In the Spirit of Lyot 2010

Update on Fomalhaut b

Paul KALAS — 2011-05-11T12:39:54Z

Submitted by Paul KALAS

Authors

P. Kalas (1), J. Graham(1), M. Fitzgerald(2), M. Clampin(3)

Affiliations

(1) UC Berkley; (2) UCLA; (3) NASA GSFC, USA;

Abstract

Exoplanetary systems with SAFARI

Anthony BOCCALETTI — 2011-05-11T12:36:11Z

Submitted by P. ROELFSEMA

Authors

P. Roelfsema, B. Swinyard, J. Goicoechea

Affiliations

SRON; Rutherford Appleton Laboratory; CAB-CSIC/INTA

Abstract

A simple and efficient model for polychromatic focal plane wave-front sensor

Sarah DANDY — 2010-10-05T08:58:15Z

submitted by Sarah Dandy

Authors

S. Dandy, J.-F. Sauvage, T. Fusco, and L. Mugnier

Affiliations

ONERA

Abstract

Phase Diversity is a focal-plane technique which is chromatic by nature. The use of a monochromatic model on wide-band imaging results of an additional error function of the spectral range.We present here a second order modeling of the focal plane wave-front sensing error due to wide-band imaging and propose a first order correction by inverse problem using an iterative correction. Simulation and experimental results on the ONERA AO bench are presented. A nanometric accuracy is demonstrated for spectral band larger than a few hundreds micrometers.

Parallelization of exoplanets detection algorithms based on field rotation; example of the MOODS algorithm for SPHERE.

Damien MATTEI — 2010-09-23T18:58:10Z

Submitted by D. Mattei

Authors

D. Mattei, I. Smith, A. Ferrari, M. Carbillet

Affiliations

UMR 6525 H. Fizeau (UNS/CNRS/OCA)

Abstract

Post-processing for exoplanet detection using direct imaging requires large data cubes and/or sophisticated signal processing technics. For alt-azimuthal mounts, a projection effect called field rotation makes the potential planet rotate in a known manner on the set of images. For ground based telescopes that use extreme adaptive optics and advanced coronagraphy, technics based on field rotation are already broadly used and still under progress.

In most such technics, for a given initial position of the planet the planet intensity estimate is a linear function of the set of images. However, due to field rotation the modified instrumental response applied is not shift invariant like usual linear filters. Testing all possible initial positions is therefore very time-consuming. To reduce the time process, we propose to deal with each subset of initial positions computed on a different machine using parallelization programming.

In particular, the MOODS algorithm dedicated to the VLT-SPHERE instrument, that estimates jointly the light contributions of the star and the potential exoplanet, is parallelized on the Observatoire de la Côte d'Azur cluster. Different parallelization methods (OpenMP, MPI, Jobs Array) have been elaborated for the initial MOODS code and compared to each other. The one finally chosen splits the initial positions on the processors available by accounting at best for the different constraints of the cluster structure: memory, job submission queues, number of available CPUs, cluster average load.

At the end, a standard set of images is satisfactorily processed in a few hours instead of a few days.

The Ages of Stars Hosting Substellar Companions

Eric MAMAJEK — 2010-09-15T05:44:54Z

submitted by Eric Mamajek

Authors

Eric Mamajek

Affiliations

University of Rochester

Abstract

Accurate stellar ages are a critical parameter in characterizing substellar companions and in planning imaging surveys to find new benchmark systems. I'll review recent results on the estimation of the ages of stars hosting substellar companions, with particular emphasis on HR 8799, Fomalhaut, and GJ 758. One new result is that Fomalhaut is likely to be older than previously claimed. A modern isochronal analysis for Fomalhaut yields an age of 320 Myr. From revised Hipparcos astrometry and published radial velocities, it appears that Fomalhaut and TW PsA have a 3D separation of only 58000+-3000 AU and have statistically consistent 3D velocities differing by only 0.6+-0.5 km/s. Hence, Fomalhaut and TW PsA appear to constitute a wide physical binary, and I adopt the gyrochronology age for TW PsA (410 Myr) as another independent age estimate for Fomalhaut. Combining these new estimates yields a consensus age for Fomalhaut of 360+-50 Myr, which is nearly a factor of two older than previous estimates (200+-100 Myr). The preponderance of age-related evidence seems to suggest that HR 8799 is young ( 0.1 Gyr), and that GJ 758 is old ( 7 Gyr) and the mass of its companion is well above the D-burning limit ( 35 Jupiter masses). I'll also discuss results from an upcoming study on ages derived from chromospheric activity for solar-type dwarf exoplanet hosts (Slipski & Mamajek, submitted to ApJ) which support the use of activity-derived ages even for stars older than 1 Gyr (albeit with sizeable uncertainties).

