Near-infrared mapping of spiral barred galaxies

In external galaxies, near-infrared emission originates from stellar populations, hot dust, free-free emission from H+ regions, gaseous emission, non-thermal nucleus if any. Because of the low extinction compared to the visible, infrared wavelengths are useful to probe regions obscured by dust such as central parts where starburst phenomena can occur because of the large quantity of matter. The results presented were obtained with a 32 x 32 InSb charge injection device (CID) array cooled at 4K, at the f/36 cassegrain focus of the 3m60 Canada-France-Hawaii telescope with a spatial resolution of 0.5 inches per pixel. The objects presented are spiral barred galaxies mapped at J(1.25 microns), H(1.65 microns) and K(2.2 microns). The non-axisymetric potential due to the presence of a bar induces dynamical processes leading to the confinement of matter and peculiar morphologies. Infrared imaging is used to study the link between various components. Correlations with other wavelengths ranges and 2-colors diagrams ((J-H), (H-K)) lead to the identification of star forming regions, nucleus. Maps show structures connected to the central core. The question is, are they flowing away or toward the nucleus. Observations of M83 lead to several conclusions. The star forming region, detected in the visible and the infrared cannot be very compact and must extend to the edge of the matter concentration. The general shape of the near-infrared emission and the location of radio and 10 micron peaks suggest the confinement of matter between the inner Linblad resonances localized from CO measurements about 100 and 400 pc. The distribution of color indices in the arc from southern part to the star forming region suggests an increasing amount of gas and a time evolution eventually triggered by supernova explosions. Close to the direction of the bar, a bridge-like structure connects the arc to the nucleus with peculiar color indices. Perhaps, this structure can be linked to a height velocity component seen in UV and we can attribute it to a jet and/or a matter flow along the bar toward the nucleus, fuelling it. NGC 1068 is the nearest Seyfert 2 galaxy. It has been a subject of many studies at all wavelengths. This object was mapped at J, H, K, L and M, and in polaro-imagery. Results are given

Transdet: a matched-filter based algorithm for transit detection - application to simulated COROT light curves

We present a matched-filter based algorithm for transit detection and its application to simulated COROT light curves. This algorithm stems from the work by Bord\'e, Rouan & L\'eger (2003). We describe the different steps we intend to take to discriminate between planets and stellar companions using the three photometric bands provided by COROT. These steps include the search for secondary transits, the search for ellipsoidal variability, and the study of transit chromaticity. We also discuss the performance of this approach in the context of blind tests organized inside the COROT exoplanet consortium.Comment: 6 pages, 4 figures, in Transiting Extrasolar Planets Workshop, meeting held in Heidelberg, 25-28 September 200

Electric Dipole Radiation from Spinning Dust Grains

We discuss the rotational excitation of small interstellar grains and the resulting electric dipole radiation from spinning dust. Attention is given to excitation and damping of rotation by: collisions with neutrals; collisions with ions; plasma drag; emission of infrared radiation; emission of microwave radiation; photoelectric emission; and formation of H_2 on the grain surface. We introduce dimensionless functions F and G which allow direct comparison of the contributions of different mechanisms to rotational drag and excitation. Emissivities are estimated for dust in different phases of the interstellar medium, including diffuse HI, warm HI, low-density photoionized gas, and cold molecular gas. Spinning dust grains can explain much, and perhaps all, of the 14-50 GHz background component recently observed in CBR studies. It should be possible to detect rotational emission from small grains by ground-based observations of molecular clouds.Comment: 59 pages, 19 eps figures, uses aaspp4.sty . Submitted to Ap.

