This week on HST

HST Programs: January 15 - January 21 2018

Program Number Principal Investigator Program Title
14610 Julianne Dalcanton, University of Washington A Legacy Imaging Survey of M33.
14624 Hector G. Arce, Yale University Taming the Flame: A Near-IR imaging study of the NGC 2024 (Flame Nebula) cluster
14656 Ivana Orlitova, Astronomical Institute, Academy of Sciences of CR How does ionizing radiation escape from galaxies?
14683 Jean-Claude Bouret, CNRS, Laboratoire d'Astrophysique de Marseille Before the Burst: The Properties of Rapidly Rotating, Massive Supergiants
14684 David V. Bowen, Princeton University What is a Galaxy Halo Really Like?
14697 Bradley M Peterson, The Ohio State University A Cepheid Distance to NGC 4051
14712 Raghvendra Sahai, Jet Propulsion Laboratory HST-COS Ultraviolet Spectroscopy of B[e] Supergiant Stars in the Magellanic Clouds
14840 Andrea Bellini, Space Telescope Science Institute Schedule Gap Pilot
15077 Tucker Jones, University of California - Davis Accurate Emission Line Diagnostics at High Redshift
15083 Michael Rodruck, The Pennsylvania State University Star Clusters in Tidal Debris: A UV Survey of Stellar Populations, Galaxy Interactions, and Evolution
15084 J. Michael Shull, University of Colorado at Boulder Hot Photons: Measuring the Ionizing Continuum and EUV Emission Lines of Quasars
15113 Abhijit Saha, National Optical Astronomy Observatory, AURA Extending the DA white dwarf spectrophotometric network to the Southern Hemisphere
15132 Harald Ebeling, University of Hawaii Beyond MACS: A Snapshot Survey of the Most Massive Clusters of Galaxies at z>0.5
15145 Adam Riess, The Johns Hopkins University The Hubble Constant to 1%: Physics beyond LambdaCDM
15146 Adam Riess, The Johns Hopkins University A New Threshold of Precision, 30 micro-arcsecond Parallaxes and Beyond
15153 Dan Watson, University of Rochester The jets and shocks of NGC 1333: a large WFC3 mosaic of [Fe II] and H I line emission
15162 Peter Blanchard, Harvard University Constraining the Late-Time Light Curve Behavior of Three Diverse Superluminous Supernovae
15165 Catherine Espaillat, Boston University Connecting mass accretion and ejection in pre-main sequence stars
15166 Alex V. Filippenko, University of California - Berkeley Continuing a Snapshot Survey of the Sites of Recent, Nearby Supernovae: Cycles 25 & 26
15174 R. O. Parke Loyd, Arizona State University Investigating an SPI and Measuring Baseline FUV Variability in the GJ 436 Hot-Neptune System
15186 David Thilker, The Johns Hopkins University Enabling HST UV Exploration of the Low Surface Brightness Universe: A Pilot Study with the WFC3 X Filter Set
15201 Clemence Fontanive, Royal Observatory Edinburgh Looking for the Coldest Atmospheres: a Search for Planetary Mass Companions around T and Y Brown Dwarfs
15212 Michele Trenti, University of Melbourne The brightest galaxies in the first 700 Myr: Building Hubble's legacy of large area IR imaging for JWST and beyond
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
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
15248 Scott Sander Sheppard, Carnegie Institution of Washington A Satellite Search of a Newly Discovered Dwarf Planet
15278 Rolf A. Jansen, Arizona State University UV-Visible Imaging of the JWST NEP Time-Domain Field: the *best* extragalactic survey field *always* accessible to JWST
15320 Tommaso L. Treu, University of California - Los Angeles Probing the dark universe with quadruply imaged quasars
15330 Daniela Calzetti, University of Massachusetts - Amherst The Emergence of Star Clusters
15333 Ian Crossfield, Massachusetts Institute of Technology The Atmospheric Diversity of Mini-Neptunes in Multi-planet Systems
15344 David Jewitt, University of California - Los Angeles Centaurs and Activity Beyond the Water Sublimation Zone
15411 Miguel Perez-Torres, Instituto de Astrofisica de Andalucia (IAA) VLBA monitoring of the extraordinary changing-look quasar Mrk 1018
15448 Marianne Vestergaard, University of Copenhagen, Niels Bohr Institute Constraining the emergent EUV ionizing emission in the reawakening monster in Mrk 590

Selected highlights

GO 14684: What is a Galaxy Halo Really Like?

