Benjamin M. Zuckerman

The infrared spectrum of G29 - 38

De nouvelles donnees IR a bande large et etroite sont presentees pour la naine blanche G 29-38 qui montre un exces IR important. Laspect le plus caracteristique des nouvelles donnees est une emission intense a 10 μm qui soutient lexistence de matiere en orbite autour de G 29-38. On montre que cette matiere ne peut pas reposer dans un plan unique ou un disque epais, mais elle pourrait prendre la forme dun disque mince distordu

Infrared spectroscopy, imaging, and 10 micron photometry of Giclas 29-38

An NIR spectrum and several images of Giclas 29-38, a white dwarf suspected to have a brown dwarf in orbit around it, are presented. There is no absorption feature in the spectrum that is deeper than 5 percent in the wavelength range 1.95-2.45 microns, from which it is inferred that there is no feature deeper than 10 percent at 2.4 microns from any brown dwarf companion. The IR spectrum does not yield any strong constraint on whether or not the thermal emission observed from G29-38 comes from a brown dwarf or dust. The 1.6- and 2.2-micron images of G29-38 appear indistinguishable from a point source with an upper limit of 0.4 arcsec for the separation of the white dwarf and the source of the excess IR emission. This corresponds to a projected linear separation of 5.6 AU. A 2sigma limit at 10 microns of 10 mJy constrains possible alternative models for the IR excess by emission from dust grains. While the present results do not show evidence for the suspected brown dwarf companion around G29-38, the presence of such an object cannot be ruled out.

High-contrast imaging with Keck adaptive optics and OSIRIS

While more than 200 extrasolar planets have been discovered using indirect techniques, the direct detection of this class of object has remained at the sensitivity limits of ground based observatories. The development of improved adaptive optics systems and high contrast instruments has increased the sensitivity to extrasolar planets. We present high contrast results from the OSIRIS infrared lenslet-based integral field spectrograph (IFS) operating behind the Keck II adaptive optics (AO) system. OSIRIS spatially samples the Keck PSF at the diffraction limit, while providing a spectral resolution of 3800 for each spaxel. The OSIRIS integral field sampling simultaneously monitors the PSF over a broad band (20%), and this sampling is used to identify and suppress speckle diffraction features. The high-contrast sensitivity of Keck II AO near-infrared IFS (OSIRIS) and near-infrared imager (NIRC2) are compared.