This week on HST


HST Programs: February 26 - March 4, 2007

Program Number Principal Investigator Program Title Links
10610 George Benedict, University of Texas at Austin Astrometric Masses of Extrasolar Planets and Brown Dwarfs Abstract
10792 Matthias Dietrich, The Ohio State University Research Foundation Quasars at Redshift z=6 and Early Star Formation History Abstract
10798 Leon Koopmans, Kapteyn Astronomical Institute Dark Halos and Substructure from Arcs & Einstein Rings Abstract
10802 Adam Riess, Space Telescope Science Institute SHOES-Supernovae, HO, for the Equation of State of Dark energy Abstract
10808 Pieter van Dokkum, Yale University Morphologies of spectroscopically-confirmed red and dead galaxies at z~2.5 Abstract
10811 Colin Borys, University of Toronto Morphology of a most spectactular Spitzer selected galaxy Abstract
10836 S. Stanford, University of California - Davis The Red Sequence at 1.3 < z < 1.4 in Galaxy Clusters Abstract
10862 John Clarke, Boston University Comprehensive Auroral Imaging of Jupiter and Saturn during the International Heliophysical Year Abstract
10871 John Spencer Southwest Research Institute Observations of the Galilean Satellites in Support of the New Horizons Flyby Abstract
10890 Arjun Dey, NOAO Morphologies of the Most Extreme High-Redshift Mid-IR-Luminous Galaxies Abstract
10906 Sylvain Veilleux, University of Maryland The Fundamental Plane of Massive Gas-Rich Mergers: II. The QUEST QSO Abstract
10912 Howard Bond, Space Telescope Science Institute Trigonometric Calibration of the Distance Scale for Classical Novae Abstract
10918 Wendy Freedman, Carnegie Institution of Washington educing Systematic Errors on the Hubble Constant: Metallicity Calibration of the Cepheid PL Relation Abstract
10931 Edmund Nelan, Space Telescope Science Institute Dynamical Masses and Radii of Four White Dwarf Stars Abstract
10989 George Benedict, University of Texas at Austin Astrometric Masses of Extrasolar Planets and Brown Dwarfs Abstract
11080 Daniela Calzetti, University of Massachusetts Exploring the Scaling Laws of Star Formation Abstract
11082 Christopher Conselice, University of Nottingham NICMOS Imaging of GOODS: Probing the Evolution of the Earliest Massive Galaxies, Galaxies Beyond Reionization, and the High Redshift Obscured Universe Abstract
11083 Pat Cote, Herzberg Institute The Structure, Formation and Evolution of Galactic Cores and Nuclei Abstract
11084 Dan Zucker, Institute of Astronomy, Cambridge Probing the Least Luminous Galaxies in the Local Universe Abstract
11096 The Hubble Heritage Team, STScI Hubble Heritage imaging of Jupiter during the New Horizons encounter Abstract

Some selected highlights

GO 10792: Quasars at Redshift z=6 and Early Star Formation History

SDSS 1030+0524, one of the high redshift QSOs targeted in this program One of the major achievements of the Sloan Digital Sky Survey has been the detection of numerous high redshift quasars. These high luminosity objects serve as cosmic lamp-posts when it comes to probing star formation at such early epochs (lookback times exceeding 10 Gyrs): quasars are powered by accretion onto black holes, which are likely to form in high-mass (proto-)galaxies; those galaxies, in turn, are likely to be in high density environments (i.e. proto-clusters); thus, detailed investigations of the properties of high-redshift QSOs is likely to provide a snapshot of galaxy structure at thse early epochs. The present proposal concentrates on z>6 QSOs, using the NICMO grisms to obtain low resolution near-IR spectra that will allow measurement of the relative abundance of Fe and Mg in those objects. Magnesium is an alpha element, generated predominantly in Type II SN; Fe comes predominantly from Type I SN, which require 0.5-1 Gyrs to reach fruition; hence, this ratio provides an estimate of the time that has elapsed since the first outburst of star formation in these systems.

GO 10802: SHOES-Supernovae, HO, for the Equation of State of Dark energy

WFPC2 image of NGC 4639, one of the spirals targeted in this program The cosmic distance scale and dark energy are two key issues in modern astrophysics, and HST has played a vital role in probing both. On the one hand, HST has been involved in cosmic distance measurements since its inception, largely through the H0 Key Project, which used WFPC2 to identify and photometer Cepheids in 31 spiral galaxies at distances from 60 to 400 Mpc. On the other, HST is the prime instrument for investigating cosmic acceleration by searching for and following Type Ia supernovae at moderate and high redshift. These two cosmological parameters are directly related, and recent years have seen renewed interest in improving the accuracy of H0 with the realization that such measurements, when coupled with the improved constraints from the Cosmic Microwave Background, provide important constraints on cosmic acceleration and the nature of Dark Energy. The present HST program was designed to combine observations that tackle both questions. The recent failure of the ACS Wide-Field Camera means that it will no longer be possible to search for new high-redshift supernovae. However, NICMOS is satill available to observe known Cepheids in several Key Project spirals that have hosted Type Ia supernovae. The near-infrared data will provide more accurate distance estimates for those galaxies, tying together the Cepheid and SN Ia distance scales.

GO 11083: The Structure, Formation and Evolution of Galactic Cores and Nuclei

A wide-field view of the Virgo cluster The Virgo cluster, lying at a distance of ~20 MPc, is the nearest large galaxy cluster. The cluster embraces more than 2,000 galaxies, with masses ranging from ~3 x1012 MSun for the central giant elliptical, M87, to ~109 MSun dwarf systems, predominantly ellipticals but witha smattering of irregulars. In Cycle 11, the same proposal used the Advanced Camera for Surveys to observe more than 100 elliptical and S0 galaxies in Virgo, obtaining deep images in the SDSS g (green) and z (far-red) passbands. These observations show a systematic variation with luminosity in the surfacve brightness profile. Giant ellipticals have a relatively flat brightness profile in the central regions, while dwarfs tends to have compact nuclei. The aim of the current proposal is to use ultraviolet (WFPC2/F225W) and near-infrared (NIC1/F160W) images of the central regions to probe star formation and the star formation history on scales of 0.1-1.0 arcsecond (10-100 parsecs).

GO 11096: Hubble Heritage imaging of Jupiter during the New Horizons encounter

The Voyager 1 observation of the Loki eruption on Io The New Horizons probe is not scheduled to reach Pluto until July 2015. On the way, however, it passes by Jupiter, and will use the Jovian gravitational field to provide the slingshot energy to accelerate its trip to the outer regions of the Solar System. New Horizons will make its closest approach to Jupiter on February 28th, when it will pass by at a distance of only 2.3 million km. The New Horizons instruments will be used to observe Jupiter itself, the Jovian magnetosphere, the larger satellites and the Jovian rings. HST will be working in support of those observations, using WFPC2 and the ACS Solar Blind Channel to monitor auroral activity and the atmospheric structure on Jupiter, and surveying the Galilean satellites, particularly volcanic Io.

Past weeks:
page by Neill Reid, updated 28/1/2007