scholarly journals Large Radio Telescopes for Anomalous Microwave Emission Observations

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
E. S. Battistelli ◽  
E. Carretti ◽  
P. de Bernardis ◽  
S. Masi
Keyword(s):  
Angular Resolution ◽  
Signal To Noise Ratio ◽  
Dust Emission ◽  
Merit Function ◽  
Microwave Emission ◽  
High Angular Resolution ◽  
Merit Functions ◽  
Current State ◽  
The World ◽  
Continuum Observation

We discuss in this paper the problem of the Anomalous Microwave Emission (AME) in the light of ongoing or future observations to be performed with the largest fully steerable radio telescope in the world. High angular resolution observations of the AME will enable astronomers to drastically improve the knowledge of the AME mechanisms as well as the interplay between the different constituents of the interstellar medium in our galaxy. Extragalactic observations of the AME have started as well, and high resolution is even more important in this kind of observations. When cross-correlating with IR-dust emission, high angular resolution is also of fundamental importance in order to obtain unbiased results. The choice of the observational frequency is also of key importance in continuum observation. We calculate a merit function that accounts for the signal-to-noise ratio (SNR) in AME observation given the current state-of-the-art knowledge and technology. We also include in our merit functions the frequency dependence in the case of multifrequency observations. We briefly mention and compare the performance of four of the largest radiotelescopes in the world and hope the observational programs in each of them will be as intense as possible.

scholarly journals Modelling the spinning dust emission from LDN 1780

2020 ◽  
Vol 495 (1) ◽  
pp. 1122-1135 ◽  
Author(s):  
Matias Vidal ◽  
Clive Dickinson ◽  
S E Harper ◽  
Simon Casassus ◽  
A N Witt
Keyword(s):  
Angular Resolution ◽  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Microwave Emission ◽  
Spectral Energy ◽  
Frequency Range ◽  
Polycyclic Aromatic ◽  
The Difference ◽  
Dust Grain ◽  
Sd Model

ABSTRACT We study the anomalous microwave emission (AME) in the Lynds Dark Nebula (LDN) 1780 on two angular scales. With publicly available data at an angular resolution of 1°, we studied the spectral energy distribution of the cloud in the 0.408–2997 GHz frequency range. The cloud presents a significant (>20σ) amount of AME, making it one of the clearest examples of AME on 1 ° scales, and its spectrum can be well fitted with a spinning dust (SD) model. We also find at these angular scales that the location of the peak of the emission at lower frequencies (23–70 GHz) differs from the location at the higher frequencies (90–3000 GHz) maps. In addition to the analysis on 1° angular scales, we present data from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at 31 GHz with an angular resolution of 2 arcmin, in order to study the origin of the AME in LDN 1780. We studied morphological correlations between the CARMA map and different infrared tracers of dust emission. We found that the best correlation is with the 70- μm template, which traces warm dust (T ∼ 50 K). Finally, we study the difference in radio emissivity between two locations within the cloud. We measured a factor of ≈6 difference in 31-GHz emissivity. We show that this variation can be explained, using the SD model, by a variation on the dust grain size distribution across the cloud, particularly changing the fraction of polycyclic aromatic hydrocarbon for a fixed total amount of carbon.

scholarly journals First Results from ATCA at Millimetre Wavelengths

2004 ◽  
Vol 221 ◽  
pp. 275-282
Author(s):  
Vincent Minier
Keyword(s):  
Star Formation ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Dust Emission ◽  
Protoplanetary Disks ◽  
High Angular Resolution ◽  
Star Forming ◽  
Star Forming Regions ◽  
First Results ◽  
Excellent Tool

The newly upgraded Australia Telescope Compact Array (ATCA) at millimetre wavelengths is the first millimetre interferometer to be built in the Southern Hemisphere. The full array will be operational in 2004-2005 and will provide arcsec angular resolution at 3 mm and 12 mm. This will be a unique instrument to study at high angular resolution the interstellar chemistry and more generally the star formation process, especially in the bulk of the galactic plane and in the Magellanic Clouds. The upgraded ATCA will also be an excellent tool to detect dust emission from nearby protoplanetary disks. In this paper I will present the first results from the upgraded ATCA at 3 mm and 12 mm. The result review will cover the topics of massive star formation and hot molecular cores dust emission from star-forming regions and detection of protoplanetary disks.