Flares and variability from Sagittarius A*: five nights of simultaneous multi-wavelength observations

Aims. We report on simultaneous observations and modeling of mid-infrared (MIR), near-infrared (NIR), and submillimeter (submm) emission of the source Sgr A* associated with the supermassive black hole at the center of our Galaxy. Our goal was to monitor the activity of Sgr A* at different wavelengths in order to constrain the emitting processes and gain insight into the nature of the close environment of Sgr A*. Methods. We used the MIR instrument VISIR in the BURST imaging mode, the adaptive optics assisted NIR camera NACO, and the sub-mm antenna APEX to monitor Sgr A* over several nights in July 2007. Results. The observations reveal remarkable variability in the NIR and sub-mm during the five nights of observation. No source was detected in the MIR, but we derived the lowest upper limit for a flare at 8.59 microns (22.4 mJy with A_8.59mu = 1.6+/- 0.5). This observational constraint makes us discard the observed NIR emission as coming from a thermal component emitting at sub-mm frequencies. Moreover, comparison of the sub-mm and NIR variability shows that the highest NIR fluxes (flares) are coincident with the lowest sub-mm levels of our five-night campaign involving three flares. We explain this behavior by a loss of electrons to the system and/or by a decrease in the magnetic field, as might conceivably occur in scenarios involving fast outflows and/or magnetic reconnection.Comment: 10 pages, 7 figures, published in A&

The FALCON concept: multi-object spectroscopy combined with MCAO in near-IR

A large fraction of the present-day stellar mass was formed between z=0.5 and z~3 and our understanding of the formation mechanisms at work at these epochs requires both high spatial and high spectral resolution: one shall simultaneously} obtain images of objects with typical sizes as small as 1-2kpc(~0''.1), while achieving 20-50 km/s (R >= 5000) spectral resolution. The obvious instrumental solution to adopt in order to tackle the science goal is therefore a combination of multi-object 3D spectrograph with multi-conjugate adaptive optics in large fields. A partial, but still competitive correction shall be prefered, over a much wider field of view. This can be done by estimating the turbulent volume from sets of natural guide stars, by optimizing the correction to several and discrete small areas of few arcsec2 selected in a large field (Nasmyth field of 25 arcmin) and by correcting up to the 6th, and eventually, up to the 60th Zernike modes. Simulations on real extragalactic fields, show that for most sources (>80%), the recovered resolution could reach 0".15-0".25 in the J and H bands. Detection of point-like objects is improved by factors from 3 to >10, when compared with an instrument without adaptive correction. The proposed instrument concept, FALCON, is equiped with deployable mini-integral field units (IFUs), achieving spectral resolutions between R=5000 and 20000. Its multiplex capability, combined with high spatial and spectral resolution characteristics, is a natural ground based complement to the next generation of space telescopes.Comment: ESO Workshop Proceedings: Scientific Drivers for ESO Future VLT/VLTI Instrumentation, 10 pages and 5 figure

A probable giant planet imaged in the Beta Pictoris disk

Since the discovery of its dusty disk in 1984, Beta Pictoris has become the prototype of young early-type planetary systems, and there are now various indications that a massive Jovian planet is orbiting the star at ~ 10 AU. However, no planets have been detected around this star so far. Our goal was to investigate the close environment of Beta Pic, searching for planetary companion(s). Deep adaptive-optics L'-band images of Beta Pic were recorded using the NaCo instrument at the Very Large Telescope. A faint point-like signal is detected at a projected distance of ~ 8 AU from the star, within the North-East side of the dust disk. Various tests were made to rule out with a good confidence level possible instrumental or atmospheric artifacts. The probability of a foreground or background contaminant is extremely low, based in addition on the analysis of previous deep Hubble Space Telescope images. The object L'=11.2 apparent magnitude would indicate a typical temperature of ~1500 K and a mass of ~ 8 Jovian masses. If confirmed, it could explain the main morphological and dynamical peculiarities of the Beta Pic system. The present detection is unique among A-stars by the proximity of the resolved planet to its parent star. Its closeness and location inside the Beta Pic disk suggest a formation process by core accretion or disk instabilities rather than a binary-like formation process.Comment: 5 pages, 3 figures, 1 table. A&A Letters, in pres

