This week on HST

HST Programs: June 4 - June 10, 2007

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 those early epochs. The present proposal concentrates on z>6 QSOs, using the NICMOS 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 10877: A Snapshot Survey of the Sites of Recent, Nearby Supernovae

A recent supernova in M100

Supernovae mark the (spectacular) evolutionary endpoint for a subset of stellar systems. Standard models predict that they originate from massive stars and (probably) close binaries with a compact (WD, neutron star) component, but there are still some questions remaining over whether we fully understand the range of possible progenitors. The last decade has seen the development of a number of large-scale programs, usually using moderate-sized telescopes, that are dedicated to monitoring (relatively nearby galaxies, searching for new supernovae. This program obtains follow-up images of recent supernovae, concentrating on systems within 20 Mpc of the Milky Way. The observations are taken well after maximum, with the aim of using the high spatial resolution of WFPC2 to identify the fading remnant and perhaps determine its origin.

GO 11082: NICMOS Imaging of GOODS: Probing the Evolution of the Earliest Massive Galaxies, Galaxies Beyond Reionization, and the High Redshift Observational Universe

ACS images of a section of the GOODS fields

The Great Observatories Origins Deep Survey, is a large-scale program that is designed to probe galaxy formation and evolution at redshifts from z~1 to z~6. GOODS covers two ~150 sq. arcminute fields, one centred on the Hubble Deep Field and the second on the Chandra Deep Field South, and combines deep oppical/far-red imaging (F435W, F606W, F775W and F850LP filters) using ACS on HST with deep IRAC (3.6 to 8 micron) and MIPS (25 micron) imaging with Spitzer. Chandra data are also available for the bulkd of the field. The present program aims to supplement those data with near-infrared H-band (F160W) imaging with NICMOS, coupled (eventually) with parallel ultraviolet observations using the ACS/SBC.

GO 11310: Jupiter's North Temperate Belt Disturbance

Jupiter on April 23, 2007 (taken by (see Christopher Go ); the image is inverted. The light brown spot with darker centre, lying on the northern edge of the North Temperate Belt, was a precursor to the development of new structure in the NTB.

Jupiter on April 29, 2007 (also (see Christopher Go ); the NTB shows more extensive disturbances and the dark spot is Io's shadow.

Jupiter's atmosphere is characterised by series of banded latitudinal features, designated alternately as belts (dark features) or zones. These are circulation cells, produced by the high Coriolis force generated by Jupiter's dense atmosphere and rapid rotation rate (the diurnal period of 9.9 hours corresponds to a speed of 12.5 km/sec at the equator). The different colours correspond to different depths within the Jovian atmosphere, with the lighter-coloured zones generally corresponding to ammonia clouds in the uppermost layers. In general, the belt/zone structure is fairly stable with time, although smaller-scale disturbances are not infrequent (such as the recent appearance of a ). During March, a disturbance developed in the North Temperate Belt, with the appearance of several bright spots that developed darker trailing features. This type of behaviour has been seen several times in the past, most recently in 1990, and often culminates in the formation of a new dark zone that circumnavigates the entire NTB. This proposal will use multicolour imaging with WFPC2 to sample Jupiter's atmosphere at different depths, and hence investigate the wind profile in the disturbed region.