scholarly journals Sensitivity of edge illumination X-ray phase-contrast imaging

2014 ◽  
Vol 372 (2010) ◽  
pp. 20130128 ◽  
Author(s):  
P. C. Diemoz ◽  
M. Endrizzi ◽  
A. Bravin ◽  
I. K. Robinson ◽  
A. Olivo
Keyword(s):  
Theoretical Model ◽  
Phase Contrast ◽  
Angular Resolution ◽  
Signal To Noise Ratio ◽  
Phase Contrast Imaging ◽  
High Angular Resolution ◽  
Contrast Imaging ◽  
Signal To Noise ◽  
X Ray ◽  
Set Up

Recently, we developed a theoretical model that can predict the signal-to-noise ratio for edge-like features in phase-contrast images. This model was then applied for the estimation of the sensitivity of three different X-ray phase-contrast techniques: propagation-based imaging, analyser-based imaging and grating interferometry. We show here how the same formalism can be used also in the case of the edge illumination (EI) technique, providing results that are consistent with those of a recently developed method for the estimation of noise in the retrieved refraction image. The new model is then applied to calculate, in the case of a given synchrotron radiation set-up, the optimum positions of the pre-sample aperture and detector edge to maximize the sensitivity. Finally, an example of the extremely high angular resolution achievable with the EI technique is presented.

scholarly journals Highly structured disk around the planet host PDS 70 revealed by high-angular resolution observations with ALMA

2019 ◽  
Vol 625 ◽  
pp. A118 ◽  
Author(s):  
M. Keppler ◽  
R. Teague ◽  
J. Bae ◽  
M. Benisty ◽  
T. Henning ◽  
...  
Keyword(s):  
Near Infrared ◽  
Angular Resolution ◽  
Dust Emission ◽  
Mass Range ◽  
Position Angle ◽  
Circumstellar Disk ◽  
High Angular Resolution ◽  
Gas Kinematics ◽  
Hydrodynamical Simulations ◽  
Dust Ring

Context. Imaged in the gap of a transition disk and found at a separation of about 195 mas (~22 au) from its host star at a position angle of about 155°, PDS 70 b is the most robustly detected young planet to date. This system is therefore a unique laboratory for characterizing the properties of young planetary systems at the stage of their formation. Aims. We aim to trace direct and indirect imprints of PDS 70 b on the gas and dust emission of the circumstellar disk in order to study the properties of this ~5 Myr young planetary system. Methods. We obtained ALMA band 7 observations of PDS 70 in dust continuum and 12CO (3–2) and combined them with archival data. This resulted in an unprecedented angular resolution of about 70 mas (~8 au). Results. We derive an upper limit on circumplanetary material at the location of PDS 70 b of ~0.01 M⊕ and find a highly structured circumstellar disk in both dust and gas. The outer dust ring peaks at 0.65′′ (74 au) and reveals a possible second unresolved peak at about 0.53′′ (60 au). The integrated intensity of CO also shows evidence of a depletion of emission at ~0.2′′ (23 au) with a width of ~0.1′′ (11 au). The gas kinematics show evidence of a deviation from Keplerian rotation inside ≲0.8′′ (91 au). This implies a pressure gradient that can account for the location of the dust ring well beyond the location of PDS 70 b. Farther in, we detect an inner disk that appears to be connected to the outer disk by a possible bridge feature in the northwest region in both gas and dust. We compare the observations to hydrodynamical simulations that include a planet with different masses that cover the estimated mass range that was previously derived from near-infrared photometry (~5–9 MJup). We find that even a planet with a mass of 10 MJup may not be sufficient to explain the extent of the wide gap, and an additional low-mass companion may be needed to account for the observed disk morphology.

scholarly journals High Angular Resolution with Rotation Shearing Interferometers: Preliminary Results and Future Potentials

