This week on HST

HST Programs: December 18 - December 24 2017

Program Number Principal Investigator Program Title
14608 Nadia L Zakamska, The Johns Hopkins University Host galaxies of high-redshift quasars with extreme outflows
14635 Yuri I. Izotov, Ukrainian National Academy of Sciences, MAO Lyman continuum leaking in luminous compact star-forming galaxies
14640 John Sebastian Pineda, University of Colorado at Boulder Investigating the FUV Emission of Young M dwarfs with FUMES: the Far Ultraviolet M-dwarf Evolution Survey
14697 Bradley M Peterson, The Ohio State University A Cepheid Distance to NGC 4051
14716 Francesca Annibali, INAF, Osservatorio Astronomico di Bologna DDO 68: A flea with smaller fleas that on him prey
14747 Brant Robertson, University of California - Santa Cruz Lyman Continuum Escape Survey (LACES): Detecting Ionizing Radiation from z~3 LAEs with Powerful Optical Lines
14767 David Kent Sing, University of Exeter The Panchromatic Comparative Exoplanetary Treasury Program
14772 Bart P. Wakker, University of Wisconsin - Madison Observing gas in Cosmic Web filaments to constrain simulations of cosmic structure formation
14775 Roeland P. van der Marel, Space Telescope Science Institute The Proper Motion Field along the Magellanic Bridge: a New Probe of the LMC-SMC interaction
14785 Sjoert van Velzen, New York University Enhanced rates of tidal disruptions in E+A galaxies: resolving the central dynamics of post-starburst galactic nuclei with HST observations
14840 Andrea Bellini, Space Telescope Science Institute Schedule Gap Pilot
14921 Monika Lendl, Space Research Institute, Austrian Academy of Sciences Atmospheric escape from a mini-Neptune
15073 Boris T. Gaensicke, The University of Warwick Extreme evolved solar systems (EESS)
15107 Benne Willem Holwerda, University of Louisville Research Foundation, Inc. The Cluster Population of UGC 2885
15123 Aaron J. Barth, University of California - Irvine Probing the accretion flow and emission-line regions of M81, the nearest broad-lined low-luminosity AGN
15132 Harald Ebeling, University of Hawaii Beyond MACS: A Snapshot Survey of the Most Massive Clusters of Galaxies at z>0.5
15133 Peter Erwin, Max-Planck-Institut fur extraterrestrische Physik Solving the Mystery of Galaxy Bulges and Bulge Substructure
15140 Ragnhild Lunnan, Stockholm University Resolving the Connection Between Superluminous Supernovae and Star Formation in Dwarf Galaxies
15145 Adam Riess, The Johns Hopkins University The Hubble Constant to 1%: Physics beyond LambdaCDM
15174 R. O. Parke Loyd, Arizona State University Investigating an SPI and Measuring Baseline FUV Variability in the GJ 436 Hot-Neptune System
15201 Clemence Fontanive, Royal Observatory Edinburgh Looking for the Coldest Atmospheres: a Search for Planetary Mass Companions around T and Y Brown Dwarfs
15222 Iair Arcavi, University of California - Santa Barbara What Type of Star Made the One-of-a-kind Supernova iPTF14hls?
15238 Adam L. Kraus, University of Texas at Austin The IMF to Planetary Masses Across the Milky Way
15242 Lucia Marchetti, Open University SNAPshot observations of the largest sample of lensed candidates in the Equatorial and Southern Sky identified with Herschel
15257 Patrick Hartigan, Rice University Proper Motions, Shear, Mass-Loss Rates and C-Shocks in the HH 7-11 Jet
15265 John Blakeslee, NRC Herzberg Institute of Astrophysics MASSIVE+: The Growth Histories of MASSIVE Survey Galaxies from their Globular Cluster Colors
15295 Marie Ygouf, California Institute of Technology Revealing the birth environment of circumbinary exoplanets with STIS BAR5
15333 Ian Crossfield, Massachusetts Institute of Technology The Atmospheric Diversity of Mini-Neptunes in Multi-planet Systems
15336 Annette Ferguson, University of Edinburgh, Institute for Astronomy The Globular Cluster Systems of Local Group Dwarf Galaxies
15344 David Jewitt, University of California - Los Angeles Centaurs and Activity Beyond the Water Sublimation Zone
15378 Matthew Bayliss, Massachusetts Institute of Technology The Chandra Strong Lens Sample: Revealing Baryonic Physics In Strong Lensing Selected Clusters
15423 David Jewitt, University of California - Los Angeles Characterization of Distant Comet C/2017 K2

Selected highlights

GO 14697: A Cepheid Distance to NGC 4051

The spiral galaxy, NGC 4051
Cepheid variable stars have been the prime extragalactic distance indicator since Henrietta Leavitt's discovery of the period-luminosity relation described by Cepheids in the Small Magellanic Cloud. It was Hubble's identification of Cepheids in NGC 6822 that finally established that at least some nebulae were island universes. Cepheids and the extragalactic distance scale figure largely in HST's history, notably through the Hubble Constant Program, one of the initial Key Projects. HST has since observed Cepheids in more than 30 galaxies. The present program aims to extend observations to the Seyfert galaxy, NGC 4051, a near-face-on spiral lying at a distance of 9-18 Mpc from the Milky Way. NGC 4051 is one of the best studied Seyferts, having been the target of extensive reverberatikon mapping campaign designed to probe the detailed velocity structure of the ionised gas near the central black hole. This program will use multi-epoch imaging with the WFC3-UVIS and WFC3-IR cameras to identify and monitor Cepheid variables in the system, using the photometric measurements to determine the distance and better constrain the central gas accretion rate. These observations will be coupled with ground-based spatially-resolved spectroscopy of the nuclear regions to determine the mass of the central black hole.

GO 14775: The Proper Motion Field along the Magellanic Bridge: a New Probe of the LMC-SMC interaction

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. A recent Cycle 21 program focused on the SMC, targeting 30 newly identified background QSos for WFC3 observations over a two-year period. The present program follows up on a Cycle 22 program, providign second epoch observations of several fields along the Magellanic bridge, a complex of gas and stars that connects the two clouds. The derived motions will test the hypothesis that the clouds are undergoing their first interaction with teh Milky Way.

GO 15201: Looking for the Coldest Atmospheres: a Search for Planetary Mass Companions around T and Y Brown Dwarfs

NICMOS images of the ultracool L/T binary, 2MASS J22521073-1730134
Ultracool dwarfs are defined as having spectral types later than M7, and therefore include the L, T and Y dwarfs discovered over the past two decades. They encompass the lowest mass stars (masses < ~0.1 MSub) and sub-stellar mass brown dwarfs, with surface temperatures ranging from ~2500K (~M7) through ~700K (late-type T dwarfs) to the room-temperature (~250-300K) Y dwarfs uncovered by WISE. Following their discovery over a decade ago, considerable theoretical attention has focused on potential formation mechanisms for these very low-mass objects. In particular, there have been suggestions that these are "stars interrupted" - cores that were ejected from the natal cocoon of the parent molecular cloud before they could accrete sufficient material to reach the hydrogen-burning mass limit. One means of testing this hypothesis is by studying the binary properties, since dynamical ejection is likely to disrupt wider, weakly bound systems. So far, the observations show that utlracool binaries are indeed preferentially found with small separations (<15 AU) - although not quite as small as theory predicts. Interestingly, almost all of the known systems also have components with near-equal mass. The current program is using the WFC3-IR camera to survey the coolest known systems, with temperatures below 800K,

Past weeks:
page by Neill Reid, updated 31/8/2017
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