Closure phase in high-resolution optical imaging

Baldwin, John E.; Haniff, Christopher A.; Mackay, Craig D.; Warner, P. J.

doi:10.1038/320595a0

Cited by 159 publications

(117 citation statements)

References 7 publications

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“…Application at higher frequencies was first mentioned by Rogstad (1968), but only much later carried out in the visible/infrared through aperture masking experiments (Baldwin et al 1986a;Haniff et al 1987a;Readhead et al 1988;Haniff et al 1989). Currently three separateelement interferometers have succeeded in obtaining closure phase measurements in the visible/infrared, first at COAST (Baldwin et al 1996a), soon after at NPOI (Benson et al 1997a), and most recently at IOTA (Traub, 2002).…”

Section: Closure Phases Considermentioning

confidence: 99%

“…The interference pattern formed thus simulates one from an array of telescopes combined like a Young's multi-slit experiment. Baldwin et al (1986b) and Haniff et al (1987b) showed how aperture masking in the visible yield data identical to that expected for an imaging array, and produced images of binary stars using closurephase imaging. This group, based at the University of Cambridge, England, would soon begin developing the COAST interferometer, which would succeed in producing the first image with an aperture synthesis optical array (Baldwin et al, 1996b).…”

Section: Brief Historical Overviewmentioning

confidence: 99%

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Optical interferometry in astronomy

2003

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Abstract. Here I review the current state of the field of optical stellar interferometry, concentrating on ground-based work although a brief report of space interferometry missions is included. We pause both to reflect on decades of immense progress in the field as well as to prepare for a new generation of large interferometers just now being commissioned (most notably, the CHARA, Keck and VLT Interferometers). First, this review summarizes the basic principles behind stellar interferometry needed by the lay-physicist and general astronomer to understand the scientific potential as well as technical challenges of interferometry. Next, the basic design principles of practical interferometers are discussed, using the experience of past and existing facilities to illustrate important points. Here there is significant discussion of current trends in the field, including the new facilities under construction and advanced technologies being debuted. This decade has seen the influence of stellar interferometry extend beyond classical regimes of stellar diameters and binary orbits to new areas such as mapping the accretion disks around young stars, novel calibration of the Cepheid Period-Luminosity relation, and imaging of stellar surfaces. The third section is devoted to the major scientific results from interferometry, grouped into natural categories reflecting these current developments. Lastly, I consider the future of interferometry, highlighting the kinds of new science promised by the interferometers coming on-line in the next few years. I also discuss the longer-term future of optical interferometry, including the prospects for space interferometry and the possibilities of large-scale ground-based projects. Critical technological developments are still needed to make these projects attractive and affordable. †

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Section: Closure Phases Considermentioning

confidence: 99%

Section: Brief Historical Overviewmentioning

confidence: 99%

Optical interferometry in astronomy

2003

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“…The recovery of di †raction-limited maps was also possible with the help of self-calibration methods such as the maximum entropy method (Gull & Skilling 1984 ;Sivia 1987) or CLEAN algorithm 1974. The signal-to-noise ratio (S/N) (Hogbom advantages of sparse-aperture observations for bright sources have been exploited previously (e.g., Baldwin et al 1986 ;Hani † et al 1987 ;Roddier 1988), while a more detailed description of this particular apparatus and technique may be found in Monnier et al (1999) and . An observing log of near-IR observations is given in Table 1, showing the dates, Ðlters, and stellar phases (J. A.…”

Section: Near-infrared Interferometrymentioning

confidence: 99%

Near‐ and Mid‐Infrared Subarcsecond Structure of the Dusty Symbiotic Star R Aquarii

Tuthill

Danchi

Hale

et al. 2000

ApJ

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The results of a high-resolution interferometric campaign targeting the symbiotic long-period variable (LPV) R Aqr are reported. With both near-infrared measurements on baselines out to 10 m and midinfrared data extending to 32 m, we have been able to measure the characteristic sizes of regions from the photosphere of the LPV and its extended molecular atmosphere out to the cooler circumstellar dust shell. The near-infrared data were taken using aperture-masking interferometry on the Keck I telescope and show R Aqr to be partially resolved for wavelengths out to 2.2 km but with a marked enlargement, possibly due to molecular opacity, at 3.1 km. Mid-infrared interferometric measurements were obtained with the Univeristy of California, Berkeley, infrared spatial interferometer (ISI) operating at 11.15 km from 1992 to 1999. Although this data set is somewhat heterogeneous with incomplete coverage of the Fourier plane and sampling of the pulsation cycle, clear changes in the mid-infrared brightness distribution were observed, both as a function of position angle on the sky and as a function of pulsation phase. Spherically symmetric radiative transfer calculations of uniform-outÑow dust shell models produce brightness distributions and spectra which partially explain the data ; however, limitations to this approximation are noted. Evidence for signiÐcant deviation from circular symmetry was found in the mid-infrared and more tentatively at 3.08 km in the near-infrared ; however, no clear detection of binarity or of non-LPV elements in the symbiotic system is reported.

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“…To measure the closure phase, we took the phase of the complex triple product (bispectrum, Baldwin et al 1986). The instrumental closure phase of IONIC3 drifted by less than 1 degree over many hours owing to the miniature dimensions of the integrated optics component.…”

Section: Observationsmentioning

confidence: 99%

“…The observations performed with the WHT used the nonredundant aperture masking method (Baldwin et al 1986;Haniff et al 1987) and employed a five-hole linear aperture mask. Filters centred on both 7000 Å and 9050 Å were used to select the observing waveband; only the 7000 Å data are presented in this paper.…”

Section: Wht Data From 1997mentioning

confidence: 99%

Radiative hydrodynamics simulations of red supergiant stars

Chiavassa

Haubois

Young

et al. 2010

A&A

125

130

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Context. The red supergiant (RSG) Betelgeuse is an irregular variable star. Convection may play an important role in understanding this variability. Interferometric observations can be interpreted using sophisticated simulations of stellar convection. Aims. We compare the visibility curves and closure phases obtained from our 3D simulation of RSG convection with CO5BOLD to various interferometric observations of Betelgeuse from the optical to the H band to characterize and measure the convection pattern on this star. Methods. We use a 3D radiative-hydrodynamics (RHD) simulation to compute intensity maps in different filters and thus derive interferometric observables using the post-processing radiative transfer code OPTIM3D. The synthetic visibility curves and closure phases are compared to observations. Results. We provide a robust detection of the granulation pattern on the surface of Betelgeuse in both the optical and the H band based on excellent fits to the observed visibility points and closure phases. We determine that the Betelgeuse surface in the H band is covered by small to medium scale (5−15 mas) convection-related surface structures and a large (≈30 mas) convective cell. In this spectral region, H 2 O molecules are the main absorbers and contribute to both the small structures and the position of the first null of the visibility curve (i.e., the apparent stellar radius).

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Closure phase in high-resolution optical imaging

Cited by 159 publications

References 7 publications

Optical interferometry in astronomy

Optical interferometry in astronomy

Near‐ and Mid‐Infrared Subarcsecond Structure of the Dusty Symbiotic Star R Aquarii

Radiative hydrodynamics simulations of red supergiant stars

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