E. Pedretti

Rutherford Appleton Laboratory

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N. Thureau

University of St Andrews

John D. Monnier

University of Michigan–Ann Arbor

J. Sturmann

Georgia State University

Theo A. ten Brummelaar

Georgia State University

Jean-Philippe Berger

Centre National de la Recherche Scientifique

Harold A. McAlister

Georgia State University

R. Millan‐Gabet

Center for Astrophysics Harvard & Smithsonian

L. Sturmann

Georgia State University

N. Turner

Jet Propulsion Laboratory

Michael Ireland

Australian National University

Cooperative Institutions

Georgia State University

Mount Wilson Observatory

California Institute of Technology

University of Michigan–Ann Arbor

University of Cambridge

Michigan United

Laboratoire d’études spatiales et d’instrumentation en astrophysique

Chart Industries (United States)

Astronomy and Space

Center for Astrophysics Harvard & Smithsonian

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Infrared images of the transiting disk in the ε Aurigae system

Nature (2010)

Brian Kloppenborg R. E. Stencel John D. Monnier Gail Schaefer M. Zhao

Opacity

Symbol (formal)

Star (game theory)

Eclipse

10.1038/nature08968

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Citations (134)

Imaging Disk Distortion Of Be Binary System δ Scorpii Near Periastron

American Astronomical Society Meeting Abstracts #219 (2012)

X. Che John D. Monnier Fabien Baron Stefan Kraus E. Pedretti

Distortion (music)

Source

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The Interferometric Orbit and Fundamental Parameters for Spica from the CHARA and SUSI Arrays

HAL (Le Centre pour la Communication Scientifique Directe) (2009)

J. P. Aufdenberg Michael Ireland A. Mérand John D. Monnier M. Zhao

Spica

Orbit (dynamics)

Source

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Imaging with the CHARA interferometer

New Astronomy Reviews (2009)

E. Pedretti John D. Monnier Theo A. ten Brummelaar N. Thureau

Chara

10.1016/j.newar.2010.07.008

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Citations (17)

Imaging the asymmetric dust shell around CI Cam with long baseline optical interferometry

Monthly Notices of the Royal Astronomical Society (2009)

N. Thureau John D. Monnier W. A. Traub R. Millan‐Gabet E. Pedretti

We present the first high angular resolution observation of the B[e] star/X-ray transient object CI Cam, performed with the two-telescope Infrared Optical Telescope Array (IOTA), its upgraded three-telescope version (IOTA3T) and the Palomar Testbed Interferometer (PTI). Visibilities and closure phases were obtained using the IONIC-3 integrated optics beam combiner. CI Cam was observed in the near-infrared H and K spectral bands, wavelengths well suited to measure the size and study the geometry of the hot dust surrounding CI Cam. The analysis of the visibility data over an 8 year period from soon after the 1998 outburst to 2006 shows that the dust visibility has not changed over the years. The visibility data shows that CI Cam is elongated which confirms the disc-shape of the circumstellar environment and totally rules out the hypothesis of a spherical dust shell. Closure phase measurements show direct evidence of asymmetries in the circumstellar environment of CI Cam and we conclude that the dust surrounding CI Cam lies in an inhomogeneous disc seen at an angle. The near-infrared dust emission appears as an elliptical skewed Gaussian ring with a major axis a = 7.58 +/- 0.24 mas, an axis ratio r = 0.39 +/- 0.03 and a position angle theta = 35 +/- 2 deg.

Circumstellar dust

Visibility

Position angle

Very Large Telescope

10.1111/j.1365-2966.2009.14949.x

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Citations (14)

Detection of non-radial pulsation and faint companion in the symbiotic star CH Cyg

Monthly Notices of the Royal Astronomical Society (2009)

E. Pedretti John D. Monnier S. Lacour W. A. Traub W. C. Danchi

We have detected asymmetry in the symbiotic star CH Cyg through the measurement of precision closure-phase with the IONIC beam combiner, at the IOTA interferometer. The position of the asymmetry changes with time and is correlated with the phase of the 2.1-yr period found in the radial velocity measurements for this star. We can model the time-dependent asymmetry either as the orbit of a low-mass companion around the M giant or as an asymmetric, 20% change in brightness across the M giant. We do not detect a change in the size of the star during a 3 year monitoring period neither with respect to time nor with respect to wavelength. We find a spherical dust-shell with an emission size of 2.2+/-0.1 D* FWHM around the M giant star. The star to dust flux ratio is estimated to be 11.63+/-0.3. While the most likely explanation for the 20% change in brightness is non-radial pulsation we argue that a low-mass companion in close orbit could be the physical cause of the pulsation. The combined effect of pulsation and low-mass companion could explain the behaviour revealed by the radial-velocity curves and the time-dependent asymmetry detected in the closure-phase data. If CH Cyg is a typical long secondary period variable then these variations could be explained by the effect of an orbiting low-mass companion on the primary star.

Radial velocity

Orbit (dynamics)

Orbital period

10.1111/j.1365-2966.2009.14906.x

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Citations (8)

Imaging the Surface of Altair

Science (2007)

John D. Monnier Ming Zhao E. Pedretti N. Thureau Michael Ireland

Spatially resolving the surfaces of nearby stars promises to advance our knowledge of stellar physics. Using optical long-baseline interferometry, we constructed a near-infrared image of the rapidly rotating hot star Altair with a resolution of <1 milliarcsecond. The image clearly reveals the strong effect of gravity darkening on the highly distorted stellar photosphere. Standard models for a uniformly rotating star cannot explain our findings, which appear to result from differential rotation, alternative gravity-darkening laws, or both.

Photosphere

Surface gravity

Stellar rotation

Star (game theory)

Limb darkening

10.1126/science.1143205

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Citations (325)

Imaging the surface of Altair and a MIRC update

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2008)

John D. Monnier Ming Zhao E. Pedretti N. Thureau Michael Ireland

We report the first scientific results from the Michigan Infrared Combiner (MIRC), including the first resolved image of a main-sequence star besides the Sun. Using the CHARA Array, MIRC was able to clearly resolve the well-known elongation of Altair's photosphere due to centrifugal distortion, and was also able to unambiguously image the effect of gravity darkening. In this report, we also show preliminary images of the interacting binary β Lyr and give an update of MIRC performance.

10.1117/12.789754

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Citations (7)