| Program Number | Principal Investigator | Program Title |
|---|---|---|
| 13643 | Gaspard Duchene, University of California - Berkeley | Imaging the tenuous dusty atmosphere of edge-on protoplanetary disks |
| 13650 | Kevin France, University of Colorado at Boulder | The MUSCLES Treasury Survey: Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems |
| 13667 | Marc W. Buie, Southwest Research Institute | Observations of the Pluto System During the New Horizons Encounter Epoch |
| 13671 | Harald Ebeling, University of Hawaii | Beyond MACS: A Snapshot Survey of the Most Massive Clusters of Galaxies at z>0.5 |
| 13677 | Saul Perlmutter, University of California - Berkeley | See Change: Testing time-varying dark energy with z>1 supernovae and their massive cluster hosts |
| 13690 | Tanio Diaz-Santos, Universidad Diego Portales | Tracking the Obscured Star Formation Along the Complete Evolutionary Merger Sequence of LIRGs |
| 13691 | Wendy L. Freedman, University of Chicago | CHP-II: The Carnegie Hubble Program to Measure Ho to 3% Using Population II |
| 13693 | Amanda R. Hendrix, Planetary Science Institute | The Ultraviolet Spectrum of Ceres |
| 13695 | Benne W. Holwerda, Sterrewacht Leiden | STarlight Absorption Reduction through a Survey of Multiple Occulting Galaxies (STARSMOG) |
| 13708 | Nicole Reindl, Eberhard Karls Universitat, Tubingen | Following the rapid evolution of the central star of the Stingray Nebula in real time |
| 13721 | Robert A. Benjamin, University of Wisconsin - Whitewater | The Windy Milky Way Galaxy |
| 13760 | Derck L. Massa, Space Science Institute | Filling the gap --near UV, optical and near IR extinction |
| 13767 | Michele Trenti, University of Melbourne | Bright Galaxies at Hubble's Detection Frontier: The redshift z~9-10 BoRG pure-parallel survey |
| 13771 | Daniel J. Lennon, ESA-European Space Astronomy Centre | PROPER MOTIONS OF ISOLATED MASSIVE STARS NEAR THE GALACTIC CENTER |
| 13774 | Sara Ellison, University of Victoria | Feeding and feeback: The impact of AGN on the circumgalactic medium. |
| 13776 | Michael D. Gregg, University of California - Davis | Completing The Next Generation Spectral Library |
| 13785 | Naveen A. Reddy, University of California - Riverside | Stellar Populations and Ionization States of Lyman Alpha Emitters During the Epoch of Peak Star Formation |
| 13786 | Glenn Schneider, University of Arizona | Decoding Debris System Substructures: Imprints of Planets/Planetesimals and Signatures of Extrinsic Influences on Material in Ring-Like Disks |
| 13821 | Andrew C. Fabian, University of Cambridge | H-alpha Filaments and Feedback in NGC4696 at the centre of the Centaurus cluster |
| 13841 | Alexandre Gallenne, Universidad de Concepcion | Accurate masses and distances of the binary Cepheids S Mus and SU Cyg |
| 13842 | Frederick Hamann, University of Florida | Testing the Youth and Transition Object Status of FeLoBAL Quasars |
| 13846 | Todd Tripp, University of Massachusetts - Amherst | The COS Absorption Survey of Baryon Harbors (CASBaH): Probing the Circumgalactic Media of Galaxies from z = 0 to z = 1.5 |
| 13847 | Kailash C. Sahu, Space Telescope Science Institute | Determining the Mass of Proxima Centauri through Astrometric Microlensing |
| 13849 | Pierre Kervella, Observatoire de Paris | The parallax and mass of the binary classical Cepheid V1334 Cyg |
| 14050 | Laura Kreidberg, University of Chicago | Exploring the Frontiers of Exoplanet Atmosphere Dynamics with NASA's Great Observatories |
| 14206 | Adam Riess, The Johns Hopkins University | A New Threshold of Precision, 30 micro-arcsecond Parallaxes and Beyond |
| 14348 | Yi Yang, Texas A & M University | Polarimetry of ASASSN-15lh as a probe of explosion physics of the most luminous supernova ever discovered |
GO 13643: Imaging the tenuous dusty atmosphere of edge-on protoplanetary disks
The binary system HK Tau; in the case of component HK Tau B, the disk is viewed almost edge on |
Planet formation occurs in circumstellar disks around young stars. Most of the gaseous content of those disks dissipates in less than 10 million years, leaving dusty debris disks that are detectable through reflect light at near-infrared and, to a lesser extent, optical wavelengths. The disk structure is affected by massive bodies (i.e. planets and asteroids), which, through dynamical interactions and resonances, can produce rings and asymmetries. Over the past decade, HST and Spitzer have provided complementary information on this topic, with Spitzer measuring thermal radiation from circumstellar dust and HST providing high-resolution mapping of debris disks in reflected light. Past HST observations of a number of edge-on systems have shown evidence for extended scattered light above and below the disk, suggesting the presence of dust grains in a tenuous "atmosphere" beyond the disk mid-plane. The present program aims to follow up on that discovery by using Wide-Field Camera 3 to obtain blue (F475W) and far-red (F814W) images of six disks to obtain deep imaging that will probe the density structure. |
GO 13667: Observations of the Pluto System during the New Horizons Encounter
