%0 Generic %A CARMONA GONZALEZ, Andres %D 2007 %F heidok:7663 %K Astronomy , Protoplanetary Disks , Infrared Astronomy , Pre-Main Sequence Stars , Planet Formation %R 10.11588/heidok.00007663 %T Observational studies of gas in protoplanetary disks %U https://archiv.ub.uni-heidelberg.de/volltextserver/7663/ %X The gas dominates the mass and dynamics of protoplanetary disks.However, very few observational constraints exist about the physical properties of the gas in the planet forming region of the disks. This thesis presents an ensemble of new observational projects aimed at studying the gas in the disks of selected nearby Herbig Ae/Be stars (HAEBES) and classical T Tauri stars (CTTS). In the first chapter we present a search for CO 4.7 micron ro-vibrational emission from HAEBES using ISAAC, ESO's first generation VLT near-infrared spectrograph. In the second chapter, we describe a project in which we intended to probe the outer cold gas of protoplanetary disks, by measuring gas absorption features of the disk superimposed on the optical spectra of close (< 1.5") visual companions of nearby HAEBES utilizing FORS2, ESO's VLT optical spectrograph. In the third chapter, we present a large observational effort to detect H2 fundamental rotational emission at 12.278 and 17.035 $\mu$m from HAEBES employing VISIR, ESO's new high-resolution mid-infrared spectrograph. In the fourth chapter, we describe the first results of a sensitive search for near-infrared H2 ro-vibrational emission at 2.1218, 2.2233 and 2.2477 micron in the CTTS LkHa 264 and the debris disk 49 Cet using CRIRES, ESO's new VLT near-infrared high-resolution spectrograph. From our observations (detections and non-detections), we derive important constraints on the physical properties of the studied disks (e.g. mass, column density, temperature, age, excitation mechanism, inclination). We show that high-resolution infrared spectroscopy is a crucial tool for future studies of the structure of protoplanetary disks. %Z Teile in: Astronomy and Astrophysics