The near-infrared spectral energy distribution of {\beta} Pictoris b

A gas giant planet has previously been directly seen orbiting at 8-10 AU within the debris disk of the ~12 Myr old star {\beta} Pictoris. The {\beta} Pictoris system offers the rare opportunity to study the physical and atmospheric properties of an exoplanet placed on a wide orbit and to establish its formation scenario. We obtained J (1.265 {\mu}m), H (1.66 {\mu}m), and M' (4.78 {\mu}m) band angular differential imaging of the system between 2011 and 2012. We detect the planetary companion in our four-epoch observations. We estimate J = 14.0 +- 0.3, H = 13.5 +- 0.2, and M' = 11.0 +- 0.3 mag. Our new astrometry consolidates previous semi-major axis (sma=8-10 AU) and excentricity (e <= 0.15) estimates of the planet. These constraints, and those derived from radial velocities of the star provides independent upper limits on the mass of {\beta} Pictoris b of 12 and 15.5 MJup for semi-major axis of 9 and 10 AU. The location of {\beta} Pictoris b in color-magnitude diagrams suggests it has spectroscopic properties similar to L0-L4 dwarfs. This enables to derive Log10(L/Lsun) = -3.87 +- 0.08 for the companion. The analysis with 7 PHOENIX-based atmospheric models reveals the planet has a dusty atmosphere with Teff = 1700 +- 100 K and log g = 4.0+- 0.5. "Hot-start" evolutionary models give a new mass of 10+3-2 MJup from Teff and 9+3-2 MJup from luminosity. Predictions of "cold-start" models are inconsistent with independent constraints on the planet mass. "Warm-start" models constrain the mass to M >= 6MJup and the initial entropies to values (Sinit >= 9.3Kb/baryon), intermediate between those considered for cold/hot-start models, but likely closer to those of hot-start models.Comment: 19 pages, accepted in Astronomy and Astrophysic

Pharmacokinetics and dosage adjustment of cefotiam in renal impaired patients

The pharmacokinetics of cefotiam were investigated after intravenous administration of 1 g to 2 healthy volunteers with normal renal function and to 16 patients whose creatinine clearance ranged from 4.7 to 0.11/h (78 to 1.66 ml/min). The elimination half-life varied from 1.1 h in normal subjects to 13 h in patients and the total plasma clearance from 21 to 0.6 1/h (350 to 10 ml/min). The urinary recovery decreased from 62% of the dose in normal subjects to 1.1% in patients, and the renal clearance from 15 to 0.03 l/h (250 to 0.5 ml/min). Plasma and renal clearances of cefotiam correlated well with the creatinine clearance. The dosage schedule for cefotiam in patients with normal renal function can be used in the presence of renal failure when the creatinine clearance is equal to or greater than 1 1/h (16.6 ml/min). For patients whose creatinine clearance is less than 1 1/h, the dose must be decreased to 75% of that for a patient with normal renal function only when it is given every 6 or 8

On-sky observations with an achromatic hybrid phase knife coronagraph in the visible

CONTEXT: The four-quadrant phase mask stellar coronagraph, introduced by D. Rouan et al., is capable of achieving very high dynamical range imaging and was studied in the context of the direct detection of extra-solar planets. Achromatic four-quadrant phase mask is currently being developed for broadband IR applications. AIMS: We report on laboratory and on-sky tests of a prototype coronagraph in the visible. This prototype, the achromatic hybrid phase knife coronagraph, was derived from the four-quadrant phase mask principle. METHODS: The instrumental setup implementing the coronagraph itself was designed to record the pre- and post-coronagraphic images simultaneously so that an efficient real-time image selection procedure can be performed. We describe the coronagraph and the associated tools that enable robust and repeatable observations. We present an algorithm of image selection that has been tested against the real on-sky data of the binary star HD80081 (* 38 Lyn). RESULTS Although the observing conditions were poor, the efficiency of the proposed method is proven. From this experiment, we derive procedures that can apply to future focal instruments associating adaptive optics and coronagraphy, targeting high dynamic range imaging in astronomy, such as detecting extra-solar planets