scholarly journals A high resolution H I study of the ISM local to WR 132 and WR 140

1999 ◽  
Vol 193 ◽  
pp. 334-335
Author(s):  
E. Marcelo Arnal
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Joint Action ◽  
Angular Resolution ◽  
Interaction Process ◽  
High Angular Resolution ◽  
Velocity Range ◽  
Matter Distribution

The neutral matter distribution from the interstellar medium located in the vicinity of the galactic WR stars WR 132 and WR 140 has been examined by means of the H I 21-cm line observations obtained with high angular resolution observations. The most interesting discoveries are the presence of huge ovoidal H I minimum spanning the velocity range +13 to +21kms−1 (WR132) and −18 to −7kms−1 (WR 140). These minima were created, very likely, by the joint action of the progenitor of both WR stars and the WR star itself. Inside each cavity, two minima are clearly discernible. The WR star is offset with respect to either the geometrical centre of the main H I void or the inner H I minima. The dual H I minimum geometry observed inside the main H I cavity, a feature also seen in the H I distribution of the ISM located close to other galactic WR stars, may be a consequence of the interaction process itself.

scholarly journals Review of Linked Array Instruments

1989 ◽  
Vol 8 ◽  
pp. 551-552
Author(s):  
R.D. Ekers
Keyword(s):  
High Resolution ◽  
Real Time ◽  
Angular Resolution ◽  
Research Tool ◽  
Aperture Synthesis ◽  
High Angular Resolution ◽  
Radio Telescopes ◽  
Astronomical Research ◽  
Full Operation ◽  
New Facilities

At cm wavelengths aperture synthesis radio-telescopes (arrays of linked antennas which synthesize an image of the sky with high angular resolution) are now becoming the dominant astronomical research tool. Major new facilities such as the VLA are in full operation, others such as the Australia Telescope are nearing completion and a number of telescopes designed to form images in real time have been converted to operate in the aperture synthesis mode (e.g. MOST, Bologna Cross). See Napier et al. (1983) for a review of modern synthesis telescopes. The high resolution, sensitivity and freedom from confusion have led the aperture synthesis telescopes into very diverse astronomical applications.

scholarly journals Introduction to the Joint Commission Meeting on High Resolution Imaging from the Ground

1989 ◽  
Vol 8 ◽  
pp. 545-546
Author(s):  
John Davis
Keyword(s):  
High Resolution ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
High Resolution Imaging ◽  
Wide Range ◽  
High Resolution Images ◽  
Resolution Imaging ◽  
Optical Wavelengths ◽  
To Come ◽  
Very High

As a result of advances in instrumentation and techniques, from radio through to optical wavelengths, we have before us the prospect of producing very high resolution images of a wide range of objects across this entire spectral range. This prospect, and the new knowledge and discoveries that may be anticipated from it, lie behind an upsurge in interest in high resolution imaging from the ground. Several new high angular resolution instruments for radio, infrared, and optical wavelengths are expected to come into operation before the 1991 IAU General Assembly.

scholarly journals High-resolution near-IR imaging of the WCD(+OB) environments: pinwheels

2003 ◽  
Vol 212 ◽  
pp. 121-129 ◽  
Author(s):  
Peter G. Tuthill ◽  
John D. Monnier ◽  
William C. Danchi ◽  
Nils H. Turner
Keyword(s):  
High Resolution ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Dust Formation ◽  
Near Ir ◽  
Ir Imaging ◽  
Fundamental Information

A small number of Wolf-Rayet colliding-wind binaries studied at extremely high angular resolution show elegant dust plumes with an intuitive geometry: that of an Archimedian spiral. A great deal of fundamental information on the binary and the winds is encoded, ultimately teaching us about dust formation and wind-wind collision zones in these fascinating systems. New results are presented summarizing a concerted campaign encompassing a number of systems studied with various techniques over the last five years.

Investigation of the Chromosphere–Corona Interface with the Upgraded Very High Angular Resolution Ultraviolet Telescope (VAULT2.0)

2016 ◽  
Vol 05 (01) ◽  
pp. 1640003 ◽  
Author(s):  
Angelos Vourlidas ◽  
Samuel Tun Beltran ◽  
Georgios Chintzoglou ◽  
Kevin Eisenhower ◽  
Clarence Korendyke ◽  
...  
Keyword(s):  
High Resolution ◽  
Angular Resolution ◽  
Solar Spectrum ◽  
High Angular Resolution ◽  
High Resolution Data ◽  
Lyman Alpha ◽  
And Performance ◽  
White Sands ◽  
Very High ◽  
Resolution Data

