This week on HST


HST Programs: February 12 - February 18 2018

Program Number Principal Investigator Program Title
14610 Julianne Dalcanton, University of Washington A Legacy Imaging Survey of M33.
14619 Jessica Spake, University of Exeter Characterising the atmosphere of a uniquely low-density, sub-Saturn mass planet
14633 Kevin France, University of Colorado at Boulder A SNAP UV Spectroscopic Study of Star-Planet Interactions
14656 Ivana Orlitova, Astronomical Institute, Academy of Sciences of CR How does ionizing radiation escape from galaxies?
14682 Bjorn Benneke, Universite de Montreal A Search for Methane, Ammonia, and Water on Two Habitable Zone Super-Earths
14697 Bradley M Peterson, The Ohio State University A Cepheid Distance to NGC 4051
15113 Abhijit Saha, National Optical Astronomy Observatory, AURA Extending the DA white dwarf spectrophotometric network to the Southern Hemisphere
15133 Peter Erwin, Max-Planck-Institut fur extraterrestrische Physik Solving the Mystery of Galaxy Bulges and Bulge Substructure
15144 Keith S. Noll, NASA Goddard Space Flight Center Deep Search for Satellites Around the Lucy Mission Targets
15145 Adam Riess, The Johns Hopkins University The Hubble Constant to 1%: Physics beyond LambdaCDM
15166 Alex V. Filippenko, University of California - Berkeley Continuing a Snapshot Survey of the Sites of Recent, Nearby Supernovae: Cycles 25 & 26
15175 Eileen T Meyer, University of Maryland Baltimore County An Infrared Imaging Test of the IC/CMB Model for the Unusual Spectrum of AP Librae
15201 Clemence Fontanive, Royal Observatory Edinburgh Looking for the Coldest Atmospheres: a Search for Planetary Mass Companions around T and Y Brown Dwarfs
15203 Cecile Gry, Laboratoire d'Astrophysique de Marseille First exploration of a single thermal interface between the two dominant phases of the interstellar medium
15213 David E. Trilling, Northern Arizona University A Pure Parallel survey of the colors of small trans-Neptunian objects to constrain the collisional history of the Outer Solar System
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
15223 Matthew Auger, University of Cambridge The Brightest Galaxy-Scale Lens
15241 Kirsten L. Larson, California Institute of Technology Clumpy Star Formation in Local LIRGS
15242 Lucia Marchetti, Open University SNAPshot observations of the largest sample of lensed candidates in the Equatorial and Southern Sky identified with Herschel
15245 Christopher P. O'Dea, University of Manitoba The Co-Evolution of Star Formation and Powerful Radio Activity in Galaxies During Radio-Mode Feedback
15310 Christopher Michael Johns-Krull, Rice University A Survey for Molecular Hydrogen Emission Around Stars Forming Terrestrial Planets
15344 David Jewitt, University of California - Los Angeles Centaurs and Activity Beyond the Water Sublimation Zone
15364 Andrea Bellini, Space Telescope Science Institute Extended F814W Schedule Gap Pilot
15406 Karen J. Meech, University of Hawaii Cause and characteristics of the major outburst of comet C/2017 O1 (ASASSN)
15425 Katherine de Kleer, California Institute of Technology Eclipse Observations of Europa's Water Plumes
15429 Martin A. Cordiner, NASA Goddard Space Flight Center Is C60+ present in the diffuse interstellar medium?
15430 Baptiste Lavie, Observatoire de Geneve Atmopsheric Escape from the Closest Super-Earth at High Spectral Resolution
15448 Marianne Vestergaard, University of Copenhagen, Niels Bohr Institute Constraining the emergent EUV ionizing emission in the reawakening monster in Mrk 590
15449 Max Mutchler, Space Telescope Science Institute Optical and infrared imaging of the Lagoon Nebula (M8)

Selected highlights

GO 14610: A Legacy Imaging Survey of M33


M33, the Triangulum Galaxy (Subaru imaging)
Messier 33, or the Triangulum galaxy, is the smallest of the three spiral galaaxies in the Local Group. Lying at a distance of ~800 kpc from the Milky Way, the system may be a satellite of the Andromeda spiral, and certainly appears to have experienced past interactions. With a mass less than half that of the Milky Way, the galaxy has a small, distinct bulge, no bar and extensive star formation regions forming spiral structure. The proximity to the Milky Way means that Hubble can resolve individual stars, albeit limited to relatively high luminosities. The present program aims to build on that capability by mapping aproximately one-third of the system. Wide Field Camnera 3 and the Advanced Camera for Surveys will be used in parallel to image 54 fields, obtaining multi-band data from the near-UV (F275W filter) through the U, B and I bands (F336W, F475W, F814W) to the near-infarred (F110W and F160W). Those data will enable investigations of the initial mass function for luminous stars; trace the detailed star formation and recent history as a function of location within the galaxy; map the dust distribution; and allow for the detection of star clusters. This dataset will complement the extensive survey of the Andromeda spiral conducted via the PHAT survey.

GO 15144: Deep Search for Satellites Around the Lucy Mission Targets


Artist's impresson of the Patroclus/Menoetius system
The Solar System includes a number of regions occupied by numerous small solid bodies, notably the main asteroid belt, between the orbits of Mars and Jupiter, and the Edgeworth-Kuiper Belt, beyond the orbit of Neptune. More than 96,000 bodies have been catalogued in the former region, including the larger (few hundred km diameter) minor planets like Ceres, Pallas, Juno and Vesta. The main belt asteroids fall into three main categories: carbonaeous (C-type), silicate (S-type) and metal-rich (M-type). A subset of these asteroids have been captured by Jupiter into orbits that lead or trail Jupiter itself by ~ 60 degrees. These are the Trojan asteroids. The first, Achilles, was detected in 1908 by Max Wolf; there are now close to 4,000 known members, with the largest around 150 km in size; there may be as many as 600,000 larger than 1 km in diameter. NASA's Lucy Mission, scheduled for launch in October 2021, is dedicated to the first in situ survey of those objects. The aim is to target close fly-bys of one main belt asteroid and six Trojans. The present HST program aims to pave the way for the final mission by using deep imaging with Hubble's Wide-Field Camera 3 to search for low-mass satellite companions of the targets, which include Eurybates, Orus, Leucus, Polymele and the Patroclus/Menoetius binary system.

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,

GO 15242: SNAPshot observations of the largest sample of lensed candidates in the Equatorial and Southern Sky identified with Herschel


An ALMA/HST composite image of the lensed galaxy, SDP 81
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. Until recently, the most common background sources that were being detected and investigates were quasars. Galaxy-galaxy lenses, however, offer a distinct advantage, since the background source is extended, and therefore imposes a stronger constraints on the mass distribution of the lensing galaxy than a point-source QSO. HST has carried out a number of programs following up candidate lenses identified from the Sloan Digital Sky Survey and based on sub-mm observation by the Herschel satellite. The present program aims to build on the latter sample by using Hubble Snapshot imaging with the F110W filter in the WFC3-IR camera to verify the nature of up to 200 lensing candidates from the major herschel extragalactic surveys.

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