This week on HST

HST Programs: November 21 - November 27, 2016

Program Number Principal Investigator Program Title
14096 Dan Coe, Space Telescope Science Institute - ESA RELICS: Reionization Lensing Cluster Survey
14114 Pieter van Dokkum, Yale University A Wide-Field WFC3 Imaging Survey in the COSMOS Field
14120 Jarle Brinchmann, Universiteit Leiden He II emission as a tracer of ultra-low metallicity and massive star evolution
14178 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey: The WISP Deep Fields
14182 Thomas H. Puzia, Pontificia Universidad Catolica de Chile The Coma Cluster Core Project
14216 Robert P. Kirshner, Harvard University RAISIN2: Tracers of cosmic expansion with SN IA in the IR
14219 John P. Blakeslee, Dominion Astrophysical Observatory Homogeneous Distances and Central Profiles for MASSIVE Survey Galaxies with Supermassive Black Holes
14235 Sangmo Tony Sohn, Space Telescope Science Institute Globular Cluster Orbits from HST Proper Motions: Constraining the Formation and Mass of the Milky Way Halo
14343 Nitya Kallivayalil, The University of Virginia Proper Motion and Internal Kinematics of the SMC: are the Magellanic Clouds bound to one another?
14493 Vincent Bourrier, Observatoire de Geneve UV exploration of two Earth-sized planets with temperate atmospheres
14594 Rich Bielby, Durham Univ. QSAGE: QSO Sightline And Galaxy Evolution
14606 Brooke Devlin Simmons, University of California - San Diego Secular Black Hole Growth and Feedback in Merger-Free Galaxies
14618 Michael Shara, American Museum of Natural History Ultraviolet Flashers in M87: Rapidly Recurring Novae as SNIa Progenitors
14653 James Lowenthal, Smith College The most luminous galaxies: strongly lensed SMGs at 1
14664 Thomas G. Beatty, The Pennsylvania State University Phase-Resolved Emission Spectroscopy of the Transiting Brown Dwarf KELT-1b Using WFC3
14675 Julia Christine Roman-Duval, Space Telescope Science Institute - ESA Metal Evolution and TrAnsport in the Large Magellanic Cloud (METAL): Probing Dust Evolution in Star Forming Galaxies
14682 Bjoern Benneke, California Institute of Technology A Search for Methane, Ammonia, and Water on Two Habitable Zone Super-Earths
14701 Michele Trenti, University of Melbourne Is galaxy formation different during the epoch of reionization? Confirmation of the brightest ever candidate at redshift z>8
14704 Charlie Conroy, Harvard University A Year in the Whirlpool
14729 Rajib Ganguly, University of Michigan A New Twist in the Quasar Radio Dichotomy: The Case of the Missing Outflows
14762 Justyn Robert Maund, University of Sheffield A UV census of the sites of core-collapse supernovae
14766 Joshua D. Simon, Carnegie Institution of Washington ACS Imaging of the Ultra-Faint Dwarf Galaxy Reticulum II: Age-Dating a Unique Nucleosynthetic Event
14776 Trent J. Dupuy, University of Texas at Austin Mapping the Substellar Mass-Luminosity Relation Down to the L/T Transition
14778 Douglas Russell Gies, Georgia State University Research Foundation Hiding in Plain Sight: The Low Mass Helium Star Companion of EL CVn
14779 Melissa Lynn Graham, University of Washington A NUV Imaging Survey for Circumstellar Material in Type Ia Supernovae
14786 Benjamin F. Williams, University of Washington Progenitor Masses for Every Nearby Historic Core-Collapse Supernova
14793 Jacob L. Bean, University of Chicago The First Precise Atmospheric Metallicity Measurement for a Sub-Jovian Exoplanet
14862 Ariel Goobar, Stockholm University Resolving the multiple images of the strongly lensed SNIa iPTF16geu

Selected highlights

GO 14178: WISP - A Survey of Star Formation Across Cosmic Time

A region of massive star formation
Star formation is the key astrophysical process in determining the overall evolution of galactic systems, the generation of heavy elements, and the overall enrichment of interstellar and intergalactic material. Tracing the overall evolution through a wide redshift range is crucial to understanding how gas and stars evolved to form the galaxies that we see around us now. The present program builds on the ability of HST to carry out parallel observations, using more than one instrument. While the Cosmic Origins Spectrograph is focused on obtaining ultraviolet spectra of unparalleled signal-to-noise, this program uses the near-infrared grisms mounted on the Wide-Field Camera 3 infrared channel to obtain low resolution spectra between 1 and 1.6 microns of randomly-selected nearby fields. The goal is to search for emission lines characteristic of star-forming regions. In particular, these observations are capable of detecting Lyman-alpha emission generated by star formation at redshifts z > 5.6. A total of up to 40 "deep" (4-5 orbit) and 20 "shallow" (2-3 orbit) fields will be targeted in the course of this observing campaign.

