GAS in Protoplanetary Systems (GASPS): I. First results

摘要

Context. Circumstellar discs are ubiquitous around young stars, but rapidly dissipate their gas and dust on timescales of a few Myr. The Herschel Space Observatory allows for the study of the warm disc atmosphere, using far-infrared spectroscopy to measure gas content and excitation conditions, and far-IR photometry to constrain the dust distribution. Aims. We aim to detect and characterize the gas content of circumstellar discs in four targets as part of the Herschel science demonstration phase. Methods. We carried out sensitive medium resolution spectroscopy and high sensitivity photometry at λ ～ 60-190 μm using the Photodetector Array Camera and Spectrometer instrument on the Herschel Space Observatory. Results. We detect OI 63 μm emission from the young stars HD 169142, TW Hydrae, and RECX 15, but not HD 181327. No other lines, including CII 158 and OI 145, are significantly detected. All four stars are detected in photometry at 70 and 160 μm. Extensive models are presented in associated papers.