NGC 3576 and NGC 3603: Two Luminous Southern H [CSC]ii[/CSC] Regions Observed at High Resolution with the Australia Telescope Compact Array

1999 ◽  
Vol 117 (6) ◽  
pp. 2902-2918 ◽  
Author(s):  
C. G. De Pree ◽  
Melissa C. Nysewander ◽  
W. M. Goss
Keyword(s):  
High Resolution ◽  
Compact Array

scholarly journals Detection of new sources of 4765-MHz OH masing

2002 ◽  
Vol 206 ◽  
pp. 112-115
Author(s):  
Richard G. Dodson ◽  
Simon P. Ellingsen
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Ground State ◽  
Theoretical Models ◽  
Maser Emission ◽  
Circular Polarisation ◽  
Peak Flux ◽  
Star Formation Regions ◽  
Compact Array

We have used the Australia Telescope Compact Array (ATCA) to make a sensitive search for maser emission from the 4765-MHz transition of OH towards a sample of 55 star formation regions. Maser emission with peak flux densities in excess of 100 mJy were detected in 14 sites, with 10 of these being new discoveries. Unlike the ground-state OH transitions the 4765-MHz transition is not predicted to be circularly polarised and none of the masers observed have detectable levels of linear, or circular polarisation. Combining our results with those of previous high resolution observations of other OH transitions we are able to investigate various theoretical models for the pumping of OH masers.

scholarly journals Radio and X-ray Study of SNRs in the Magellanic Clouds

1999 ◽  
Vol 192 ◽  
pp. 104-107
Author(s):  
M.D. Filipović ◽  
W. Pietsch ◽  
G. L. White ◽  
F. Haberl ◽  
L. Staveley-Smith ◽  
...  
Keyword(s):  
High Resolution ◽  
Supernova Remnants ◽  
Magellanic Clouds ◽  
Radio Continuum ◽  
H Ii Regions ◽  
Complete Sample ◽  
X Ray ◽  
Compact Array

We present our high-resolution radio-continuum and X-ray study of supernova remnants (SNRs) in the Magellanic Clouds (MCs). These investigations are based on Australia Telescope Compact Array (ATCA) radio-continuum and ROSAT X-ray observations. Our main aim is to study a complete sample of the MC SNRs and H II regions.

scholarly journals Compact Array Mapping of the Nuclear Starburst in NGC 7552

1994 ◽  
Vol 158 ◽  
pp. 355-357
Author(s):  
Duncan A. Forbes ◽  
Ray P. Norris ◽  
Gerry M. Williger ◽  
R. Chris Smith
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Starburst Galaxy ◽  
Angular Momenta ◽  
Lindblad Resonance ◽  
Inner Lindblad Resonance ◽  
Compact Array

We discuss new observations of the starburst galaxy NGC 7552. From optical and near–infrared colour maps we find a red, dusty circumnuclear ring. High-resolution radio mapping from the ATCA reveals the same ring, and a number of bright blobs (probably SNRs). The ring is probably associated with gas and dust which have lost angular momenta due to torques in the bar potential and settled at the inner Lindblad resonance. These circumnuclear starburst rings may be relatively common (when mapped without the obscuring affects of dust) and may play a role in collimating material of a nuclear outflow.

scholarly journals The radio remnant of Supernova 1987A at high frequencies and high resolution

2013 ◽  
Vol 9 (S296) ◽  
pp. 23-26
Author(s):  
G. Zanardo ◽  
L. Staveley-Smith ◽  
C. -Y. Ng ◽  
B. M. Gaensler ◽  
T. M. Potter ◽  
...  
Keyword(s):  
High Resolution ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Radio Image ◽  
High Frequencies ◽  
Compact Source ◽  
Supernova 1987A ◽  
New Radio ◽  
High Dynamic ◽  
Compact Array