1982 ◽  
Vol 67 ◽  
pp. 207-211
Author(s):  
F. Roddier ◽  
C. Roddier
Keyword(s):  
Binary Stars ◽  
Angular Resolution ◽  
Signal To Noise Ratio ◽  
Speckle Noise ◽  
Speckle Interferometry ◽  
High Angular Resolution ◽  
List Type ◽  
Type Number ◽  
Stellar Diameters ◽  
Visual Measurements

Compared to speckle-interferometry, amplitude-interferometry has the following advantages: (1) The amplitude of the object Fourier components is insensitive to both turbulence and telescope induced aberrations, permitting an accurate calibration of visibility curves,(2) Interferograms are free from speckle noise, permitting a better signal-to-noise ratio on bright sources,(3) Information can be retrieved from fewer exposures (including complete image reconstruction),(4) Accurate visual measurements of stellar diameters and of the angular spacing of binary stars can be easily performed.

scholarly journals High Angular Resolution Studies of Disks-the Millimetre

2004 ◽  
Vol 221 ◽  
pp. 381-388
Author(s):  
David J. Wilner
Keyword(s):  
Main Sequence ◽  
Angular Resolution ◽  
Dust Emission ◽  
Physical Models ◽  
High Angular Resolution ◽  
Main Sequence Stars ◽  
Low Mass

I briefly review progress in high angular resolution observations of disks at millimetre wavelengths, with a focus on dust continuum observations of the disks surrounding low mass pre-main-sequence stars. I summarize the utility of observations at millimetre wavelengths, where dust emission is largely optically thin, and I touch on several recent directions, including imaging surveys using interferometers, testing physical models of disks with resolved observations, and the complexities introduced by stellar multiplicity.

scholarly journals Observing protoplanetary discs with the Square Kilometre Array – I. Characterizing pebble substructure caused by forming planets

2020 ◽  
Vol 498 (4) ◽  
pp. 5116-5127
Author(s):  
John D Ilee ◽  
Cassandra Hall ◽  
Catherine Walsh ◽  
Izaskun Jiménez-Serra ◽  
Christophe Pinte ◽  
...  
Keyword(s):  
Angular Resolution ◽  
Dust Emission ◽  
Image Plane ◽  
Raw Material ◽  
High Angular Resolution ◽  
High Fidelity ◽  
Dust Grains ◽  
Square Kilometre Array ◽  
A Current ◽  
Protoplanetary Discs

ABSTRACT High-angular-resolution observations of discs at mm wavelengths (on scales of a few au) are now commonplace, but there is a current lack of a comparable angular resolution for observations at cm wavelengths. This presents a significant barrier to improving our understanding of planet formation, in particular how dust grains grow from mm to cm sizes. In this paper, we examine the ability of the Square Kilometre Array (SKA) to observe dust substructure in a young, planet-forming disc at cm wavelengths. We use dusty hydrodynamics and continuum radiative transfer to predict the distribution and emission of 1-cm dust grains (or pebbles) within the disc, and simulate continuum observations with the current SKA1-MID design baseline at frequencies of 12.5 GHz (Band 5b, ∼2.4 cm) on 5–10 au scales. The SKA will provide high-fidelity observations of the cm dust emission substructure in discs for integration times totalling hundreds of hours. Radial structure can be obtained at a sufficient resolution and S/N from shorter (tens of hours) integration times by azimuthal averaging in the image plane. By modelling the intensity distribution directly in the visibility plane, it is possible to recover a similar level of (axisymmetric) structural detail from observations with integration times one to two orders of magnitude lower than required for high-fidelity imaging. Our results demonstrate that SKA1-MID will provide crucial constraints on the distribution and morphology of the raw material for building planets, the pebbles in protoplanetary discs.

scholarly journals Measuring Stars with High Angular Resolution: Current Status and Future Prospects

1985 ◽  
Vol 111 ◽  
pp. 193-208
Author(s):  
John Davis
Keyword(s):  
Angular Resolution ◽  
Modern Technology ◽  
Surface Fluxes ◽  
Current Status ◽  
High Angular Resolution ◽  
Long Baseline ◽  
Stellar Interferometer ◽  
Current State ◽  
The University

