This week on HST


HST Programs: October 9 - October 15 2017

Program Number Principal Investigator Program Title
14216 Robert P. Kirshner, Harvard University RAISIN2: Tracers of cosmic expansion with SN IA in the IR
14603 C Simon Jeffery, Armagh Observatory Ulraviolet fluxes and dynamical structure in the pulsating atmosphere of helium star V652 Her
14608 Nadia L Zakamska, The Johns Hopkins University Host galaxies of high-redshift quasars with extreme outflows
14636 Igor Dmitrievich Karachentsev, Russian Academy of Sciences, Special Astrophysical Obs. TRGB Distances to the Edge Between the Local Sheet and Virgo Infall: Last of the Low Hanging Fruit
14639 Thomas J. Maccarone, Texas Tech University Finding AM CVn stars in 47 Tuc
14689 Dimitrios Gouliermis, Zentrum fur Astronomie - Universitat Heidelberg MYSST: Mapping Young Stars in Space and Time - The HII Complex N44 in the LMC
14735 Flavien Kiefer, CNRS, Institut d'Astrophysique de Paris Observation of OH in Beta Pictoris exocomets
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
14791 Martin Barstow, University of Leicester Assessing the dependency of the fine structure constant on gravity using hot DA white dwarfs
14800 Robert A. Fesen, Dartmouth College Mapping Calcium Rich Ejecta in Two Type Ia Supernovae
14840 Andrea Bellini, Space Telescope Science Institute Schedule Gap Pilot
14847 Margarita Karovska, Smithsonian Institution Astrophysical Observatory MULTIWAVELENGTH STUDY OF POWERFUL NEW JET ACTIVITY IN THE SYMBIOTIC SYSTEM R AQR
15077 Tucker Jones, University of California - Davis Accurate Emission Line Diagnostics at High Redshift
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
15207 Alex Harrison Parker, Southwest Research Institute The Moons of Kuiper Belt Dwarf Planets Makemake and 2007 OR10
15215 Vardha N. Bennert, Cal Poly Corporation, Sponsored Programs Department A Local Baseline of the Black Hole Mass - Host Galaxy Scaling Relations for Active Galaxies
15304 Julien de Wit, Massachusetts Institute of Technology Collecting the Puzzle Pieces: Completing HST's UV+NIR Survey of the TRAPPIST-1 System ahead of JWST
15307 Michael D. Gladders, University of Chicago Building the SPT-HST Legacy: Imaging Massive Clusters to z=1.5
15318 Kailash C. Sahu, Space Telescope Science Institute Detecting Isolated Black Holes through Astrometric Microlensing

Selected highlights

GO 14636 :TRGB Distances to the Edge Between the Local Sheet and Virgo Infall: Last of the Low Hanging Fruit


The galaxies within the Local Group
The Milky Way Galaxy is a member of a relatively sparse set of galaxies known as the Local Group. Fifty-four members are currently catalogued within ~1.5 Mpc., with the overwhelming majority being dwarf systems. The Milky Way and M31 are the two dominant members, with M33 the only other spiral system. Moving beyond the Local Group, we encounter five further galaxy groups within ~3 Mpc: the M81 group, the Canes I group, the Maffei group, the Sculptor group and the NGC 5128 group ( see this link ). Beyond them lies the Virgo supercluster. HST is well suited to mapping the distance distribution of the inner groups: the high sensitivity of the Advanced Camera for Surveys and Wide-Field Camera 3 combined with the unparalleled angular resolution enables resolution of the most luminous stars; constructing the colour-magnitude provides access to a number of distance indicators, including the tip of the first red giant branch (RGB). Red giants have completed the core hydrogen-burning main-sequence stage of evolution and have moved to burning hydrogen in an inner shell. The maximum luminosity in this phase, and hence the location of the tip of the RGB, is set when the core reaches a sufficiently high temperature to ignite helium burning, the so-called helium flash. At that point, hydrogen shell-burning is extinguished, the star contracts and moves onto the horizontal branch. The present program focuses on 20 galaxies lying ion the so-called "Local Sheet" in the foreground of the Virgo cluster. These systems have expected distances of 6-8 Mpc., lying at the extremes of the current capabilities of the TPRG method with Hubble.

GO 14735: Observation of OH in Beta Pictoris exocomets


The beta Pictoris disk
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. The relatively nearby A-type star Beta Pictoris has one of the most prominent, and best studied, circumstellar disks. Age estimates range from 8 to 20 million years, and the disk shows evidence for significant sub-structure that has been attributed to planetary companions. The disk itself is likely replenished by material from planetismals and exocomets, generated either collisionally or by evaporation. Past observations with the Cosmic Origins Spectrograph have resulted in the detection of several gaseous species, including C II, N I, O I and ionised Si. The present program aims to extend observations to search for OH absorption at 3085 Angstroms, indicative of the presence of water.

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 15307: Building the SPT-HST Legacy: Imaging massive clusters to z=1.5


The South Pole Telescope at the Amundsen-Scott South Pole Station
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. Galaxy clusters can be identified at moderate redshifts by searching for signatures of the Sunyaev-Zeldovich effect: high energy electrons in the hot intercluster medium interact with radiation from the cosmic microwave background to distort the microwave spectrum. The South Pole Telescope is a 10-metre microwave/millimetre telescope located at Amundsen-Scott South Pole Station on the Antarctiva high plateau, close to the geographic South Pole. That telescope has been used to search for galaxy clusters. As intense mass concentrations, these systems are 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 SNAP program targets 293 clusters at redshifts 0.2 < z < 1.5 drawn from the SPT catalogue. Wide Field Camera 3 will be used to obtain near-IR imaging with the F110W filter (J band) together with broad-band (F200LP filter) imaging with the UVIS camera. The resultant data will provide information on galaxy morphology and the star forming characteristics of these systems, probing the evolution of the most massive galaxies, as well as providing insight on the cluster lensing characteristics.

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