GO 14235: Globular Cluster Orbits from HST Proper Motions: Constraining the Formation and Mass of the Milky Way Halo

Hubble image of the metal-poor globular cluster, M15
Globular clusters are members of the Galactic halo population, representing remnants from the first extensive period of star formation in the Milky Way. As such, the properties of the 106 to 107 stellar constituents can provide crucial insight into the earliest stages of galaxy formation. Until recently, conventional wisdom was that these are simple systems, where all the stars formed in a single starburst and, as a consequence, have the same age and metallicity. One of the most surprising disoveries in recent years is the realisation that this simple picture no longer holds. A substantial number of thee systems show complex structure in the colour-magnitude diagram, indicating the presence ofmultiple stellar populations. Current globulars may therefore represent the remnant cores of dwarf galaxy-like systems. Regardless of their origin, the present systems can also serve to map the potential of the Milky Way. Undertaking that analysis demands the determination of three-dimensional motions, requiring that we obtain accurate absolute proper motions for these systems. That is now becoming possible; thanks to Hubble's longevity, a significant number of clusters have imaging data from 10-20 years ago. Coupled with new observations, those data provide the baseline to allow measurement of the tranverse motion, and hence orbit determinations.

GO 14776: Mapping the Substellar Mass-Luminosity Relation Down to the L/T Transition

Epsilon Indi Bab, the binary brown dwarf companion of the nearby K dwarf
Brown dwarfs are objects that form like stars, but lack sufficient mass to drive the central temperature above a few million degrees, and therefore never succeed in igniting core hydrogen fusion. Discovered in the mid-1990s, these objects initially have surface temperatures of ~3,500K, but cool rapidly and move through spectral types M, L, T and Y. Following their discovery, considerable theoretical attention has focused on the evolution of their intrinsic properties, particularly the details of the atmospheric changes in the evolution from type L through T to Y and beyond. The initial transition marks the emergence of methane as a dominant absorber at near-infrared wavelengths, while ammonia becomes increasingly apparent in the coolest dwarfs identified by the WISE mission. Current models suggest that the L to T transition occurs at ~1400-1200K, while the T to Y transition occurs around 600K. The spectral changes are at least correlated with, and perhaps driven by, the distribution and properties of dust layers ("clouds"). The overall timescales associated with this process remains unclear. Mass is a crucial factor in mapping those changes, but mass is also the most difficult quantity to measure in a reliable fashion. The present proposal tackles this issue through astrometry and photometry of ultracool binary systems, deriving the orbits, and hence dynamical masses, and mapping the spectral energy distributions to probe the temperatures. The targets in this multi-year program include three late-L/T dwarf binaries, spanning the L/T transition.

GO 14793: The First Precise Atmospheric Metallicity Measurement for a Sub-Jovian Exoplanet

An artist's impression of the exoplanet Hap P 11b matched against Neptune for size
The standard model for planet formation hypothesises the initial formation of a relatively dense core, with subsquent accretion of gaseous material to form the gas and ice giants found in our solar system and other stellar systems. Snce the accreted material is dominated by volatiles (mainly hydrogen), that model predicts that smaller planets should have higher metallicity atmospheres. Transiting exoplanets are an invaluable resource for testing this hypothesis since their brief transit across the face of the primary star not only gives a direct measurement of their diameter, but also can provide an opportunity to sample the chemical composition of the atmosphere. Following Kepler, more than 2000 such systems are now known, extending to small terrestrial planets; nonetheless, much of the information gleaned by the explanet community comes from earlier discoveries based on ground-based monitoring. This simply reflects the fact that those surveys targeted bright stars, and therefore give the spectral analysts more photons to work with during transit. One of the most interesting systems is HAT-P-11b, a Neptune-sized planet orbiting a K4 dwarf lying some 37 parsecs from the Sun. Past HST and Spitzer observations rsulted in the detection in water at wavelengths between 1.1 and 1.7 microns in what seems to be a relatively cloud-free atmosphere. The present program aims to build on those observations by probing shorter wavelengths, measuring the metallicity of the atmosphere.

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