Exoplanets and Stellar Physics

Abstract:

Progress in understanding the embedded stars in LkHa225 has been hampered by their variability, making it hard to compare data taken at different times, and by the limited resolution of the available data, which cannot probe the small scales between the two stars. In an attempt to overcome these difficulties, we present new near-infrared data on this object taken using the ALFA adaptive optics system with the MPE 3D integral field spectrometer and the near-infrared camera Omega-Cass. The stars themselves have K-band spectra which are dominated by warm dust emission, analagous to class I-II for low mass YSOs, suggesting that the stars are in a phase where they are still accreting matter. On the other hand, the ridge of continuum emission between them is rather bluer, suggestive of extincted and/or scattered stellar light rather than direct dust emission. The compactness of the CO emission seen toward each star argues for accretion disks (which can also account for much of the K-band veiling) rather than a neutral wind. In contrast to other YSOs with CO emission, LkHa225 has no detectable Br_gamma emission. Additionally there is no H_2 detected on the northern star, although we do confirm that the strongest H_2 emission is on the southern star, where we find it is excited primarily by thermal mechanisms. A second knot of H_2 is observed to its northeast, with a velocity shift of -75kms and a higher fraction of non-thermal emission. This is discussed with reference to the H2O maser, the molecular outflow, and [S II] emission observed between the stars.

Abstract:

We report new results on the stellar kinematics and the mass distribution of the galaxy NGC 3115 based on NIR integral field spectroscopic data. Investigations using long slit spectroscopic data have yielded strong evidence for the presence of a massive dark object of ca. 10(9) solar masses. NGC 3115 therefore appears to be a prominent candidate for hosting a black hole in its center. We demonstrate that with integral field spectroscopy the rotation and velocity dispersion can be much better constrained by sampling in both spatial dimensions. This yields revised and more secure results.

Abstract:

We present results from sub-arcsecond near infrared integral field spectroscopy and millimeter IRAM-interferometry of the interacting galaxy NGC 6240. Using stellar absorption features in the NIR we determined the stellar velocity field and dispersion in NGC 6240. The two NIR emission peaks show rapid rotation and indicate a prograde encounter of the two progenitor galaxies. From the velocity dispersion an excess mass between the two nuclei is detected. This mass can be attributed to a massive rotating disk of cold CO gas located between the nuclei.