The barred spiral, NGC 1097
Galaxy formation, and the overall history of star formation within a galaxy, clearly demands the presence of gas. The detailed evolution therefore depends on how gas is accreted, recycled, circulated through the halo and, perhaps, ejected back into the intergalactic medium. Tracing that evolutionary history is difficult, since gas passes through many different phases, some of which are easier to detect than others. During accretion and, probably, subsequent recycling, the gas is expected to be reside predominantly at high temperatures. The most effective means of detecting such gas is through ultraviolet spectroscopy, where gas within nearby systems can be detected as absorption lines superimposed on the spectra of more distant objects, usually quasars. The present program builds on a Cycle 20 program (GO 12998) that used the Cosmic Origins Spectrograph to observe four QSOs whose sightlines passed through the circumgalactic medium of NGC 1097, a barred spiral with a central AGN. The sysme lies ~12 Mpc from the Milky Way. The present program adds observations of a further four background sources. The COS observations will cover Lyman-alpha, as well as ionised lines of Si II, Si III, Si IV and C III, extending coverage to larger galactic radii and further probing the gas flows in and out of the system.

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 15248: A Satellite Search of a Newly Discovered Dwarf Planet

HST images of the dwarf planet Eris and satellite Dysnomia
The Kuiper Belt consists of icy planetoids that orbit the Sun within a broad band stretching from Neptune's orbit (~30 AU) to distance of ~50 AU from the Sun. Over 500 KBOs are currently known out of a population of perhaps 70,000 objects with diameters exceeding 100 km. Approximately 2% of the known KBOs are binary; indeed, 11 of the 15 largest systems have detected satellites. This is a surprisingly high fraction, given the difficulties involved in forming such systems and the relative ease with which they can be disrupted. It remains unclear whether these systems formed from single KBOs (through collisions or 3-body interactions) as the Kuiper Belt and the Solar System have evolved, or whether they represent the final tail of an initial (much larger) population of primordial binaries. Interestingly, some observations suggest that the largest KBOs may be higher density, implying larger masses and a greater ability to retain satellites, potentially accounting for the higher satellite fraction. The recently discovered 2013 FY27 is the ninth brightest KBO known, suggesting that it may be among the top 10 in size. The present program aims to obtain deep imaging with the WFC3 UVIS channel to determine whether this system has a satellite.

GO 15333: The Atmospheric Diversity of Mini-Neptunes in Multi-planet Systems

Artist's impression of a mini-Neptune or super-Earth
With the discovery of the first exoplanet orbiting a main-sequence star, 51 Pegb, a hot jupiter, it became clear that the Solar System was not a universal template. Since then, the intrinsic diversity has grown. In particular, Kepler revealed a significant number of planets with dimensions intermediate between the terrestrial planets and ice giants in the solar system. These are planets are common, present in 1 in 4 systems, and are described as either super-earths or mini-Neptunes, reflecting our lack of understanding, with no local analogues, of whether these are giant rocks or mini iceballs. The present prorgam aims to probe this issue through observations of four such planets, all members of multi-planet systems; HD 3167c, HD 106315c, HIP 41378b and K2-3b. The present program will use the WFC3/IR G141 grism to map the near-IR spectral energy distribution through several transits, searching for characteristic features due to water and methane, probing the metallicity, C/O ratio and aerosol atmospheric content.

Past weeks:
page by Neill Reid, updated 3/1/2018
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