The current state of knowledge of angular diameters of stars is reviewed and, based on this review and the requirements for the determination of surface fluxes, effective temperatures, radii and masses, targets of sensitivity, angular resolution and accuracy for future programs of stellar angular diameter measurements are established. Long baseline interferometry is the only technique with the potential to meet all the targets. The necessary improvements in sensitivity, angular resolution and accuracy are promised by the approach adopted in the modern Michelson stellar interferometer under development at the University of Sydney and the prototype instrument, which is currently nearing completion, is briefly described to illustrate how the atmospheric and mechanical problems which have inhibited the development of amplitude interferometry may be overcome using modern technology. This program together with the developments taking place at CERGA lead to the conclusion that the prospects for contributions by high angular resolution measurements to the determination of fundamental stellar quantities during the next decade are excellent.

scholarly journals Concept for an X-ray telescope system with an angular resolution booster

2019 ◽  
Vol 71 (5) ◽  
Author(s):  
Yoshitomo Maeda ◽  
Ryo Iizuka ◽  
Takayuki Hayashi ◽  
Toshiki Sato ◽  
Nozomi Nakaniwa ◽  
...  
Keyword(s):  
Angular Resolution ◽  
Imaging System ◽  
Signal To Noise Ratio ◽  
Effective Area ◽  
High Energy ◽  
High Angular Resolution ◽  
Coded Aperture ◽  
X Ray ◽  
Modulation Collimator ◽  
Mirror Focus

ABSTRACT We present a concept for an X-ray imaging system with a high angular resolution and moderate sensitivity. In this concept, a two-dimensional detector, i.e., an imager, is put at a slightly out-of-focus position of the focusing mirror, rather than just at the mirror focus, as in the standard optics, to capture miniature images of objects. In addition, a set of multi-grid masks (or a modulation collimator) is installed in front of the telescope. We find that the masks work as a coded aperture camera and that they boost the angular resolution of the focusing optics. The major advantage of this concept is that a much better angular resolution, having an order of 2–3 or more than in the conventional optics, is achievable, while a high throughput (large effective area) is maintained, which is crucial in photon-limited high-energy astronomy, because any type of mirrors, including lightweight reflective mirrors, can be employed in our concept. If the signal-to-noise ratio is sufficiently high, we estimate that angular resolutions at the diffraction limit of 4″ and 0.″4 at ∼7 keV can be achieved with a pair of masks at distances of 1 m and 100 m, respectively.

scholarly journals Small-scale properties of Class 0 protostars from the CALYPSO IRAM-PdBI survey

2015 ◽  
Vol 11 (S315) ◽  
pp. 114-117
Author(s):  
Anaëlle Maury ◽  
Philippe André ◽  
Sébastien Maret ◽  
Arnaud Belloche ◽  
Claudio Codella ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Angular Resolution ◽  
Dust Emission ◽  
Continuum Emission ◽  
Small Scale ◽  
High Angular Resolution ◽  
Multiple Systems ◽  
Small Scales ◽  
Molecular Lines ◽  
Scale Properties

AbstractBecause the formation of protostars is believed to be closely tied to the angular momentum problem of star formation, characterizing the properties of the youngest disks around Class 0 objects is crucial. However, not much is known on the structure of the youngest protostellar envelopes, on the small scales at which disks and multiple systems are observed around more evolved YSOs, due to a lack of comprehensive high angular resolution observations (probing <100 AU). In order to tackle this issue, we conducted a large observing program with the IRAM Plateau de Bure interferometer (PdBI): the CALYPSO survey, providing us with detailed maps of molecular lines and millimeter continuum emission, probing scales down to ~30–50 au towards a sample of 17 Class 0 protostars. Here we present our analysis of the CALYPSO dust continuum emission maps, constraining disk properties of the Class 0 protostars in our sample. We show that large, r > 50 au, disk structures are not observed in most Class 0 protostars from our sample, which can be described by various envelope models reproducing satisfactorily the intensity distribution of the dust emission at all scales from 50 au to 5000 au.

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