Exoplanet atmospheres

Abstract:

The SINFONI integral field spectrometer for the VLT will provide near-infrared spatially resolved spectra at spatial resolutions close to the diffraction limit of the telescope (0." 05 at 2 pm). 1024 spectra can be simultaneously obtained, covering a 32x32 pixel field of view with similar to 100% filling factor. The spectral resolution is R similar to 4500, corresponding to a kinematic resolution of 67 km s(-1). SINFONI is ideally suited to study stellar kinematics in the nuclear regions of normal spiral galaxies, using the near-infrared H and K band CO stellar absorption features. Integral field data from SINFONI will provide high-resolution two-dimensional maps of nuclear velocity dispersion and rotation, which in turn will constrain the anisotropy parameter and yield robust estimates of the central dark mass.

Abstract:

We report on the discovery of a double nucleus in M 83, based on measurements of the line of sight velocity distribution of stars observed at near infrared wavelengths with the VLT ISAAC spectrograph. We observe two peaks separated by 2.7" in the velocity dispersion profile of light from late-type stars measured along a slit 0.6" wide, centered on the peak of K band emission and with P.A. 51.7 degrees. The first peak coincides with the peak of the K band light distribution, widely assumed to be the galaxy nucleus. The second peak, of almost equal strength, almost coincides with the center of symmetry of the outer isophotes of the galaxy. The secondary peak location has little K band emission, and appears to be significantly extincted, even at near infrared wavelengths. It also lies along a mid-infrared bar, previously identified by Gallais et al. (1991) and shows strong hydrogen recombination emission at 1.875 microns. If we interpret the observed stellar velocity dispersion as coming from a virialized system, the two nuclei would each contain an enclosed mass of 13.2 x 10^6 M_sun within a radius of 5.4pc. These could either be massive star clusters, or supermassive dark objects.