1,525 research outputs found
VLA Observations of the "Eye of the Tornado"- the High Velocity \HII Region G357.63-0.06
The unusual supernova remnant candidate G357.7-0.1 and the compact source
G357.63-0.06 have been observed with the Very Large Array at 1.4 and 8.3 GHz.
The H92 line (8.3 GHz) was detected from the compact source with a
surprising velocity of about -210 km/s indicating that this source is an \HII
region, is most likely located at the Galactic center, and is unrelated to the
SNR. The \HI absorption line (1.4 GHz) data toward these sources supports this
picture and suggests that G357.7-0.1 lies farther away than the Galactic
center.Comment: Latex, 14 pages including 4 figures. Accepted to A
The Molonglo Galactic Plane Survey: I. Overview and Images
The first epoch Molonglo Galactic Plane Survey (MGPS1) is a radio continuum
survey made using the Molonglo Observatory Synthesis Telescope (MOST) at 843
MHz with a resolution of 43" X 43" cosec |delta|. The region surveyed is 245
deg < l < 355 deg, |b| < 1.5 deg. The thirteen 9 deg X 3 deg mosaic images
presented here are the superposition of over 450 complete synthesis
observations, each taking 12 h and covering 70' X 70' cosec |delta|. The
root-mean-square sensitivity over much of the mosaiced survey is 1-2 mJy/beam
(1 sigma), and the positional accuracy is approximately 1" X 1" cosec |delta|
for sources brighter than 20 mJy. The dynamic range is no better than 250:1,
and this also constrains the sensitivity in some parts of the images. The
survey area of 330 sq deg contains well over 12,000 unresolved or barely
resolved objects, almost all of which are extra-galactic sources lying in the
Zone of Avoidance. In addition a significant fraction of this area is covered
by extended, diffuse emission associated with thermal complexes, discrete H II
regions, supernova remnants, and other structures in the Galactic interstellar
medium.Comment: Paper with 3 figures and 1 table + Table 2 + 7 jpg grayscales for Fig
4. Astrophysical Journal Supplement (in press) see also
http://www.astrop.physics.usyd.edu.au/MGP
Microjansky radio sources in DC0107-46 (Abell 2877)
The cluster DC0107-46 (Abell 2877) lies within the Phoenix Deep Survey, made
at 1.4 GHz with the Australia Telescope Compact Array. Of 89 known optical
cluster members, 70 lie within the radio survey area. Of these 70 galaxies, 15
(21%) are detected, with luminosities as faint as 10^20 W/Hz. Spectroscopic
observations are available for 14/15 of the radio-detected cluster galaxies.
Six galaxies show only absorption features and are typical low-luminosity AGN
radio sources. One galaxy hosts a Seyfert 2 nucleus, two are star-forming
galaxies, and the remaining five may be star-forming galaxies, AGNs, or both.Comment: 14 pages, 3 figures, Accepted by ApJS (v128n2p JUN 2000 issue
Supramolecular Complexation of Carbon Nanostructures by Crown Ethers
Since their discovery, crown ethers as well as the most recent carbon nanostructures, namely fullerenes, carbon nanotubes, and graphene, have received a lot of attention from the chemical community. Merging these singular chemical structures by noncovalent forces has provided a large number of unprecedented supramolecular assemblies with new geometric and electronic properties whose more representative examples are presented in this Synopsis organized according to the different nature of the carbon nanostructures
A high-resolution radio survey of the Vela supernova remnant
This paper presents a high-resolution radio continuum (843 MHz) survey of the
Vela supernova remnant. The contrast between the structures in the central
pulsar-powered nebula of the remnant and the synchrotron radiation shell allows
the remnant to be identified morphologically as a member of the composite
class. The data are the first of a composite remnant at spatial scales
comparable with those available for the Cygnus Loop and the Crab Nebula, and
make possible a comparison of radio, optical and soft X-ray emission from the
resolved shell filaments. The survey, made with the Molonglo Observatory
Synthesis Telescope, covers an area of 50 square degrees at a resolution of
43'' x 60'', while imaging structures on scales up to 30'.Comment: 18 pages, 7 jpg figures (version with ps figures at
http://astro.berkeley.edu/~dbock/papers/); AJ, in pres
SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. I. Science goals, survey design and instrumentation
The Molonglo Observatory Synthesis Telescope, operating at 843 MHz with a 5
square degree field of view, is carrying out a radio imaging survey of the sky
south of declination -30 deg. This survey (the Sydney University Molonglo Sky
Survey, or SUMSS) produces images with a resolution of 43" x 43" cosec(Dec.)
and an rms noise level of about 1 mJy/beam. SUMSS is therefore similar in
sensitivity and resolution to the northern NRAO VLA Sky Survey (NVSS; Condon et
al. 1998). The survey is progressing at a rate of about 1000 square degrees per
year, yielding individual and statistical data for many thousands of weak radio
sources. This paper describes the main characteristics of the survey, and
presents sample images from the first year of observation.Comment: 27 pages, 12 figures (figures 2, 8, 10 in jpg format); AJ, in pres
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