共查询到20条相似文献，搜索用时 31 毫秒
1.
J.-P. Berger F. Malbet F. Baron A. Chiavassa G. Duvert M. Elitzur B. Freytag F. Gueth S. H?nig J. Hron H. Jang-Condell J.-B. Le Bouquin J.-L. Monin J. D. Monnier G. Perrin B. Plez T. Ratzka S. Renard S. Stefl E. Thiébaut K. R. W. Tristram T. Verhoelst S. Wolf J. Young 《Astronomy and Astrophysics Review》2012,20(1):1-55
The number of publications of aperture-synthesis images based on optical long-baseline interferometry measurements has recently increased due to easier access to visible and infrared interferometers. The interferometry technique has now reached a technical maturity level that opens new avenues for numerous astrophysical topics requiring milli-arcsecond model-independent imaging. In writing this paper our motivation was twofold: (1) review and publicize emblematic excerpts of the impressive corpus accumulated in the field of optical interferometry image reconstruction; (2) discuss future prospects for this technique by selecting four representative astrophysical science cases in order to review the potential benefits of using optical long-baseline interferometers. For this second goal we have simulated interferometric data from those selected astrophysical environments and used state-of-the-art codes to provide the reconstructed images that are reachable with current or soon-to-be facilities. The image-reconstruction process was ??blind?? in the sense that reconstructors had no knowledge of the input brightness distributions. We discuss the impact of optical interferometry in those four astrophysical fields. We show that image-reconstruction software successfully provides accurate morphological information on a variety of astrophysical topics and review the current strengths and weaknesses of such reconstructions. We investigate how to improve image reconstruction and the quality of the image possibly by upgrading the current facilities. We finally argue that optical interferometers and their corresponding instrumentation, existing or to come, with six to ten telescopes, should be well suited to provide images of complex sceneries. 相似文献
2.
F. Malbet 《Astrophysics and Space Science》2003,286(1-2):131-144
The study of Young Stellar Objects (YSOs) is one of the most exciting topics that can be undertaken by long baseline optical
interferometry. The magnitudes of these objects are at the edge of capabilities of current optical interferometers, limiting
the studies to a few dozen, but are well within the capability of coming large aperture interferometers like the VLT Interferometer,
the Keck Interferometer, the Large Binocular Telescope or 'OHANA. The milli-arcsecond spatial resolution reached by interferometry
probes the very close environment of young stars, down to a tenth of an astronomical unit. In this paper, I review the different
aspects of star formation that can be tackled by interferometry: circumstellar disks, multiplicity, jets. I present recent
observations performed with operational infrared interferometers, IOTA, PTI and ISI, and I show why in the next future one
will extend these studies with large aperture interferometers.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
S. Wolf F. Malbet R. Alexander J.-P. Berger M. Creech-Eakman G. Duchêne A. Dutrey C. Mordasini E. Pantin F. Pont J.-U. Pott E. Tatulli L. Testi 《Astronomy and Astrophysics Review》2012,20(1):1-83
We present a review of the interplay between the evolution of circumstellar disks and the formation of planets, both from the perspective of theoretical models and dedicated observations. Based on this, we identify and discuss fundamental questions concerning the formation and evolution of circumstellar disks and planets which can be addressed in the near future with optical and infrared long-baseline interferometers. Furthermore, the importance of complementary observations with long-baseline (sub)millimeter interferometers and high-sensitivity infrared observations is outlined. 相似文献
4.
M. Vannier R. G. Petrov B. Lopez F. Millour 《Monthly notices of the Royal Astronomical Society》2006,367(2):825-837
We present the high angular resolution technique of colour-differential interferometry for direct detection of extrasolar giant planets (EGPs). The measurement of differential phase with long-baseline ground-based interferometers in the near-infrared could allow the observation of several hot giant extrasolar planets in tight orbit around the nearby stars, and thus yield their low- or mid-resolution spectroscopy, complete orbital data set and mass. Estimates of potentially achievable signal-to-noise ratios are presented for a number of planets already discovered by indirect methods. The limits from the instrumental and atmospheric instability are discussed, and a subsequent observational strategy is proposed. 相似文献
5.
回顾了光干涉与综合孔径技术发展的历史和现状，分析了国际上用于天文观测的一些著名地基和空基光干涉仪的技术特点，介绍了光干涉与综合孔径技术的发展，以及在光学综合孔径技术领域所发展的光纤与集成光学等新技术，简要介绍了近年来我国开展光干涉与综合孔径技术的进展情况。针对光干涉与综合孔径技术的发展前景和国内外技术发展趋势，发出了加快发展我国光干涉与综合孔径技术的呼吁。 相似文献
6.
7.