AbstractAs the remnant of Supernova (SN) 1987A has been getting brighter over time, new observations at high frequencies have allowed imaging of the radio emission at unprecedented detail. We present a new radio image at 44 GHz of the supernova remnant (SNR), derived from observations performed with the Australia Telescope Compact Array (ATCA) in 2011. The diffraction-limited image has a resolution of 349×225 mas, which is the highest achieved to date in high-dynamic range images of the SNR. We also present a new image at 18 GHz, also derived from ATCA observations performed in 2011, which is super-resolved to 0″.25. The new 44 and 18 GHz images yield the first high-resolution spectral index map of the remnant. The comparison of the 44 GHz image with contemporaneous X-ray and Hα observations allows further investigations of the nature of the remnant asymmetry and sheds more light into the progenitor hypotheses and SN explosion. In light of simple free-free absorption models, we discuss the likelihood of detecting at 44 GHz the possible emission originating from a pulsar wind nebula (PWN) or a compact source in the centre of the remnant.

scholarly journals A high-resolution rotation curve of NGC 6822

2004 ◽  
Vol 220 ◽  
pp. 373-374 ◽  
Author(s):  
W. J. G De Blok ◽  
D. T. F. Weldrake ◽  
F. Walter
Keyword(s):  
Dark Matter ◽  
High Resolution ◽  
Rotation Curve ◽  
Local Group ◽  
Ngc 6822 ◽  
Compact Array

We present a high-resolution rotation curve of the Local Group dwarf irregular NGC 6822, obtained with the Australia Telescope Compact Array. the best curve has a resolution of 8″ or 20 pc and contains some 250 independent points. NGC 6822 is a very dark matter-dominated galaxy. There is no evidence for the presence of a steep density cusp down to scales of ~ 20 pc, in conflict with the predictions of CDM.

scholarly journals Optical spectra of radio planetary nebulae in the small Magellanic cloud

2008 ◽  
pp. 65-70 ◽  
Author(s):  
J.L. Payne ◽  
M.D. Filipovic ◽  
E.J. Crawford ◽  
Horta de ◽  
G.L. White ◽  
...  
Keyword(s):  
South Africa ◽  
High Resolution ◽  
Planetary Nebulae ◽  
Optical Spectra ◽  
Magellanic Cloud ◽  
Radio Sources ◽  
Small Magellanic Cloud ◽  
Preliminary Results ◽  
Central Stars ◽  
Compact Array

We present preliminary results from spectral observations of four (4) candidate radio sources co-identified with known planetary nebulae (PNe) in the Small Magellanic Cloud (SMC). These were made using the Radcliffe 1.9-meter telescope in Sutherland, South Africa. These radio PNe were originally found in Australia Telescope Compact Array (ATCA) surveys of the SMC at 1.42 and 2.37 GHz, and were further confirmed by new high resolution ATCA images at 6 and 3 cm (400 /200 ). Optical PNe and radio candidates are within 200 and may represent a sub- population of selected radio bright objects. Nebular ionized masses of these objects may be 2.6 Mo or greater, supporting the existence of PNe progenitor central stars with masses up to 8 Mo.

scholarly journals Optical spectra of radio planetary nebulae in the large Magellanic Cloud

2008 ◽  
pp. 53-59 ◽  
Author(s):  
J.L. Payne ◽  
M.D. Filipovic ◽  
W.C. Millar ◽  
E.J. Crawford ◽  
Horta de ◽  
...  
Keyword(s):  
South Africa ◽  
High Resolution ◽  
Planetary Nebulae ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Asymptotic Giant Branch ◽  
Emission Lines ◽  
Radio Sources ◽  
Central Stars ◽  
Compact Array

