Coupling MOAO with Integral Field Spectroscopy: specifications for the VLT and the E-ELT

[Abridged] We have developed an end-to-end simulation to specify the science requirements of a MOAO-fed integral field spectrograph on either an 8m or 42m telescope. Our simulations re-scales observations of local galaxies or results from numerical simulations of disk or interacting galaxies. For the current analysis, we limit ourselves to a local disk galaxy which exhibits simple rotation and a simulation of a merger. We have attempted to generalize our results by introducing the simple concepts of "PSF contrast" which is the amount of light polluting adjacent spectra which we find drives the smallest EE at a given spatial scale. The choice of the spatial sampling is driven by the "scale-coupling", i.e., the relationship between the IFU pixel scale and the size of the features that need to be recovered by 3D spectroscopy in order to understand the nature of the galaxy and its substructure. Because the dynamical nature of galaxies are mostly reflected in their large-scale motions, a relatively coarse spatial resolution is enough to distinguish between a rotating disk and a major merger. Although we used a limited number of morpho-kinematic cases, our simulations suggest that, on a 42m telescope, the choice of an IFU pixel scale of 50-75 mas seems to be sufficient. Such a coarse sampling has the benefit of lowering the exposure time to reach a specific signal-to-noise as well as relaxing the performance of the MOAO system. On the other hand, recovering the full 2D-kinematics of z~4 galaxies requires high signal-to-noise and at least an EE of 34% in 150 mas (2 pixels of 75 mas). Finally, we carried out a similar study at z=1.6 with a MOAO-fed spectrograph for an 8m, and find that at least an EE of 30% at 0.25 arcsec spatial sampling is required to understand the nature of disks and mergers.Comment: 17 pages, 20 figures, accepted for publication in the MNRA

A search for circumstellar dust disks with ADONIS

We present results of a coronographic imaging search for circumstellar dust disks with the Adaptive Optics Near Infrared System (ADONIS) at the ESO 3.6m telescope in La Silla (Chile). 22 candidate stars, known to be orbited by a planet or to show infrared excess radiation, were examined for circumstellar material. In the PSF-subtracted images no clear disk was found. We further determine the detection sensitivities and outline how remaining atmospheric fluctuations still can hamper adaptive optics observations.Comment: To appear in A&A, in pres

High-contrast Imaging Study on the Candidate Companions Around the Star AH Lep

AH Lep (R.A._(J2000) = 05 34 09.16, decl._(J2000) = −15 17 03.18) is a young, nearby, solar-type star (G2V). Gaia DR2 and BANYAN Sigma provide a 99.9% probability of the star belonging to the Columba moving group (Zuckerman et al. 2011), yielding an estimated age of 42^(+6)_(-4) Myr (Bell et al. 2015). It has a parallax of p = 17.26 mas, corresponding to a distance of d = 57.9 pc (Gaia Collaboration et al. 2018). The star has been reported to have variable photospheric and X-ray emission (e.g., Burleigh et al. 1998; Cutispoto et al. 2003)

Vision Suisse de la Bretagne chez Cambry.

ISBN : 978-2-901737-80-3 ; 231 p.International audienceUne vingtaine de fois dans son fameux Voyage, Cambry rapproche les paysages du Finistère de ceux de la Suisse. Dans la plupart des cas, ces comparaisons tournent à l'avantage de son département breton. Une telle fréquence, renforcée par une certaine constance de l'interprétation, ne sautait être fortuite. Aussi conviendra-t-il, après avoir examiné ces références, de trouver une signification qui pourrait faire de Cambry, le premier révélateur d'une Bretagne élue d'un celtisme en quête d'identité topographique

Orbital Dynamics of Multi-Planet Systems with Eccentricity Diversity

Since exoplanets were detected using the radial velocity method, they have revealed a diverse distribution of orbital configurations. Amongst these are planets in highly eccentric orbits (e > 0.5). Most of these systems consist of a single planet but several have been found to also contain a longer period planet in a near-circular orbit. Here we use the latest Keplerian orbital solutions to investigate four known systems which exhibit this extreme eccentricity diversity; HD 37605, HD 74156, HD 163607, and HD 168443. We place limits on the presence of additional planets in these systems based on the radial velocity residuals. We show that the two known planets in each system exchange angular momentum through secular oscillations of their eccentricities. We calculate the amplitude and timescale for these eccentricity oscillations and associated periastron precession. We further demonstrate the effect of mutual orbital inclinations on the amplitude of high-frequency eccentricity oscillations. Finally, we discuss the implications of these oscillations in the context of possible origin scenarios for unequal eccentricities.Comment: 12 pages, 9 figures, accepted for publication in the Astrophysical Journa

