New continuum and polarization observations of the Cygnus Loop with FAST I. Data processing and verification

2021 ◽  
Vol 21 (11) ◽  
pp. 282
Author(s):  
Xiao-Hui Sun ◽  
Mei-Niang Meng ◽  
Xu-Yang Gao ◽  
Wolfgang Reich ◽  
Peng Jiang ◽  
...  
Keyword(s):  
Angular Resolution ◽  
High Sensitivity ◽  
Wide Band ◽  
High Angular Resolution ◽  
Band Frequency ◽  
Cygnus Loop ◽  
Rotation Measure ◽  
Frequency Coverage ◽  
First Time ◽  
Confusion Limit

Abstract We report on the continuum and polarization observations of the Cygnus Loop supernova remnant (SNR) conducted by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). FAST observations provide high angular resolution and high sensitivity images of the SNR, which will help to disentangle its nature. We obtained Stokes I, Q and U maps over the frequency range of 1.03 – 1.46 GHz split into channels of 7.63 kHz. The original angular resolution is in the range of ∼ 3 ′ − ∼ 3 ′ .8 , and we combined all the data at a common resolution of 4 ′ . The temperature scale of the total intensity and the spectral index from the in-band temperature-temperature plot are consistent with previous observations, which validates the data calibration and map-making procedures. The rms sensitivity for the band-averaged total-intensity map is about 20 mK in brightness temperature, which is at the level of confusion limit. For the first time, we apply rotation measure (RM) synthesis to the Cygnus Loop to obtain the polarization intensity and RM maps. The rms sensitivity for polarization is about 5 mK, far below the total-intensity confusion limit. We also obtained RMs of eight extragalactic sources, and demonstrate that the wide-band frequency coverage helps to overcome the ambiguity of RM determinations.

scholarly journals The Molecular Outflow and CO Bullets in HH111

1997 ◽  
Vol 182 ◽  
pp. 141-152 ◽  
Author(s):  
J. Cernicharo ◽  
R. Neri ◽  
Bo Reipurth
Keyword(s):  
High Velocity ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Low Velocity ◽  
Molecular Outflow ◽  
Hh Objects ◽  
Physical Phenomena ◽  
First Time

We present high angular resolution observations of the molecular outflow associated with the optical jet and HH objects of the HH111 system. Interferometric observations in the CO J =2–1 and J =1–0 lines of the high velocity bullets associated with HH111 are presented for the first time. The molecular gas in these high velocity clumps has a moderate kinetic temperature and a mass of a few 10–4 M⊙ per bullet. We favor the view that HH jets and CO bullets, which represent different manifestations of the same physical phenomena, are driving the low-velocity molecular outflow.

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.

Plans for the Australian Synthesis Telescope

1976 ◽  
Vol 3 (1) ◽  
pp. 7-11 ◽  
Author(s):  
K. J. Wellington
Keyword(s):  
Radio Astronomy ◽  
Angular Resolution ◽  
High Sensitivity ◽  
Aperture Synthesis ◽  
High Angular Resolution ◽  
The Past ◽  
New Synthesis

A major requirement of modern radio astronomy is the attainment of the highest possible angular resolution. This high angular resolution should be matched by a high sensitivity and by spectral and polarization capabilities. Study and experience have shown that no form of telescope is more effective in this respect than the aperture synthesis type. The past few years have seen a growing realization amongst astronomers, both here and overseas, of the need for a new synthesis telescope able to observe the full southern sky. This realization has been stimulated by several factors:

scholarly journals η Carinae: high angular resolution continuum, H30α and He30α ALMA images

2020 ◽  
Vol 499 (2) ◽  
pp. 2493-2512
Author(s):  
Zulema Abraham ◽  
Pedro P B Beaklini ◽  
Pierre Cox ◽  
Diego Falceta-Gonçalves ◽  
Lars-Åke Nyman
Keyword(s):  
Angular Resolution ◽  
Line Emission ◽  
High Angular Resolution ◽  
Proper Motions ◽  
Recombination Line ◽  
Compact Source ◽  
Continuum Source ◽  
Velocity Images ◽  
First Time ◽  
Compact Sources

