This week on HST

HST Programs: July 14 - July 20, 2008

Program Number Principal Investigator Program Title Links
11107 Timothy M. Heckman, The Johns Hopkins University Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation in the Early Universe Abstract
11113 Keith S. Noll, Space Telescope Science Institute Binaries in the Kuiper Belt: Probes of Solar System Formation and Evolution Abstract
11122 Bruce Balick, University of Washington Expanding PNe: Distances and Hydro Models Abstract
11130 Luis Ho, Carnegie Institution of Washington AGNs with Intermediate-mass Black Holes: Testing the Black Hole-Bulge Paradigm, Part II Abstract
11151 Gregory J. Herczeg, California Institute of Technology Evaluating the Role of Photoevaporation of Protoplanetary Disk Dispersal Abstract
11156 Kathy Rages, SETI Institute Monitoring Active Atmospheres on Uranus and Neptune Abstract
11158 R. Michael Rich, University of California - Los Angeles HST Imaging of UV emission in Quiescent Early-type Galaxies Abstract
11172 Arlin Crotts, Columbia University in the City of New York Defining Classes of Long Period Variable Stars in M31 Abstract
11196 Aaron S. Evans, State University of New York at Stony Brook An Ultraviolet Survey of Luminous Infrared Galaxies in the Local Universe Abstract
11197 Peter Garnavich, University of Notre Dame Sweeping Away the Dust: Reliable Dark Energy with an Infrared Hubble Diagram Abstract
11202 Leon Koopmans, Kapteyn Astronomical Institute The Structure of Early-type Galaxies: 0.1-100 Effective Radii Abstract
11206 Kai G. Noeske, University of California - Santa Cruz At the cradle of the Milky Way: Formation of the most massive field disk galaxies at z>1 Abstract
11212 Douglas R. Gies, Georgia State University Research Foundation Filling the Period Gap for Massive Binaries Abstract
11219 Alessandro Capetti, Osservatorio Astronomico di Torino Active Galactic Nuclei in nearby galaxies: a new view of the origin of the radio-loud radio-quiet dichotomy? Abstract
11235 Jason A. Surace, California Institute of Technology HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in the Local Universe Abstract
11237 Lutz Wisotzki, Astrophysikalisches Institut Potsdam The origin of the break in the AGN luminosity function Abstract
11545 Ben Davies, Rochester Institute of Technology A NICMOS survey of newly-discovered young massive clusters Abstract
11547 Dimitrios Gouliermis, Max-Planck-Institut fur Astronomie, Heidelberg Characterizing Pre-Main Sequence Populations in Stellar Associations of the Large Magellanic Cloud Abstract
11800 Keith Noll, Space Telescope Science Institute Hubble Heritage imaging of NGC 3324 in the Carina Nebula Abstract

Some selected highlights

GO 11113: Binaries in the Kuiper Belt: Probes of Solar System Formation and Evolution

A composite of HST images of the Kuiper Belt binary, WW31 The Kuiper Belt consists of icy planetoids that orbit the Sun within a broad band stretching from Neptune's orbit (~30 AU) to distance sof ~50 AU from the Sun (see David Jewitt's Kuiper Belt page for details). 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 (including Pluto, one of the largest known KBOs, regardless of whether one considers it a planet or not). 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. This proposal will use WFPC2 imaging of known KBOs to identify new binary systems.

GO 11172: Defining Classes of Long Period Variable Stars in M31

M31, The Andromeda galaxy Most long period variable stars (LPVs) are red giants on the asymptotic giant branch (AGB). These are intermediate mass stars, between ~1.5 and ~7 solar masses, that are powered by hydrogen and helium shell-burning. The interactions between the two energy sources lead to instabilities that can generate substantial pulsations, with periods from ~50 to ~500 days. Mira, or omicron Ceti, is the Galactic prototype for this type of variable, and numerous LPVs have been identified throughout the Milky Way and in the neighbouring Small and Large Magellanic Clouds. The LMC and SMC variables show a clear period-luminosity relation, particularly at near-infrared wavelengths, with longer period stars having higher intrinsic luminosities. This P-L relation, while not as well established for classical cepheids, allows LPVs to contribute to measurements of the extragalactic distance scale. The present program aims to expand LPV surveys to M31, using the NIC1 and NIC2 cameras within NICMOS to obtain follow-up near-infrared imaging of regions of the Andromeda galaxy that have been observed with ACS and WFPC2 in previous cycles. These new observations will both provide detailed colour-magnitude diagrams for the selected areas and allow the identification of LPVs within the Andromeda disk population.

GO 11235: HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in the Local Universe

NICMOS image of the interacting LIRG, NGC 6090 Luminous infrared galaxies (LIRGs) have total luminosities that exceed 1011.4 LSun, with most of the energy emitted at wavelengths longward of 10 microns. Many (perhaps most) of these galaxies are interacting or merging disk galaxies, with the excess infrared luminosity generated by warm dust associated with the extensive star formation regions. Many systems also have an active nucleus, and may be in the process of evolving towards an S0 or elliptical merger remnant. The present program surveys a total of 88 such systems from the IRAS Revised Bright Galaxy Sample, imaging each system with the H-band F160W filter on the NICMOS NIC2 camera. The observations will be used to probe
  • the luminosity and distribution of star formation activity, particularly embedded star clusters;
  • the presence of AGNs and the relationship between star formation and AGN activity;
  • the correlations between near-infrared emission and the mid-IR structures identified from Spitzer IRAC imaging;
  • the presence of coherent structure, bars or bridges, that might funnel gas into the nuclei;
  • and the overall structural properties of the LIRGS as a function of luminosity and environment
Observations of several interacting systems are scheduled for this week.

Past weeks:
page by Neill Reid, updated 18/5/2008