We present 11 spectra from 12 candidate radio sources co-identified with known planetary nebulae (PNe) in the Large Magellanic Cloud (LMC). Originally found in Australia Telescope Compact Array (ATCA) LMC surveys at 1.4, 4.8 and 8.64 GHz and confirmed by new high resolution ATCA images at 6 and 3 cm (4' /2' ), these complement data recently presented for candidate radio PNe in the Small Magellanic Cloud (SMC). Their spectra were obtained using the Radcliff 1.9-meter telescope in Sutherland (South Africa). All of the optical PNe and radio candidates are within 2' and may represent a population of selected radio bright sample only. Nebular ionized masses of these objects are estimated to be as high as 1.8 Mfi, supporting the idea that massive PNe progenitor central stars lose much of their mass in the asymptotic giant branch (AGB) phase or prior. We also identify a sub-population (33%) of radio PNe candidates with prominent ionized iron emission lines.

scholarly journals High-resolution Ammonia Mapping of the Protostellar Core Cha-MMS1

2012 ◽  
Vol 8 (S292) ◽  
pp. 61-61
Author(s):  
Miikka Väisälä ◽  
Jorma Harju ◽  
Maarit Mantere ◽  
Oskari Miettinen ◽  
Malcolm Walmsley
Keyword(s):  
High Resolution ◽  
Velocity Gradient ◽  
Maximum Length ◽  
Dense Gas ◽  
Space Observatory ◽  
Spitzer Space Telescope ◽  
Herschel Space Observatory ◽  
Space Telescope ◽  
Compact Array

AbstractThe nearby protostellar core Cha-MMS1 has been mapped in the NH3 (1, 1) line and the 1.2 cm continuum using the Australia Telescope Compact Array, ATCA. In addition, observations from Spitzer Space Telescope and Herschel Space Observatory are used to help the interpretation. An elongated condensation with a maximum length of 9000 AU is seen in ammonia. The condensation has a clear velocity gradient directed perpendicularly to the axis of elongation. The gradient can be interpreted as rotation around this axis. We suggest that the observed ammonia structure delineates a rotating envelope and dense gas entrained by a very young protostellar outflow.

scholarly journals New HI Observations of the prototype Polar Ring Galaxy NGC 4650A

1997 ◽  
Vol 14 (1) ◽  
pp. 92-95
Author(s):  
Magda Arnaboldi
Keyword(s):  
High Resolution ◽  
Velocity Field ◽  
Central Region ◽  
Near Infrared ◽  
New Technology ◽  
Host Galaxy ◽  
Polar Structure ◽  
Polar Ring ◽  
Compact Array ◽  
Band Image

AbstractNew, high-resolution observations of the HI emission line and 20 cm continuum at the Australia Telescope Compact Array (ATCA) for the prototype polar ring galaxy NGC 4650A are presented. They show the presence of a far more extended HI distribution than previously observed with the VLA, and a very regular velocity field out to a distance of ∼50 kpc. The combined analysis of the HI data with optical and near-infrared (NIR) images argues against previous warp models used to describe the dynamics of this object. Further analysis of the new B-band image obtained at the European Southern Observatories New Technology Telescope (NTT) indicates clearly that the polar structure extends continuously to within about 200 pc of the nucleus of the central host galaxy, ruling out the presence of a ‘hole’ in the central region of this component. The presence of two spiral arms stretching out in the polar disk seems to represent the most likely explanation for the observed morphology and kinematics.

Observations of the spatial structure of interstellar hydrogen

1967 ◽  
Vol 31 ◽  
pp. 45-46
Author(s):  
Carl Heiles
Keyword(s):  
High Resolution ◽  
Spatial Structure ◽  
Velocity Dispersion ◽  
Temperature Variations

High-resolution 21-cm line observations in a region aroundlII= 120°,b11= +15°, have revealed four types of structure in the interstellar hydrogen: a smooth background, large sheets of density 2 atoms cm-3, clouds occurring mostly in groups, and ‘Cloudlets’ of a few solar masses and a few parsecs in size; the velocity dispersion in the Cloudlets is only 1 km/sec. Strong temperature variations in the gas are in evidence.

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