Benjamin F. Lane 《Astrophysics and Space Science》2003,286(1-2):177-183
Modern long-baseline interferometers are capable of resolving stellar diameters in the range of one to several milli-arcseconds
with measurement precision approaching a few percent. This level of precision allows astronomers to directly resolve diameter
changes associated with pulsation for various classesc of stars, including Cepheids and Miras. For several nearby Cepheids
itis relatively straightforward to apply a Baade-Wesselink analysis and hence directly measure the distance to the Cepheid
with a high degree of precision. This field is still quite new; I expect that in the near term several new interferometers
will provide direct Cepheid distances to perhaps a few tens of Galactic Cepheids. However, equally important will be direct
measurements of the atmospheric properties (in particular limb darkening) of these stars. Such measurements should help reduce
the considerable systematic uncertainties that remain.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
S. Kraus 《Astronomische Nachrichten》2014,335(1):51-58
Modern optical spectrographs and optical interferometers push the limits in the spectral and spatial regime, providing important new tools for the exploration of the Universe. In this contribution I outline the complementary nature of spectroscopic and interferometric observations and discuss different strategies for combining such data. Most remarkable, the latest generation of “spectro‐interferometric” instruments combine the milliarcsecond angular resolution achievable with interferometry with spectral capabilities, enabling direct constraints on the distribution, density, kinematics, and ionization structure of the gas component in protoplanetary disks. I will present some selected studies from the field of star‐ and planet formation and hot star research in order to illustrate these fundamentally new observational opportunities. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
9.
We derive a generalized van Cittert-Zernike (vC-Z) theorem for radio astronomy that is valid for partially polarized sources over an arbitrarily wide field of view (FoV). The classical vC-Z theorem is the theoretical foundation of radio astronomical interferometry, and its application is the basis of interferometric imaging. Existing generalized vC-Z theorems in radio astronomy assume, however, either paraxiality (narrow FoV) or scalar (unpolarized) sources. Our theorem uses neither of these assumptions, which are seldom fulfiled in practice in radio astronomy, and treats the full electromagnetic field. To handle wide, partially polarized fields, we extend the two-dimensional (2D) electric field (Jones vector) formalism of the standard 'Measurement Equation' (ME) of radio astronomical interferometry to the full three-dimensional (3D) formalism developed in optical coherence theory. The resulting vC-Z theorem enables full-sky imaging in a single telescope pointing, and imaging based not only on standard dual-polarized interferometers (that measure 2D electric fields) but also electric tripoles and electromagnetic vector-sensor interferometers. We show that the standard 2D ME is easily obtained from our formalism in the case of dual-polarized antenna element interferometers. We also exploit an extended 2D ME to determine that dual-polarized interferometers can have polarimetric aberrations at the edges of a wide FoV. Our vC-Z theorem is particularly relevant to proposed, and recently developed, wide FoV interferometers such as Low Frequency Array (LOFAR) and Square Kilometer Array (SKA), for which direction-dependent effects will be important. 相似文献
10.
郭红锋 《紫金山天文台台刊》2003,(1)
本文简单介绍了光干涉与综合孔径技术发展的历史、国际上用于天文观测的一些著名光干涉仪的技术特点和进展、以及近年来我国开展的与光干涉 ,综合孔径技术有关的工作 ,最后简要介绍了在光学综合孔径技术领域所发展的光纤与集成光学等新技术 相似文献
11.
F. Patru D. Mourard O. Lardière S. Lagarde 《Monthly notices of the Royal Astronomical Society》2007,376(3):1047-1053
Long baseline interferometry is now a mature technique in the optical domain. Current interferometers are, highly limited in, number of subapertures and concepts are being developed for future generations of very large optical arrays and especially with the goal of direct imaging. In this paper, we study the effects of introducing single-mode fibres in direct imaging optical interferometers. We show how the flexibility of optical fibres is well adapted to the pupil densification scheme. We study the effects of the truncation of the Gaussian beams in the imaging process, either in the Fizeau mode or in the densified pupil mode or in the densified image mode. Finally, in the pupil densification configuration, we identify an optimum of the diaphragm width. This optimum maximizes the on-axis irradiance and corresponds to a trade-off between the loss of transmission and the efficiency of the densification. 相似文献
12.
Intensity interferometry removes the stringent requirements on mechanical precision and atmospheric corrections that plague all amplitude interferometry techniques at the cost of severely limited sensitivity. A new idea we recently introduced, very high redundancy, alleviates this problem. It enables the relatively simple construction (∼1 cm mechanical precision) of a ground-based astronomical facility able to transform a two-dimensional field of point-like sources to a three-dimensional distribution of microarcsec resolved systems, each imaged in several optical bands. Each system will also have its high-resolution residual timing, high-quality (inside each band) spectra and light curve, emergent flux, effective temperature, polarization effects and perhaps some thermodynamic properties, all directly measured. All the above attributes can be measured in a single observation run of such a dedicated facility. We conclude that after three decades of abandonment, optical intensity interferometry deserves another review, also as a ground-based alternative to the science goals of space interferometers. 相似文献
13.