Very high angular resolution ultraviolet telescope (VAULT2.0) is a Lyman-alpha (Ly[Formula: see text]; 1216[Formula: see text]Å) spectroheliograph designed to observe the upper chromospheric region of the solar atmosphere with high spatial ([Formula: see text]) and temporal (8[Formula: see text]s) resolution. Besides being the brightest line in the solar spectrum, Ly[Formula: see text] emission arises at the temperature interface between coronal and chromospheric plasmas and may, hence, hold important clues about the transfer of mass and energy to the solar corona. VAULT2.0 is an upgrade of the previously flown VAULT rocket and was launched successfully on September 30, 2014 from White Sands Missile Range (WSMR). The target was AR12172 midway toward the southwestern limb. We obtained 33 images at 8[Formula: see text]s cadence at arc second resolution due to hardware problems. The science campaign was a resounding success, with all space and ground-based instruments obtaining high-resolution data at the same location within the AR. We discuss the science rationale, instrument upgrades, and performance during the first flight and present some preliminary science results.

scholarly journals Near-IR Solar Coronal Observations with New-Technology Reflecting Coronographs

1994 ◽  
Vol 154 ◽  
pp. 603-608
Author(s):  
Raymond N. Smartt ◽  
Serge Koutchmy ◽  
Jacques-Clair NoëNs
Keyword(s):  
High Resolution ◽  
Angular Resolution ◽  
High Sensitivity ◽  
Field Measurements ◽  
Coronal Magnetic Field ◽  
Photon Flux ◽  
Objective Lens ◽  
High Angular Resolution ◽  
Intrinsic Polarization ◽  
Near Ir

Emission-line and K-coronal observations in the IR have the significant advantage of reduced sky brightness compared with the visible, while the effects of seeing are also reduced. Moreover, strong lines are available in the near-IR. Examples of the current capabilities of IR coronal observations using conventional Lyot coronagraphs are discussed briefly. Photometric measurements using the two IR lines of Fe XIII (10,747 Å and 10,798 Å), together with the Fe XIII 3,388 Å line, have provided a valuable electron-density diagnostic, but with low-angular-resolution. The 10,747 Å line has high intrinsic polarization. It has been used for extensive coronal magnetic field measurements, but only the direction of the field, and that with modest angular resolution, has been achieved due basically to flux limitations. Such studies suffer from the lack of high angular resolution and high photon flux. Moreover, the chromatic properties of a singlet objective lens preclude simultaneous observations at widely-differing wavelengths of the important inner coronal region. A coronagraph based on a mirror objective avoids such problems. Further, comparatively high-resolution and high-sensitivity arrays are now available with quantum efficiencies up to 90%. Reflecting coronagraphs with advanced arrays then provide the possibility of obtaining high-resolution images in the infrared to carry out a wide variety of studies crucial to many of the outstanding problems in coronal physics. A program for the development of reflecting coronagraphs is described briefly, with an emphasis on applications to IR coronal studies.

scholarly journals Galactic Plane Surveys at Low Frequencies

2002 ◽  
Vol 199 ◽  
pp. 251-258
Author(s):  
A.R. Taylor
Keyword(s):  
Interstellar Medium ◽  
Atomic Hydrogen ◽  
Angular Resolution ◽  
Spatial Scales ◽  
High Sensitivity ◽  
Hydrogen Gas ◽  
Dimensional Structure ◽  
High Angular Resolution ◽  
Wide Field ◽  
The Galaxy

Until recently, high angular resolution and high sensitivity surveys of the radio emission from the plane of our Galaxy were available only at frequencies of several GHz, where large single dish radio telescopes provide arcminute scale angular resolution. At these frequencies thermal radiation from HII regions and diffuse ionized gas comprise a major component of the Galactic emission. Advances in wide field interferometric imaging techniques now make it possible to carry out high sensitivity surveys of the Galaxy with arcminute scale angular resolution at 1.4 GHz and below. Over the past few years initial synthesis surveys have been made. More ambitious surveys that combined sensitive continuum observations with full polarimetry and images of the 3-dimensional structure of atomic hydrogen gas at pc scales are currently underway in the northern (DRAO) and southern (ATNF) hemispheres. The interstellar medium of the Galaxy contains structure on all spatial scales, and these surveys combined data from aperture synthesis telescopes and signal dish antennas to provide full spatial frequency coverage to the resolution limit. Preliminary results reveal wide-spread features and processes in the the interstellar medium that are not readily visible by other means, including, for example, unusual atomic hydrogen structures related to the vertical transfer of matter and radiation between the disk and halo of the Galaxy, Faraday rotation structures that allow study of the magnetic field and diffuse ionized component in the plane of the Galaxy, and a cold atomic phase of the neutral medium that may provide a link between global shock phenomena in the galaxy and the formation of molecular clouds.

scholarly journals Radio Source Variability as a Tool for Very High Resolution

1994 ◽  
Vol 158 ◽  
pp. 201-203
Author(s):  
N. Shapirovskaya ◽  
O. B. Slee ◽  
P. Hughes ◽  
G. Tsarevsky
Keyword(s):  
High Resolution ◽  
Radio Source ◽  
Time Scale ◽  
High Frequency ◽  
Angular Resolution ◽  
Good Evidence ◽  
High Angular Resolution ◽  
Intrinsic Variability ◽  
Interstellar Plasma ◽  
Very High

