This week on HST

HST Programs: February 19 - February 25 2018

Program Number Principal Investigator Program Title
14610 Julianne Dalcanton, University of Washington A Legacy Imaging Survey of M33.
14662 Luigi R. Bedin, Osservatorio Astronomico di Padova The end of the White Dwarf Cooling Sequences of Omega Centauri
14840 Andrea Bellini, Space Telescope Science Institute Schedule Gap Pilot
15067 Kris Davidson, University of Minnesota - Twin Cities Eta Carinae's Change of State: The End Game
15082 Andrew Robinson, Rochester Institute of Technology Monsters on the move: Confirming gravitational wave recoiling supermassive black hole candidates
15100 Jeff Cooke, Swinburne University of Technology Mapping the escaping ionizing flux of Lyman continuum galaxies
15101 Haakon Dahle, University of Oslo A high-definition study of the brightest lensed galaxy in the universe
15128 Alexander Brown, University of Colorado at Boulder Inner Disk Structure and Transport Mechanisms in the Transitional Disk around T Cha
15133 Peter Erwin, Max-Planck-Institut fur extraterrestrische Physik Solving the Mystery of Galaxy Bulges and Bulge Substructure
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
15162 Peter Blanchard, Harvard University Constraining the Late-Time Light Curve Behavior of Three Diverse Superluminous Supernovae
15174 R. O. Parke Loyd, Arizona State University Investigating an SPI and Measuring Baseline FUV Variability in the GJ 436 Hot-Neptune System
15176 Maxwell Andrew Millar-Blanchaer, Jet Propulsion Laboratory Resolving the late planet formation stages around young M-stars
15177 Anna Nierenberg, University of California - Irvine Testing CDM with the WFC3 Grism
15196 David V. Bowen, Princeton University How Do Inflows and Outflows from Galaxies Create Their Inner Circumgalactic Medium?
15208 Raghvendra Sahai, Jet Propulsion Laboratory Star-Formation in Free-Floating Evaporating Gaseous Globules
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
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
15242 Lucia Marchetti, Open University SNAPshot observations of the largest sample of lensed candidates in the Equatorial and Southern Sky identified with Herschel
15303 Chris D'Andrea, University of Pennsylvania Revealing the Environmental Dependence in Superluminous Supernovae Diversity
15310 Christopher Michael Johns-Krull, Rice University A Survey for Molecular Hydrogen Emission Around Stars Forming Terrestrial Planets
15314 Jamie R. Lomax, University of Washington High Fidelity Imaging of a Red Supergiant's Circumstellar Material
15344 David Jewitt, University of California - Los Angeles Centaurs and Activity Beyond the Water Sublimation Zone
15376 Diana Worrall, University of Bristol The X-ray-radio morphology anomaly in a high-redshift quasar jet
15406 Karen J. Meech, University of Hawaii Cause and characteristics of the major outburst of comet C/2017 O1 (ASASSN)
15424 William B. Sparks, Space Telescope Science Institute An intensive ultraviolet imaging campaign for Europa's plumes
15425 Katherine de Kleer, California Institute of Technology Eclipse Observations of Europa's Water Plumes
15438 Jennifer L Sokoloski, Columbia University in the City of New York Gamma-ray Quiet Novae: What Sets the Gamma-Ray Luminosity of Novae?

Selected highlights

GO 15082: Monsters on the move: Confirming gravitational wave recoiling supermassive black hole candidates

An artist's impression of the environs of a supermassive black hole
Supermassive black holes are generally believed to reside in the centres of most galaxies. Reaching masses in excess of a million solar masses, they grow by accretion from the local environment. Observations of merging galaxies sometimes show evidence for the presence of two black holes, and in some cases the expectation is that those black holes might become bound in a binary system - and if the binding were sufficiently tight, they might even spiral inwards to coalesce, producing substantial signal in gravitational waves. The single SMBH resulting from these mergers receives a recoil kick of the order of several thousand km/sec, leading to oscillations about the centre of mass of the galaxy. These oscillations are weakly damped, with the consequence that the SMBH can be significantly (10-100 pc.) off-centre at the present day. Based on previous observations, the present team has identified 18 candidate AGNs where the active nuclei appear to be displaced from the photometric centroid of the galaxy. The current program aims to image six of those systems using the F110W and F160W filters on the WFC3-IR channel; the near-infarred images will map the underlying stellar distibution and confirm whether the AGN are off-centre.