I try to present a small view of the properties and issues related to astronomical interferometry observations. I recall a bit of history of the technique, give some basic assessments to the principle of interferometry, and finally, describe physical processes and limitations that affect optical long baseline interferometry and which are, in general, very useful for everyday work. Therefore, this text is not intended to perform strong demonstrations and show accurate results, but rather to transmit the general “feeling” one needs to have to not be destabilised by the first contact to real world interferometry. 相似文献
14.
Narrow-angle astrometry with long-baseline infrared interferometers can provide extremely high accuracies as required for indirect planet detection. Narrow-angle astrometric interferometry exploits the properties of atmospheric turbulence over fields smaller than the interferometer baseline divided by the atmospheric scale height. For such fields, accuracy is linear with star separation, and nearly inversely proportional to baseline length. To exploit these properties, the interferometer observes a relatively bright (< 13 magk) target in the near infrared at 2.2m, and uses phase referencing to find a reference star within the 2.2-m isoplanatic patch. With this technique faint references can be found for most targets. With baselines > 100 m, which also minimize photon-noise errors, and with careful control of systematic errors by using laser metrology, accuracies of tens of microarcseconds/hour should be possible.Paper presented at the Conference onPlanetary Systems: Formation, Evolution, and Detection held 7–10 December, 1992 at CalTech, Pasadena, California, U.S.A. 相似文献
15.
16.
Browne Patnaik Wilkinson & Wrobel 《Monthly notices of the Royal Astronomical Society》1998,293(3):257-287
We present a catalogue of 781 compact radio sources in the declination range 0° ≤ δB1950 ≤ +20° whose positions have been measured to an rms accuracy of about 14 mas with the Very Large Array (VLA). These sources are primarily intended for use as phase calibration sources for the Jodrell Bank MERLIN. However, they will also be suitable as phase calibrators for the VLA and can be considered as candidate phase calibrators for very long-baseline interferometry (VLBI) networks. 相似文献
17.
G. S. Tucker J. Kim P. Timbie S. Ali L. Piccirillo C. Calderon 《New Astronomy Reviews》2003,47(11-12):1173
Bolometric interferometry is not a new idea, but this technique has not been demonstrated at millimeter wavelengths. The millimeter-wave bolometric interferometer combines the advantages of two well-developed technologies – interferometers and bolometric detectors – and will open a new region of sensitivity and angular resolution not previously accessible to other instruments. 相似文献
18.
Enrico Lorenzini Claudio Bombardelli Mario Cosmo Martin Harwit David Leisawitz Rodger Farley Stephen Rinehart David Quinn David Miller 《Astrophysics and Space Science》2006,302(1-4):225-239
Through the continuing development of improved detectors and detector arrays, far-infrared/submillimeter astronomical space
missions have had enormous successes in recent years. Despite these advances, the diffraction-limited angular resolving power
has remained virtually constant. The advent of telescopes with apertures of several meters will improve this capability, but
will still leave image resolution many orders of magnitude poorer than in most other spectral ranges. Here we point out that
the only foreseeable way to improve image quality to rival that of modern optical telescopes will be with interferometers
whose light collectors are connected by tethers. After making the scientific case for high spatial resolution far-infrared/submillimeter
imaging and the use of interferometry as the most immediate way of producing results, we discuss recent advances in dynamic
analysis and control of tethered formations, and argue that the further development and testing of tethers in space is a first
step toward providing improved far-infrared/submillimeter angular resolution and astronomical image quality. 相似文献
19.
Philippe Stee 《Astrophysics and Space Science》2003,286(1-2):225-236
Interferometry in the visible provides milliarcsecond spatial resolution and thus has been used for studying the circumstellar
environment of active hot stars. In this paper I will illustrate how the visibility modulus and phase can be used to better
constrain the physics of Be disks through results from the VLA, the MkII and the GI2T interferometers. I will insist on the
importance and the potential of coupling high angular resolution with high spectral resolution to the study of Be shells.
Finally I will present a possible study of the circumstellar disk of Be stars using the VLTI.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
J.W. Keen D_f. Buscher P.J. Warner 《Monthly notices of the Royal Astronomical Society》2001,326(4):1381-1386
We use a numerical simulation to investigate the effectiveness of pinhole spatial filters for optical/IR interferometers and to compare them with single-mode optical fibre spatial filters and interferometers without spatial filters. We show that fringe visibility measurements in interferometers containing spatial filters are much less affected by changing seeing conditions than equivalent measurements without spatial filters. This reduces visibility calibration uncertainties, and hence can reduce the need for frequent observations of separate astronomical sources for calibration of visibility measurements. We also show that spatial filters can increase the signal-to-noise ratios (SNRs) of visibility measurements and that pinhole filters give SNRs within 17 per cent of the values obtained with single-mode fibres for aperture diameters up to 3 r 0 . Given the simplicity of the use of pinhole filters we suggest that it represents a competitive, if not optimal, technique for spatial filtering in many current and next generation interferometers. 相似文献