3,598 research outputs found
JHK Imaging and Photometry of Low z QSOs and Radio Galaxy
We describe J,H,K deep imaging of 90 arcmin fields around 4 QSOs and one
Radio galaxy at redshifts in the range 0.06 to 0.30, and show their images,
luminosity profiles, and NIR 2-colour diagrams of objects. We find that the QSO
hosts are all resolved, and compare them with previous CCD images. The host
galaxy colours are consistent with old and young stellar populations at the QSO
redshift. The colours of nearby galaxies suggest that all the AGN live in
groups of generally smaller companion galaxies, mostly with evolved populations
at the same redshift. The two radio-loud objects live in richer cluster
environments than the others. Gissel population models indicate reddening in
the galaxies, star-forming regions, and possibly a systematic H-K offset. The
QSO luminosity profiles are complex and reveal some of their tidal disturbance
and star-formation history.Comment: 22 pages of text (latex), 2 tables )latex), and 15 figures
(postscript). Accepted for publication in AJ, February 1997. Also available
at http://www.dao.nrc.ca/DAO/SCIENCE/science.htm
Amplifier provides dual outputs from a single source with complete isolation
Amplifier provides two amplified outputs from a single input signal with complete transformer isolation. It uses modulation techniques to obtain the separated output
Geometrically nonlinear Cosserat elasticity in the plane: applications to chirality
Modelling two-dimensional chiral materials is a challenging problem in
continuum mechanics because three-dimensional theories reduced to isotropic
two-dimensional problems become non-chiral. Various approaches have been
suggested to overcome this problem. We propose a new approach to this problem
by formulating an intrinsically two-dimensional model which does not require
references to a higher dimensional one. We are able to model planar chiral
materials starting from a geometrically non-linear Cosserat type elasticity
theory. Our results are in agreement with previously derived equations of
motion but can contain additional terms due to our non-linear approach. Plane
wave solutions are briefly discussed within this model.Comment: 22 pages, 1 figure; v2 updated versio
A Supernova Factory in the Merger System Arp 299
We have imaged the nearby galaxy merger Arp 299 at arcsecond and
milliarcsecond resolution, using both the Very Large Array and the Very Long
Baseline Array. The large-scale radio emission from the merger contains 5
bright, compact radio sources embedded in diffuse emission, with diameters less
than 200 pc. Supernova rates of 0.1 to 1 per year are required to produce the
VLA-detected radio emission in these sources. Two of the compact VLA radio
sources, designated Source A and Source D, also have been detected and imaged
at milliarcsecond scales. Source A, which is associated with the nucleus of one
of the merging galaxies, contains five milliarcsecond-scale sources, each with
a radio power between 100 and 1000 times that of the Galactic supernova remnant
Cassiopeia A. Four of these have flat or inverted spectra and appear to be
young supernovae. Three of the VLBI-scale sources are located within 10 pc
(projected) of one another, and two are separated by less than 3 pc, indicating
that they all may be within the same super starcluster or complex of such
clusters. The brightest VLBI-scale source, A0, has an extremely inverted
pectrum, with alpha larger than +2 at gigahertz frequencies. It seems to be the
youngest supernova, which has not yet broken out of its circumstellar shell.
The milliarcsecond radio sources within Source A appear to constitute a
upernova factory, confirming the presence of an extreme starburst that peaked
at least a few million years ago.Comment: Accepted for the Astrophysical Journal, 22 pages, 10 figure
Scientific Objectives for UV/Visible Astrophysics Investigations: A Summary of Responses by the Community (2012)
Following several recommendations presented by the Astrophysics Decadal
Survey 2010 centered around the need to define "a future ultraviolet-optical
space capability," on 2012 May 25, NASA issued a Request for Information (RFI)
seeking persuasive ultraviolet (UV) and visible wavelength astrophysics science
investigations. The goal was to develop a cohesive and compelling set of
science objectives that motivate and support the development of the next
generation of ultraviolet/visible space astrophysics missions. Responses were
due on 10 August 2012 when 34 submissions were received addressing a number of
potential science drivers. A UV/visible Mission RFI Workshop was held on 2012
September 20 where each of these submissions was summarized and discussed in
the context of each other. We present a scientific analysis of these
submissions and presentations and the pursuant measurement capability needs,
which could influence ultraviolet/visible technology development plans for the
rest of this decade. We also describe the process and requirements leading to
the inception of this community RFI, subsequent workshop and the expected
evolution of these ideas and concepts for the remainder of this decade.Comment: 22 pages, 1 figure, 3 table
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