GO 15101: A high-definition study of the brightest lensed galaxy in the universe

ESO NTT/EFOCS imaging of the lensed galaxy asociated with PSZ1 G311.65-18.48
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 structure of the higher-redshift lenses systems. The present program focuses on one such system, discovered in follow-up ground-based imaging of PSZ1 G311.65-18.48, a Sunyaez-Zelodovich cluster canadidate from the Planck survey. The lensed system is a star-forming galaxy at moderately distant redshift, z~2.37. The present program aims to use the Advanced Camera for Surveys (ACS) and Wide-Field Camera 3 (WFC3) to obtain high-resolution multi-band imaghing and grism spectoscopy, probing the detailed characteristics of the system.

GO 15208: Star-Formation in Free-Floating Evaporating Gaseous Globules

The putative evaporating protostar, the frEGG IRAS 20324
Star formation occurs within giant molecular clouds as the gaseous material collapses in the higher density regions, accreting onto central cores. As those cores grow in mass, the central temperature rises, leading to a trend towards hydostatic equilibrium, the formation of a protostellar structrue, and, eventually, nuclear burning. In most cases, this evolution occurs in highly obscured regions, but massive star formation will disrupt the surroundign gaseous material, formign an H II region and revealing protostars in a range of evolutionary states. Recent observatons have led to the detection of so-called Free-floating Evaporating Gaseous Globules (frEGGS), protostars within HII regions where the ionising radiation from massive stars is stripping the gas content to form spectacular tadpole-like structures. The geneal supposition is that a protostar lies within the head of this structure. The present program aims to test this hypothesis through multiband imaging (H-alpha, R and I band) of 24 such structures with the Advanced Camera for Surveys. ACS will provide high angular resolution data that can tease out the detailed underlying physical phenomena.

GO 15425: Eclipse Observations of Europa's Water Plumes

The HST imaging of a potential water plume around Europa's south pole superimposed on an image of the satellite
Europa is the smallest, and the most intriguing, of the four Galilean satellites of Jupiter. With a diameter of 3139 km, Europa is almost twice the size of Earth's moon and significantly larger than Mercury. In 1957, Gerard Kuiper commented that both infrared spectroscopy and the optical colours and albedo suggested that Jovian satellite II (Europa) is covered "by H2O snow". Images taken by the Voyager space probes in the late 1970s (see left) reveal a smooth surface, with only a handful of craters larger than a few kilometres. These features are consistent with a relatively young, icy surface. Subsequent detailed investigations by the Galileo satellite strongly suggest that a substantial body of liquid water, heated by tidal friction, underlies a 5 to 50 km thick icy crust. The presence of this subterranean (subglacial?) ocean clearly makes Europa one of the two most interesting astrobiology targets in the Solar System. Over the last few years analyses of observations taken by both the Space Telescope Imaging Spectrograph (STIS) and the Advanced Camera for Surveys Solar Blind Channel (ACS/SBC) on Hubble have revealed the presence of extended cloud semission near the polar regions, strongly suggesting that Europa's oceans may be vaporising into space. These clearly provide an opportunity for a fly-by mission to sample the sub-surface ocean. The emission is sporadic, however. The present program is one of several that aim to characterise the frequency and prominence of these events, in this case using STIS to search for emission from atomic species in these putative clouds. The observations are time to cover Europa during eclipse to enhence the potential for detections.

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