Direct Detections of the HR8799 planets using the LOCI algorithm on NICMOS data

James HAGAN — 2010-09-15T05:41:32Z

submitted by James Hagan

Authors

James Hagan, Adrien Thormann, Rémi Soummer, Laurent Pueyo, Christian Marois

Affiliations

STScI

Abstract

In 1998, the star HR8799 was observed using the coronographic camera NIC2 in a survey to search for massive Jupiters around young, nearby, main sequence stars. In 2009, more than a decade later, Lafrenière et al. revisited this data. Along with some prior knowledge of the HR8799 exoplanetary system, they developed and utilized an advanced algorithm for PSF subtraction called the LOCI (locally optimized combination of images) algorithm and detected the exoplanet HR8799 b. We revisit the same data and systematically optimize LOCI parameters. We present the direct detections of HR8799 b, c, and a possible detection of d in the same NICMOS data, and we study the effects the LOCI parameters have on the measured astrometry and photometry of each planet.

Single Aperture Imaging Astrometry with a Diffracting Pupil: Laboratory demonstration

Eduardo BENDEK — 2010-09-13T10:33:20Z

submitted by Eduardo Bendek

Authors

Eduardo Bendek, Mark Ammons, Thomas Milster, Olivier Guyon

Affiliations

University of Arizona

Abstract

A laboratory is being set up at university of Arizona to serve as proof of concept of a novel technique to overcome the astrometric errors caused by optical distortions on imaging telescopes. This new technique enables sub microarcsecond astrometry with medium-size (<2-m) space telescopes, and can be used simultaneously with coronagraphy for exhaustive characterization of exoplanets (mass, spectra, orbit). The technique uses an array of 10 μm dots over the primary mirror causing diffraction spikes on the image due the polychromatic nature of the source. The spikes are used as reference for the astrometry measurements and encode any aberration of the optical system. The laboratory aims to achieve 10 μas, simulating 0.14 uas precision on a 1.4 m telescope. Prototype mirrors with the small diffractive dots have been manufactured by lithography. We describe the laboratory test design and data analysis. We also show early results obtained with the diffractive mirror, showing the diffraction spikes which calibrate distortions in the optical system. Technical challenges to apply this technique to a full size optical system with an aspheric primary mirror are discussed.

The Program

Anthony BOCCALETTI — 2010-09-03T08:41:52Z

Program update as on October 22nd, 2010

Updated on Oct. 22nd

Due to a large attendance the contributed talks have been reduced to 15' (including questions) instead of the 20' initially proposed.

The program features :

11 review talks
71 contributed talks
75 posters

The program and list of posters are available for download in pdf files. Individual abstracts are consultable here session by session.


Program of talks (22oct)


Program of posters (22oct)

Calibration constraints for high contrast imaging

Maud LANGLOIS — 2010-09-02T15:11:24Z

Submitted by M. Langlois

Authors

M. Langlois, A. Vigan, K Dohlen et al.

Affiliations

CNRS, LAM/CNRS

Abstract

The detection and characterization of extrasolar planets by direct imaging is becoming more and more promising with the preparation of dedicated high-contrast instruments and the help of new data analysis techniques. This paper describes the instrument performances and the impact of instrumental calibrations on finding and characterizing extrasolar planets, and on observing strategies for IRDIS, one of the SPHERE subsystems,. We discuss the main instrumental calibration challenges to be addressed to reach very high contrast imaging with future instruments such as SPHERE and in the future for ELT instruments, where added instrumental complexity will increase the calibration time and accuracy.

Conférence Grand Public

Anthony BOCCALETTI — 2010-09-01T08:44:54Z

version française

Conférence grand public présentée par l'Observatoire de Paris

le 26 Octobre 2010 à 19h
à l'Université Paris Diderot, amphithéâtre Buffon
15 rue Hélène Brion, 75013 Paris

"Premières lumières de nouveaux mondes : imagerie et spectroscopie de planètes extra-solaires"

par :

Anne-Marie Lagrange (Laboratoire d'Astrophysique de l'Observatoire de Grenoble / CNRS)

et :

Giovanna Tinetti (University College London)

Dans le cadre d'un colloque scientifique international, l'Observatoire de Paris propose une conférence grand public sur le thème des exoplanètes. Les deux oratrices présenteront les résultats récents de deux techniques particulières et les futurs projets qui devraient nous permettre d'améliorer notre connaissance sur ces nouvelles planètes.

Entrée gratuite dans la limite des places disponibles. Durée : 2h
Renseignements sur www.grandpublic.obspm.fr