This week on HST


HST Programs: October 2 - October 8, 2017

Program Number Principal Investigator Program Title
14216 Robert P. Kirshner, Harvard University RAISIN2: Tracers of cosmic expansion with SN IA in the IR
14597 Jay Farihi, University College London An Ultraviolet Spectral Legacy of Polluted White Dwarfs
14611 Or Graur, Harvard University Going gently into the night: constraining Type Ia supernova nucleosynthesis using late-time photometry
14677 Tim Schrabback, Universitat Bonn, Argelander Institute for Astronomy Probing the most distant high-mass galaxy clusters from SPT with HST weak lensing observations
14680 Jonathan Charles Tan, The University of Virginia Kinematics of a Massive Star Cluster in Formation
14689 Dimitrios Gouliermis, Zentrum fur Astronomie - Universitat Heidelberg MYSST: Mapping Young Stars in Space and Time - The HII Complex N44 in the LMC
14710 Antonino Paolo Milone, Australian National University Multiple Stellar Populations in Young Magellanic Cloud Clusters
14747 Brant Robertson, University of California - Santa Cruz Lyman Continuum Escape Survey (LACES): Detecting Ionizing Radiation from z~3 LAEs with Powerful Optical Lines
14749 Mischa Schirmer, Gemini Observatory, Southern Operations Low redshift Lyman-alpha blobs
14756 Amy Simon, NASA Goddard Space Flight Center Hubble 2020: Outer Planet Atmospheres Legacy (OPAL) Program
14760 Zheng Cai, University of California - Santa Cruz Imaging a Massive Galaxy Overdensity at z=2.3: The Morphology-Density Relation at High Redshift
14767 David Kent Sing, University of Exeter The Panchromatic Comparative Exoplanetary Treasury Program
14781 Chris S. Kochanek, The Ohio State University Ultraviolet Spectroscopic Monitoring of an ASAS-SN Tidal Disruption Event
14784 Evgenya L. Shkolnik, Arizona State University HAZMAT: Habitable Zones and M dwarf Activity across Time
14796 Denija Crnojevic, Texas Tech University An extremely asymmetric dwarf satellite distribution around M101
14840 Andrea Bellini, Space Telescope Science Institute Schedule Gap Pilot
15081 Andrew Robinson, Rochester Institute of Technology Revealing the circum-nuclear torus: HST imaging of active galaxies observed during a Spitzer reverberation mapping campaign
15119 Jason J. Wang, University of California - Berkeley Probing the young circumplanetary environment of Beta Pic b during transit egress
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
15279 Sean Johnson, Princeton University Unveiling Quasar Fueling through a Public Snapshot Survey of Quasar Host Environments
15307 Michael D. Gladders, University of Chicago Building the SPT-HST Legacy: Imaging Massive Clusters to z=1.5
15320 Tommaso L. Treu, University of California - Los Angeles Probing the dark universe with quadruply imaged quasars
15364 Andrea Bellini, Space Telescope Science Institute Extended F814W Schedule Gap Pilot

Selected highlights

GO 14611: Going gently into the night: constraining Type Ia supernova nucleosynthesis using late-time photometry


A recent supernova in M100
Supernovae mark the (spectacular) evolutionary endpoint for a subset of stellar systems. Standard models predict that they originate from massive stars and (probably) close binaries with a compact (WD, neutron star) component, although there are still some questions remaining over whether we fully understand the range of possible progenitors. During the eruption, supernovae return a wide range of nucleosynthetic products to the interstellar medium through their ejecta. The remnants fade over time; theory predicts that the primary residual heat source for Type Ia supernovae is radioactive decay from cobalt to iron. The present program aims to test these theoretical predictons through late-time observations of two recent Type Ia supernovae, SN 2015F in NGC 2442 and ASASSN-14lp in NGC 4666 (from December 2014). Wide Field Camera 3 is being used to monitor the photometric behaviour at optical wavelengths (essentially B, V, R and I) to match against the theory.

GO 14680: Kinematics of a Massive Star Cluster


IR imaging and ALMA mapping of the G286 star formation region
Understanding the detailed physics involved in forming stars is still one of the main challenges for modern astronomy. G286.21+0.17 (BYF73) is an extremely young massive protocluster in Carina, lying at a distance of ~2.5 kpc. from the Sun. Unlike ~10 Myr-old clusters, such as NGC 3603 or the Arches cluster, the system is still dominated by dense molecular gas. Previous optical and radio/sub-millimetre observations found clear evdience for large-scale gravitational infall within the dense gas.The present program aim to use near-infrared observations with WFC3 to probe the detailed kinematics. These observations build on observations taken with the same instrumental configuration in autumn 2014 as part of a Cycle 22 prorgam. The second epoch dta will enable proper motions measurements for the many sub-clusters of stars identifie in the first epoch data.

GO 14767: The Panchromatic Comparative Exoplanetary Treasury Program


Artist's impression of the GJ 1214 system
The first exoplanet, 51 Peg b, was discovered through radial velocity measurements in 1995. 51 Pegb was followed by a trickle, and then a flood of other discoveries, as astronomers realised that there were other solar systems radically different from our own, where "hot jupiters" led to short-period, high-amplitude velocity variations. Then, in 1999, came the inevitable discovery that one of those hot jupiters. HD 209458b, was in an orbit aligned with our line of sight to the star, resulting in transits. Since that date, the number of known transiting exoplanet systems has grown to more than 100 from ground-based observations, most detected through wide-field photometric surveys, while the high-sensitivity data provided by Kepler has added a further 1000+ confirmed systems and ~2000 additional candidates. Transiting systems not only provide an accurate measure of the planetary radius (at least relative to the parent star), they also provide us with an opportunity to probe the atmospheric composition through spectroscopy during the transit. Hubble has made significant inroads in this area, while Spitzer has contributed measurements of planetary emissivity through observations during and after eclipse. The James Webb Space Telescope has the capability to revolutionise our knowledge in this field through highly sensitiive observations at near and mid-infra red wavelengths. The present program aims to lay the foundation for those programs by using Hubble to compile multiwavelength (UV to near-IR) spectroscopic observations of 20 exoplanets. The targets are all gas giants, ranging from super-jovian masses to neptunian masses. The observations will be obtained with the Space Telescope Imaging Spectrograph and the near-infrared grisms on Wide Field Camera 3.

GO 15145: The Hubble Constant to 1%: Physics beyond LambdaCDM


NGC 7541 (upper left), one of the spiral galaxies targeted in this program
The Hubble constant remains a key parameter in understanding cosmology and the evolution of the Universe. Recent investigations have identified what is becoming a significant tension between the values derived from traditional measurements of the astronomical distance scale and those derived from the analyses of the Planck microwave background dataset. Refining measurements of H0 therefore still represents a vital means of probing the nature of dark energy. The present program aims to tackle this question by laying a firmer foundation to the SNe Ia distance scale, building on past HST observations programs. The WFC3 UVIS camera will be used to identify Cepheids and long-period variables (Miras) in ten relatively nearby galaxies that have hosted Type Ia SNe. These observatons will utilise the wide-band F350LP filter, using the larger amplitudes that these vaiables show at visual wavelengths to ease identification of the targets. In contrast, follow-up observations with the WFC3-IR camera and the F160W filter will take advantage of the lower-amplitude variations at near-IR wavelengths to establish reliable mean magnitudes, and hence define the observed period-luminosity relations for both Cepheids and miras. Those data, in turn, will better establish the distances to these galaxies and tie down the zeropoint of the supernova distance scale. The ultime aim is to reduce the level of systematics in determinations of H0 to the 1% level, setting signficantly stronger constraints on dark energy.

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