31 research outputs found
Fitting the integrated Spectral Energy Distributions of Galaxies
Fitting the spectral energy distributions (SEDs) of galaxies is an almost
universally used technique that has matured significantly in the last decade.
Model predictions and fitting procedures have improved significantly over this
time, attempting to keep up with the vastly increased volume and quality of
available data. We review here the field of SED fitting, describing the
modelling of ultraviolet to infrared galaxy SEDs, the creation of
multiwavelength data sets, and the methods used to fit model SEDs to observed
galaxy data sets. We touch upon the achievements and challenges in the major
ingredients of SED fitting, with a special emphasis on describing the interplay
between the quality of the available data, the quality of the available models,
and the best fitting technique to use in order to obtain a realistic
measurement as well as realistic uncertainties. We conclude that SED fitting
can be used effectively to derive a range of physical properties of galaxies,
such as redshift, stellar masses, star formation rates, dust masses, and
metallicities, with care taken not to over-interpret the available data. Yet
there still exist many issues such as estimating the age of the oldest stars in
a galaxy, finer details ofdust properties and dust-star geometry, and the
influences of poorly understood, luminous stellar types and phases. The
challenge for the coming years will be to improve both the models and the
observational data sets to resolve these uncertainties. The present review will
be made available on an interactive, moderated web page (sedfitting.org), where
the community can access and change the text. The intention is to expand the
text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics &
Space Scienc
Supernova Interaction with a Circumstellar Medium
The explosion of a core collapse supernova drives a powerful shock front into
the wind from the progenitor star. A layer of shocked circumstellar gas and
ejecta develops that is subject to hydrodynamic instabilities. The hot gas can
be observed directly by its X-ray emission, some of which is absorbed and
re-radiated at lower frequencies by the ejecta and the circumstellar gas.
Synchrotron radiation from relativistic electrons accelerated at the shock
fronts provides information on the mass loss density if free-free absorption
dominates at early times or the size of the emitting region if synchrotron
self-absorption dominates. Analysis of the interaction leads to information on
the density and structure of the ejecta and the circumstellar medium, and the
abundances in these media. The emphasis here is on the physical processes
related to the interaction.Comment: 22 pages, 7 figures, to appear as a Chapter in "Supernovae and
Gamma-Ray Bursts," edited by K. W. Weiler (Springer-Verlag
Characteristics of rotenone-insensitive oxidation of matrix-NADH by broad bean mitochondria
PHYSICAL CHARACTERISTICS OF a-AMYLASE HYDROLYSATES FROM UNMODIFIED AND CHEMICALLY-MODIFIED WAXY MAIZE STARCHES
Effects of allelopathic compounds of corn pollen on respiration and cell division of watermelon
Site testing Dome A, Antarctica
Recent data have shown that Dome C, on the Antarctic plateau, is an exceptional site for astronomy, with atmospheric conditions superior to those at any existing mid-latitude site. Dome C, however, may not be the best site on the Antarctic plateau for every kind of astronomy. The highest point of the plateau is Dome A, some 800 m higher than Dome C. It should experience colder atmospheric temperatures, lower wind speeds, and a turbulent boundary layer that is confined closer to the ground. The Dome A site was first visited in January 2005 via an overland traverse, conducted by the Polar Research Institute of China. The PRIC plans to return to the site to establish a permanently manned station within the next decade. The University of New South Wales, in collaboration with a number of international institutions, is currently developing a remote automated site testing observatory for deployment to Dome A in the 2007/8 austral summer as part of the International Polar Year. This self-powered observatory will be equipped with a suite of site testing instruments measuring turbulence, optical and infrared sky background, and sub-millimetre transparency. We present here a discussion of the objectives of the site testing campaign and the planned configuration of the observatory