ABSTRACT We present images of η Carinae in the recombination lines H30α and He30α and the underlying continuum with 50 mas resolution (110 au), obtained with ALMA. For the first time, the 230 GHz continuum image is resolved into a compact core, coincident with the binary system position, and a weaker extended structure to the NW of the compact source. Iso-velocity images of the H30α recombination line show at least 16 unresolved sources with velocities between −30 and −65 km s−1 distributed within the continuum source. A NLTE model, with density and temperature of the order of 107 cm−3 and 104 K, reproduce both the observed H30α line profiles and their underlying continuum flux densities. Three of these sources are identified with Weigelt blobs D, C, and B; estimating their proper motions, we derive ejection times (in years) of 1952.6, 1957.1, and 1967.6, respectively, all of which are close to periastron passage. Weaker H30α line emission is detected at higher positive and negative velocities, extending in the direction of the Homunculus axis. The He30α recombination line is also detected with the same velocity of the narrow H30α line. Finally, the close resemblance of the H30α image with that of an emission line that was reported in the literature as HCO+(4–3) led us to identify this line as H40δ instead, an identification that is further supported by modelling results. Future observations will enable to determine the proper motions of all the compact sources discovered in the new high angular resolution data of η Carinae.

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.

Constraining convection across the AGB with high-angular-resolution observations

2018 ◽  
Vol 14 (S343) ◽  
pp. 27-30
Author(s):  
Claudia Paladini ◽  
Fabien Baron ◽  
A. Jorissen ◽  
J.-B. Le Bouquin ◽  
B. Freytag ◽  
...  
Keyword(s):  
Angular Resolution ◽  
Granule Size ◽  
Scaling Relations ◽  
High Angular Resolution ◽  
Large Telescope ◽  
Horizontal Scale ◽  
Very Large Telescope ◽  
Convective Pattern ◽  
Surface Convection ◽  
First Time

AbstractWe present very detailed images of the photosphere of an AGB star obtained with the PIONIER instrument, installed at the Very Large Telescope Interferometer (VLTI). The images show a well defined stellar disc populated by a few convective patterns. Thanks to the high precision of the observations we are able to derive the contrast and granulation horizontal scale of the convective pattern for the first time in a direct way. Such quantities are then compared with scaling relations between granule size, effective temperature, and surface gravity that are predicted by simulations of stellar surface convection.

scholarly journals Classification of Wolf-Rayet stars in NGC 595 in M 33 through high-spatial resolution observations

2003 ◽  
Vol 212 ◽  
pp. 572-573 ◽  
Author(s):  
Pierre Royer ◽  
Ingemar Lundström ◽  
Jean-Marie Vreux
Keyword(s):  
Stellar Population ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Photometric Technique ◽  
H Ii Region ◽  
The One ◽  
First Time ◽  
Rayet Star

NGC 595 is, after NGC 604, the second most luminous H ii region in the Milky Way's neighbouring spiral galaxy M 33. Its Wolf-Rayet star content has mainly been unveiled by two different channels. On the one hand, the stellar population of NGC 595 has been resolved and its WR stars identified through online/off-line H ii λ4686 observations realised with the HST. Nevertheless, due to the limited number of filters used, this did not give any information on the WR spectral subtypes. On the other hand, spectroscopic observations of NGC 595, realised at optical and ultraviolet wavelengths, have enabled the determination of some spectral subtypes, but this time, the lack of angular resolution did not allow to resolve the whole population. Thanks to our photometric technique, based on five dedicated narrow-band filters, we present here a determination of the spectral subtypes of NGC 595 WR stars which for the first time combines high-angular resolution and high-‘spectroscopic’ discrimination capabilities.

scholarly journals Astrometric microlensing with the RadioAstron space mission

2007 ◽  
Vol 3 (S248) ◽  
pp. 387-390
Author(s):  
A. F. Zakharov
Keyword(s):  
Angular Resolution ◽  
High Sensitivity ◽  
Space Mission ◽  
High Angular Resolution ◽  
Radio Telescopes ◽  
Ground Support ◽  
Direct Observations ◽  
The Earth ◽  
Space Agency ◽  
Radio Band

