This week on HST

HST Programs: September 4 - September 10 2017

Program Number Principal Investigator Program Title
14119 Luciana C. Bianchi, The Johns Hopkins University Understanding Stellar Evolution of Intermediate-Mass Stars from a New Sample of SiriusB-Like Binaries
14141 Guy Worthey, Washington State University NGSL Extension 1. Hot Stars and Evolved Stars
14163 Mickael Rigault, Humboldt Universitat zu Berlin Honing Type Ia Supernovae as Distance Indicators, Exploiting Environmental Bias for H0 and w.
14181 S Thomas Megeath, University of Toledo A Snapshot WFC3 IR Survey of Spitzer/Hershel-Identified Protostars in Nearby Molecular Clouds
14212 Karl Stapelfeldt, Jet Propulsion Laboratory A Snapshot Imaging Survey of Spitzer-selected Young Stellar Objects in Nearby Star Formation Regions*.t23
14216 Robert P. Kirshner, Harvard University RAISIN2: Tracers of cosmic expansion with SN IA in the IR
14483 Andrew James Levan, The University of Warwick XMM and HST Target of Opportunity Observations of Tidal Disruption Events
14606 Brooke Devlin Simmons, University of California - San Diego Secular Black Hole Growth and Feedback in Merger-Free Galaxies
14679 Daniel P. Stark, University of Arizona Extremely Metal Poor Galaxies with HST/COS: Completing the Groundwork for JWST
14704 Charlie Conroy, Harvard University A Year in the Whirlpool
14731 Graham M. Harper, University of Colorado at Boulder Si I and C I emission from zeta Aurigae (K4 Ib + B5 V): New Generation Diagnostics of Chromospheric Structure
14734 Nitya Kallivayalil, The University of Virginia Milky Way Cosmology: Laying the Foundation for Full 6-D Dynamical Mapping of the Nearby Universe
14744 Daeseong Park, Korea Astronomy and Space Science Institute (KASI) A Definitive UV-Optical Template for Iron Emission in Active Galactic Nuclei
14760 Zheng Cai, University of California - Santa Cruz Imaging a Massive Galaxy Overdensity at z=2.3: The Morphology-Density Relation at High Redshift
14762 Justyn Robert Maund, University of Sheffield A UV census of the sites of core-collapse supernovae
14765 Ian U. Roederer, University of Michigan The Unexplored Domains of the s-Process
14767 David Kent Sing, University of Exeter The Panchromatic Comparative Exoplanetary Treasury Program
14771 Nial Rahil Tanvir, University of Leicester r-process kilonovae, short-duration GRBs, and EM counterparts to gravitational wave sources
14776 Trent J. Dupuy, Gemini Observatory, Northern Operations Mapping the Substellar Mass-Luminosity Relation Down to the L/T Transition
14779 Melissa Lynn Graham, University of Washington A NUV Imaging Survey for Circumstellar Material in Type Ia Supernovae
14783 Kailash C. Sahu, Space Telescope Science Institute Detecting Isolated Black Holes through Astrometric Microlensing
14784 Evgenya L. Shkolnik, Arizona State University HAZMAT: Habitable Zones and M dwarf Activity across Time
14806 Goeran Oestlin, Stockholm University SAFE: Star clusters, lyman Alpha and Feedback in Eso338-04
14840 Andrea Bellini, Space Telescope Science Institute Schedule Gap Pilot
14846 Aaron Romanowsky, San Jose State University Ultra-diffuse Galaxies in Clusters and the Field: Masses and Stellar Populations
14850 Eleonora Troja, University of Maryland Identify the signature of neutron star mergers through rapid Chandra/Hubble observations of a short GRB
14912 Boris T. Gaensicke, The University of Warwick High-precision asteroseismology of the accreting white dwarf in GW Lib through simultaneous HST and K2 observations
14924 Anil C. Seth, University of Utah Increasing Diversity in Galaxies with Black Hole Mass Measurements
14931 Lotfi Ben Jaffel, CNRS, Institut d'Astrophysique de Paris Energy balance in Saturn's upper atmosphere: Joint Lyman-alpha airglow observations with HST and Cassini
15282 Simon J. Lilly, Eidgenossiche Technische Hochschule (ETH) Transport of magnetic fields into the circumgalactic medium
15320 Tommaso L. Treu, University of California - Los Angeles Probing the dark universe with quadruply imaged quasars
15346 Mansi Kasliwal, California Institute of Technology Verifying a candidate counterpart to gravitational waves
15349 Andrew James Levan, The University of Warwick From the longest GRBs to the brightest supernovae

Selected highlights

GO 14181: A Snapshot WFC3 IR Survey of Spitzer/Hershel-Identified Protostars in Nearby Molecular Clouds

An image of the Orion Nebula superimposed on the 13CO map of Orion A (from this link ).
Giant molecular cloud complexes serve as nurseries for star formation. Deeply embedded in dust and gas, young stars are generally extremely difficult to detect at optical wavelengths. Consequently, these complexes have been subject to extensive scrutiny at near- and mid-infrared wavelengths, initially through ground-based observing campaigns and more recently by the Spitzer and Herschel space missions. Those observations have resulted in the identification of numerous embedded sources, young stellar objects (YSOs) that are still accreting from the surrounding molecular gas .he present proposal aims to follow up on those discoveries by obtaining WFC3-IR SNAPs of candidate protostars in several molecular cloud complexes. These observations will provide an excellent complement to Spitzer and Herschel since, while HST cannot offer either the same areal coverage or sensitivity at mid-infrared wavelegths, the imaging has a resolution close to 0.1 arcsecond, an order of magnitude higher than the Spitzer images. The observations are therefore capable of detecting very faint companions, with luminosities consistent with sub-stellar masses, as well as identifying jets and outflows associated with the star formation process. The present program is using the F160W filter to obtain H-band images and determine the true nature of these objects.

GO 14783: Detecting Isolated Black Holes through Astrometric Microlensing

A rather spectacular version of black hole lensing. 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. Duration alone is not sufficient to identify a lens as a black hole - a source with very low tangential motion relative to the Sun can produce the same effect. 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 expected astrometric signal from a black hole lens is > 1.4 millarcseconds, just measureable with HST. This program has capitalised on this fact by searching for lensing by black holes in the Galactic field. The present observations target candidate long-duration lensing events in the Galactic Bulge.

GO 15320: Probing the dark universe with quadruply imaged quasars

The quadruple-imaged quasar RX1131-1231
Gravitational lensing is a consequence the theory of general relativity. Its importance as an astrophysical tool first became apparent with the realisation (in 1979) that the quasar pair Q0957+561 actually comprised two lensed images of the same background quasar. In the succeeding years, lensing has been used primarily to probe the mass distribution of galaxy clusters, using theoretical models to analyse the arcs and arclets that are produced by strong lensing of background galaxies, and the large-scale mass distribution, through analysis of weak lensing effects on galaxy morphologies. Gravitational lensing can also be used to investigate the mass distribution of individual galaxies, while accurate measurements of the time lag in photometric variations (due to differences in the light pathlength) can constrain the value of the Hubble constant. Quadruply lensed quasars offer particularly powerful tools in this regard, but they are rare - as might be expected given the tight constraints on the alignment with the foreground galaxy. The present prorgam aims to almost double the known sample through imaging 13 candidastes with the Advanced Cameras for Surveys.

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