The first New Horizon image Pluto and Charon, from a distance of ~200 million km |
Pluto, one of the largest members of the Kuiper Belt and, until recently, the outermost planet in the solar system, is the primary target of NASA's New Horizons Mission and has been the subject of a range of supporting HST programs over the past few years. Those observing programs have added four moons to the Pluto system. James Christy originally identified the largest moon, Charon, in 1978 from photographic plates Charon has a diameter of ~1200 km, or almost half that of Pluto itself. In 2005, Hubble added two small moons, christened Nix and Hydra, approximately 5,000 times fainter than Pluto itself, implying diameters as small as ~30-50 km if the surface composition is similar. More recent observations, in support of New Horizons mission, aimed to use WFC3 to search for faint rings due to dust particles that might jeopardise the space craft and require a course correction. While no rings were detected unequivocally, two small satellite, christened "P4" and "P5", have been discovered. Both are significantly fainter than Nix and Hydra, and may well be as small as 10-13 km in size. There is also some evidence that might point to the presence of a debris ring within Charon's orbit. Most recently, Hubble carried out an extensive imaging survey to identify KBOs lying beyond pluto that might seve as targets for an extended new Horizons mission. Two such candidates were identified, and Hubble will be conducting follow up observations to further constrain their orbits. The present observations are in direct support of the primary New Horizons mission. WFC3 is being used to provide a comprehensive set of direct imaging and grism observations that provide reference data to give the broad context for interpreting New Horizons data compiled during the highly successful July 14th system fly-by. |
GO 13841: Accurate masses and distances of the binary Cepheids S Mus and SU Cyg
The radial velocity curve (left) and pulsational velocity curve (middle) of the primary component of the binary Cepheid, V1334 Cyg (Gallene et al, A&A, 552, A21) |
SU Cygni and S Muscae are short-period (P = 3.8 days, 9.66 days) classical Cepheid variables lying at a distance of a few hundred parsecs from the Sun. Both are known binary systems, with SU Cyg harbouring a ~4 solar mass, B6 companion and S Muscae matched with a 3-5 solar mass, B3-B5 companion. At optical wavelengths, the combined flux is dominated by the cooler Cepheid in these systems, but hot companion is detectable at ultraviolet wavelengths. The present program aims to use STIS to obtain ultraviolet spectra that will enable measurement of the radial velocity curve for the hot companions in these systems. Those observations will be combined with existing ground-based measurements of the Cepheid radial velocities, therefore determing velocity curves for both stars. Combining those data with high-precision astrometric measurements from ground-based interferometry will allow a direct measurement of mass and distance for both systems. |
GO 13847: Determining the Mass of Proxima Centauri through Astrometric Microlensing
 An AAO image centred on the nearby red dwarf, Proxima Centauri |
Gravitational lensing is a consequence of general relativity. Its effects were originally quantified by Einstein himself in the mid-1920s. In the 1930s, Fritz Zwicky suggested that galaxies could serve as lenses, but lower mass objects can also also lens background sources. Bohdan Paczynski pointed out in the mid-1980s that this offered a means of detecting dark, compact objects that might contribute to the dark-matter halo. Paczcynski's suggestion prompted the inception of several large-scale lensing surveys, notably MACHO, OGLE, EROS and DUO. Those wide-field imaging surveys have target high density starfields towards the Magellanic Clouds and the Galactic Bulge, and have succeeded in identifying numerous lensing events. The duration of each event depends on several factors, including the tangential motion of the lens and its mass. Long-term events are generally associated with a massive lens, but duration alone is not sufficient to characterise the lens since a slow-moving source with low mass can mimic a fast-moving high-mass lens. However, microlensing not only leads to flux amplification, but also to small astrometric motions, caused by the appearance and disappearance of features in the lensed light. Those motions serve as a mass discriminant - higher mass lenses produce larger amplitude motions. The present program aims to capitalise on this fact by measuring the positional deflection of a background stars induced by the close passage of Proxima Centauri, the late-type, low-luminosity M dwarf tertiary companion of Alpha Centauri and the nearest star to the Sun. As a nearby star, Proxima has a well-defined proper motion and parallax, and it will pass close (within 1.5 arcsecnds) to two 18th magnitude stars in May 2015 and June 2015, respectively. The expected signals during the encounters (i.e. the deflection of the background stars) are expected to be approximately 0.5 millarcseconds, and therefore within HST's astrometric capabilities. |