Optical interferometry in astronomy

Monnier, John D.

doi:10.1088/0034-4885/66/5/203

Cited by 288 publications

(256 citation statements)

References 240 publications

(382 reference statements)

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“…The resulting computational load is substantially lighter and allows for faster and more complete Monte Carlo searches. A detailed review of optical interferometry in astronomy can be found in Monnier (2003). A detailed discussion of phases in particular is continued in Monnier (2007), including expansive discussions on closure phase, and more esoteric observables possible with optical interferometers, such as differential closure phase, closure differential phase, and closure amplitudes.…”

Section: Observational Quantities Predictionsmentioning

confidence: 99%

Interferometric observations of rapidly rotating stars

Belle

2012

Astron Astrophys Rev

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Optical interferometry provides us with a unique opportunity to improve our understanding of stellar structure and evolution. Through direct observation of rotationally distorted photospheres at sub-milliarcsecond scales, we are now able to characterize latitude dependencies of stellar radius, temperature structure, and even energy transport. These detailed new views of stars are leading to revised thinking in a broad array of associated topics, such as spectroscopy, stellar evolution, and exoplanet detection. As newly advanced techniques and instrumentation mature, this topic in astronomy is poised to greatly expand in depth and influence.

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Section: Observational Quantities Predictionsmentioning

confidence: 99%

Interferometric observations of rapidly rotating stars

Belle

2012

Astron Astrophys Rev

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“…However, the absolute value of the phase is lost because of random atmospheric perturbations. By adding the phases of the fringes measured for each baseline over a 3-telescope configuration, one can measure the closure phase, which is insensitive to atmospheric disturbances (Jennison 1958;Monnier 2003). The closure phase includes part of the Fourier phase information, and is related to the global asymmetry of the emission: a point-symmetric object has a zero closure phase.…”

Section: Image Reconstruction Processmentioning

confidence: 99%

A low optical depth region in the inner disk of the Herbig Ae star HR 5999

Benisty

Renard

Natta

et al. 2011

A&A

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Context. Circumstellar disks surrounding young stars are known to be the birthplaces of planetary systems, and the innermost astronomical unit is of particular interest. Near-infrared interferometric studies have revealed a complex morphology for the close environment surrounding Herbig Ae stars. Aims. We present new long-baseline spectro-interferometric observations of the Herbig Ae star, HR 5999, obtained in the H and K bands with the AMBER instrument at the VLTI, and aim to produce near-infrared images at the sub-AU spatial scale. Methods. We spatially resolve the circumstellar material and reconstruct images in the H and K bands using the MiRA algorithm. In addition, we interpret the interferometric observations using models that assume that the near-infrared excess is dominated by the emission of a circumstellar disk. We compare the images reconstructed from the VLTI measurements to images obtained using simulated model data.Results. The K-band image reveals three main elements: a ring-like feature located at ∼0.65 AU, a low surface brightness region inside 0.65 AU, and a central spot. At the maximum angular resolution of our observations (B/λ ∼ 1.3 mas), the ring is resolved while the central spot is only marginally resolved, preventing us from revealing the exact morphology of the circumstellar environment. We suggest that the ring traces silicate condensation, i.e., an opacity change, in a circumstellar disk around HR 5999. We build a model that includes a ring at the silicate sublimation radius and an inner disk of low surface brightness responsible for a large amount of the near-infrared continuum emission. The model successfully fits the SED, visibilities, and closure phases in the H and K bands, and provides evidence of a low surface brightness region inside the silicate sublimation radius. Conclusions. This study provides milli-arcsecond resolution images of the environment of HR 5999 and additional evidence that in Herbig Ae stars, there is material in a low surface brightness region, probably a low optical depth region, located inside the silicate sublimation radius and of unknown nature. The possibility that the formation of such a region in a thick disk is related to disk evolution should be investigated.

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“…On the other hand, at L , the source looks quite symmetrical. We note that maximumentropy (MEM) images usually have a super-resolution beyond the diffraction limit, since the reconstruction depends only on the entropy statistics (for a more detailed description, see Monnier 2003;Monnier & Allen 2013). Images presented in Fig.…”

Section: The Core Of Irs 9a Probed By K and L-band Sam Datamentioning

confidence: 99%

Unveiling the near-infrared structure of the massive-young stellar object NGC 3603 IRS 9A* with sparse aperture masking and spectroastrometry

Sánchez-Bermúdez

Hummel

Tuthill

et al. 2016

A&A

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Context. Contemporary theory holds that massive stars gather mass during their initial phases via accreting disk-like structures. However, conclusive evidence for disks has remained elusive for most massive young objects. This is mainly due to significant observational challenges: objects are rare and located at great distances within dusty, highly opaque environments. Incisive studies, even targeting individual objects, are therefore relevant to the progression of the field. NGC 3603 IRS 9A* is a young massive stellar object that is still surrounded by an envelope of molecular gas for which previous mid-infrared observations with long-baseline interferometry have provided evidence of a plausible disk of 50 mas diameter at its core. Aims. This work aims at a comprehensive study of the physics and morphology of IRS 9A at near-infrared wavelengths. Methods. New sparse aperture-masking interferometry data, taken with the near-infrared camera NACO of the Very Large Telescope (VLT) at K s and L wavelengths, were analyzed together with archival high-resolution H 2 and Brγ lines obtained with the cryogenic high-resolution infrared schelle spectrograph (CRIRES). Results. The trends in the calibrated visibilities at K s and L -bands suggest the presence of a partially resolved compact object with an angular size of ≤30 mas at the core of IRS 9A, together with the presence of over-resolved flux. The spectroastrometric signal of the H 2 line, obtained from the CRIRES spectra, shows that this spectral feature proceeds from the large-scale extended emission (∼300 mas), while the Brγ line appears to be formed at the core of the object (∼20 mas). To better understand the physics that drive IRS 9A, we have performed continuum radiative transfer modeling. Our best model supports the existence of a compact disk with an angular diameter of 20 mas, together with an outer envelope of 1 exhibiting a polar cavity with an opening angle of ∼30 • . This model reproduces the MIR morphology that has previously been derived in the literature and also matches the spectral energy distribution (SED) of the source. Conclusions. Our observations and modeling of IRS 9A support the presence of a disk at the core, surrounded by an envelope. This scenario is consistent with the brightness distribution (SED) of the source for near-and mid-infrared wavelengths at various spatial scales. However, our model suffers from remaining inconsistencies between SED modelling and the interferometric data. Moreover, the Brγ spectroastrometric signal indicates that the core of IRS 9A exhibits some form of complexity such as asymmetries in the disk. Future high-resolution observations are required to confirm the disk/envelope model and to flesh out the details of the physical form of the inner regions of IRS 9A.

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Optical interferometry in astronomy

Cited by 288 publications

References 240 publications

Interferometric observations of rapidly rotating stars

Interferometric observations of rapidly rotating stars

A low optical depth region in the inner disk of the Herbig Ae star HR 5999

Unveiling the near-infrared structure of the massive-young stellar object NGC 3603 IRS 9A* with sparse aperture masking and spectroastrometry

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