Laboratory comparison of coronagraphic concepts under dynamical seeing and high-order adaptive optics correction

The exoplanetary science through direct imaging and spectroscopy will largely expand with the forthcoming development of new instruments at the VLT (SPHERE), Gemini (GPI), Subaru (HiCIAO), and Palomar (Project 1640) observatories. All these ground-based adaptive optics instruments combine extremely high performance adaptive optics (XAO) systems correcting for the atmospheric turbulence with advanced starlight-cancellation techniques such as coronagraphy to deliver contrast ratios of about 10-6 to 10-7. While the past fifteen years have seen intensive research and the development of high-contrast coronagraph concepts, very few concepts have been tested under dynamical seeing conditions (either during sky observation or in a realistic laboratory environment). In this paper, we discuss the results obtained with four different coronagraphs -- phase and amplitude types -- on the High-Order Testbench (HOT), the adaptive optics facility developed at ESO. This facility emphasizes realistic conditions encountered at a telescope (e.g., VLT), including a turbulence generator and a high-order adaptive optics system. It enables to evaluate the performance of high-contrast coronagraphs in the near-IR operating with an AO-corrected PSF of 90% Strehl ratio under 0.5 arcsec dynamical seeing.Comment: Accepted for publication in MNRA

CASE REPORT - Reactivated toxoplasmosis presenting with non-tender hepatomegaly in a patient with HIV infection

No Abstract African Journal of Health Sciences Vol. 14 (1-2) 2007: pp. 97-9

On the Origin of the Eccentricities of Extrasolar Planets

We develop a phenomenological theory that aims to account for the origin of the large eccentricities of extrasolar planets and that of the small eccentricities in the solar system, the preference for apsidal alignment in non-resonant multiplanet systems, and the origin of the similarities in the eccentricity distribution of extra-solar planets and that of spectroscopic binary stars. We show that if a physical process is weakly dependent on the local dynamics of the companion and imparts a small relative acceleration to the star-companion system, the eccentricity of the companion's orbit is excited to large values depending on the direction and duration of acceleration. A natural candidate for such processes are asymmetric stellar jets and star-disk winds. When the acceleration originates from a precessing jet, large eccentricities can be excited by the resonance of the jet's precession frequency with the induced acceleration's excitation frequency even for nearly perpendicular jets. Precession also reduces the eccentricity amplitude far inside the resonance radius. The acceleration's strength is best constrained in multiplanet systems because of the companions' mutual gravitational perturbations, while the acceleration's duration is bounded by the condition that the residual velocity imparted to the star is smaller than the stellar velocity dispersion in the Galaxy. In the outer parts of the star-companion system where the acceleration excitation time is comparable to or smaller than the orbital period, significant radial migration takes place which may have important consequences for the dynamics of the minor body populations in the solar system. The theory is illustrated with the $\upsilon$ Andromedae binary system.Comment: 41 pages, 14 figures, accepted for publication in the Astronomical Journa

Telescope interferometers: an alternative to classical wavefront sensors

Several types of Wavefront Sensors (WFS) are nowadays available in the field of Adaptive Optics (AO). Generally speaking, their basic principle consists in measuring slopes or curvatures of Wavefront Errors (WFE) transmitted by a telescope, subsequently reconstructing WFEs digitally. Such process, however, does not seem to be well suited for evaluating co-phasing or piston errors of future large segmented telescopes in quasi real-time. This communication presents an original, recently proposed technique for direct WFE sensing. The principle of the device, which is named "Telescope-Interferometer" (TI), is based on the addition of a reference optical arm into the telescope pupil plane. Then incident WFEs are deduced from Point Spread Function (PSF) measurements at the telescope focal plane. Herein are described two different types of TIs, and their performance are discussed in terms of intrinsic measurement accuracy and spatial resolution. Various error sources are studied by means of numerical simulations, among which photon noise sounds the most critical. Those computations finally help to define the application range of the TI method in an AO regime, including main and auxiliary telescope diameters and magnitude of the guide star. Some practical examples of optical configurations are also described and commented.Comment: 12 pages, 10 figure