a supernova in a redshift z=1.49 galaxy that is itself multiply lensed. Each of those images results from light following a different path due to the gravitational potential of the foreground cluster and galaxies. Dubbed Supernova Refsdahl, after the gravitational lensing pioneer, the original detections were followed over the course of their fading. But, more spectacularly, models of the cluster potential and the consequent light paths led to a prediction that the supernova should appear in one of the other lensed images of the parent galaxy in late 2015. The present program set out to check those predictions by re-imaging the cluster.
Update: the supernova was not present in observations obtained on November 14, 2015, but has been detected in the December 11 observations, thus representing the first time that a supernova has been "predicted" successfully.Further observations are being obtained to monitor the light curve.

Past weeks:
page by Neill Reid, updated 23/12/2014
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