AbstractAccording to a revised schedule of the Russian Space Agency, in October 2008 the 10 m space telescope RadioAstron will be launched in a high eccentric orbit around the Earth. Acting together with ground based radio telescopes, the VLBI interferometer with a ground-space arm will operate. The interferometer will have extraordinary angular resolution of a few microarcsecond (μas) at the shortest wavelength (1.35 cm). Since typical angular scales for gravitational microlensing are at the μas level for cosmological locations of sources and microlenses, in principle there is a chance to resolve microimages and (or) at least, detect astrometrical shift of bright point like images. In particular, gravitationally lensed systems, such as B1600+434, where in radio band a signature of microlensing is found, look suitable for direct observations of microlensing, since microlensing with the RadioAstron interferometer may be detected in the future (considering its high angular resolution and a relatively high sensitivity and assuming a ground support by the advanced radio telescopes).

scholarly journals Numerical Analysis of Micro-Lens Array to the Mid-IR Range

2021 ◽  
Vol 8 (1) ◽  
pp. 11
Author(s):  
Ricardo Gonzalez-Romero ◽  
Guillermo Garcia-Torales ◽  
Marija Strojnik
Keyword(s):  
Angular Resolution ◽  
High Sensitivity ◽  
Radius Of Curvature ◽  
High Angular Resolution ◽  
Ir Detector ◽  
Ir Detectors ◽  
Optical Aberrations ◽  
Lens Array ◽  
Micro Lens Array ◽  
Micro Lens

New interferometric IR techniques have recently been developed to allow Sun-Jupiter-like detections in deep space. These techniques demand a high angular resolution, a high sensitivity towards signal detection buried in noise, and a well-defined bandwidth of spectral resolution. Micro-lens arrangements have helped increase the use of these parameters for IR detectors. In this paper we present a finite element method (FEM)-based simulation of a typical micro-lens array, to be used in mid-IR cameras, where the aperture geometry and radius of curvature are varied for design optimization. Moreover, we show the spot and optical aberrations produced by two types of geometrical arrangements. This procedure could be helpful in improving the IR detector signal in the exoplanets exploration, in systems placed outside of the earth’s atmosphere.

scholarly journals High Angular Resolution Mid-IR Astronomy at Concordia

2005 ◽  
Vol 13 ◽  
pp. 964-964
Author(s):  
Marco Ferrari-Toniolo
Keyword(s):  
Large Scale ◽  
Angular Resolution ◽  
High Sensitivity ◽  
Young Star ◽  
High Angular Resolution ◽  
Star Forming ◽  
Infrared Telescope ◽  
Dry Conditions ◽  
Drift Scan ◽  
Tracking Time

If we concentrate our attention on the study and the evolution of star forming processes rather than on the large scale structure, from the recent use of Large Telescopes in this context there are many examples of great interest. These include the study of the early phases of aggregation of matter (stellar and planet formation), and the late phases of disaggregation during stellar evolution. In Fig 1, a spectacular example is shown of a high resolution image of an edge-on circumstellar disk of a young star (HR4796A), with respect to previous less resolved information (C.Telesco et al, Proc SPIE 4834, 101, 2002). A recent hypothesis of a Large Infrared Telescope called GTA (Grande Telescopio Antartico) has been proposed to the PNRA (Italian Plan for Antarctic Researches). This will require the following characteristics: high angular resolution in the mid-IR domain (large aperture); very high sensitivity (mainly due to the cold, dry conditions of the site); extreme simplicity in design and operational modes. The telescope will be a survey instrument and will be used almost without human intervention. The project examines the construction of a third tower at Dome C with the telescope configured to work in quasi-drift-scan without moving the enclosure and with a limited tracking time. In Fig 1, a sketch of the tower hosting the telescope is shown (M.F-T. et al, Proc SPIE 4836, 165, 2002). A study will be developed to determine the optimum configurations for observing in different bands, from the optical to the sub-mm range, with a refurbishment of the telescope and instrumentation during the summer break.

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