If flux density variability is intrinsic to extragalactic sources, then the shortest time scale of the variability yields an extremely high angular resolution. There is, however, good evidence that some of the variability is due to refractive scintillation in our galaxy's interstellar plasma turbulence. The effect, initially discovered at low radio frequencies, is here shown to extend into the GHz band, which, up to now, has been assumed to display only the intrinsic variability. We conclude that further study in both the intermediate and high frequency bands needed to separate the intrinsic and extrinsic components of variability.

scholarly journals Proposal for the Implementation of the ALOHA Up-Conversion Interferometer on the CHARA Telescope Array

2014 ◽  
Vol 03 (03n04) ◽  
pp. 1450008 ◽  
Author(s):  
J. T. Gomes ◽  
L. Grossard ◽  
R. Baudoin ◽  
L. Delage ◽  
F. Reynaud ◽  
...  
Keyword(s):  
High Resolution ◽  
Infrared Radiation ◽  
Angular Resolution ◽  
Spectral Band ◽  
High Angular Resolution ◽  
High Resolution Imaging ◽  
Optical Components ◽  
Telescope Array ◽  
Sum Frequency ◽  
Resolution Imaging

In this paper, we present a new concept of instrument for high resolution imaging in astronomy, involving the sum frequency generation in non-linear waveguides. The aim is to convert the infrared radiation emitted by an astronomical source to the visible spectral domain where the optical components are mature and efficient. We present the main experimental results obtained in laboratory, and propose a new design for this instrument for its implementation on the Center for High Angular Resolution Astronomy (CHARA) telescope array. Preliminary stability and photometric results obtained at CHARA are presented. Using these last measurements, we estimate the limiting magnitudes which could be reached by this interferometer in the H spectral band.

scholarly journals Prospects for High Angular Resolution at Metre to Centimetre Wavelengths

2001 ◽  
Vol 205 ◽  
pp. 412-417
Author(s):  
A.R. Taylor
Keyword(s):  
High Resolution ◽  
Angular Resolution ◽  
Compact Objects ◽  
High Angular Resolution ◽  
New Era ◽  
Long Baseline ◽  
Thermal Radio Emission ◽  
Continuum Sensitivity ◽  
Resolution Imaging ◽  
Thermal Sources

The past ten years has seen very significant advances in high resolution imaging arising from the construction and routine operation of Very Long Baseline Interferometer arrays in the US, Europe and Australia. Coupled with the launch of the first VLBI antennas into earth orbit, angular resolution below a milliarcsecond has been achieved on a large number of compact objects. Nevertheless, while the application of phase referencing to VLBI observations has increased the number of sources that can be imaged by VLBI, the astrophysical impact of interferometry on baselines greater than a few tens of km, has been severely limited by sensitivity. The next decade promises to bring about very significant increases in continuum sensitivity at high angular resolution through new developments in VLBI recording devices to achieve recording bandwidths of 4 to 8 Gbits per second, and by direct optical fibre-linked long baseline arrays. In the following decade, the Square Kilometre Array will herald a new era of high resolution radio astronomy with a factor of 100 sensitivity increase. In addition to vastly increasing the sample of non-thermal sources accessible to VLBI, the SKA will open up high angular resolution imaging to a new regime of astrophysics, by enabling milliarcsecond resolution imaging of thermal radio emission. At wavelengths of a few centimetres the SKA, in combination with next generation space VLBI missions, will allow direct imaging of the x-ray emitting accretion disks in galactic nuclei.

scholarly journals 20cm VLA radio-continuum study of M31: Images and point source catalogues

2012 ◽  
pp. 41-68 ◽  
Author(s):  
T.J. Galvin ◽  
M.D. Filipovic ◽  
E.J. Crawford ◽  
N.F.H. Tothill ◽  
G.F. Wong ◽  
...  
Keyword(s):  
High Resolution ◽  
Angular Resolution ◽  
High Sensitivity ◽  
Radio Continuum ◽  
High Angular Resolution ◽  
Radio Sources ◽  
Large Array ◽  
Complete Sample ◽  
Very Large Array ◽  
Discrete Radio Sources

We present a series of new high-sensitivity and high-resolution radio-continuum images of M31 at ?=20 cm (?=1.4 GHz). These new images were produced by merging archived 20 cm radio-continuum observations from the Very Large Array (VLA) telescope. Images presented here are sensitive to rms=60 ?Jy and feature high angular resolution (<10??). A complete sample of discrete radio sources have been catalogued and analyzed across 17 individual VLA projects. We identified a total of 864 unique discrete radio sources across the field of M31. One of the most prominent regions in M31 is the ring feature for which we estimated total integrated flux of 706 mJy at ?=20 cm. We compare here detected sources to those listed in Gelfand et al. (2004) at ?=92 cm and find 118 sources in common to both surveys. The majority (61%) of these sources exhibit a spectral index of ? <-0.6 indicating that their emission is predominantly non-thermal in nature, that is more typical for background objects.

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