Molecular hydrogen in the disk of the Herbig Ae star HD97048

Abstract

We present high-resolution spectroscopic mid-infrared observations of the circumstellar disk around the Herbig Ae star HD97048 obtained with the VLT Imager and Spectrometer for the mid-InfraRed (VISIR). We conducted observations of mid-infrared pure rotational lines of molecular hydrogen (H2) as a tracer of warm gas in the disk surface layers. In a previous paper, we reported the detection of the S(1) pure rotational line of H2 at 17.035 microns and argued it is arising from the inner regions of the disk around the star. We used VISIR on the VLT for a more comprehensive study based on complementary observations of the other mid-infrared molecular transitions, namely S(2) and S(4) at 12.278 microns and 8.025 microns respectively, to investigate the physical properties of the molecular gas in the circumstellar disk around HD97048. We do not detect neither the S(2) line nor the S(4) H2 line from the disk of HD97048, but we derive upper limits on the integrated line fluxes which allows us to estimate an upper limit on the gas excitation temperature, T_ex < 570 K. This limit on the temperature is consistent with the assumptions previously used in the analysis of the S(1) line, and allows us to set stronger contraints on the mass of warm gas in the inner regions of the disk. Indeed, we estimate the mass of warm gas to be lower than 0.1 M_Jup. We also discuss the probable physical mechanisms which could be responsible of the excitation of H2 in the disk of HD97048.

accepted for publication in ApJ

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Cited by in corpus (7)

• A cavity and further radial substructures in the disk around HD~97048
• The unusual protoplanetary disk around the T Tauri star ET Cha
• ALMA reveals the anatomy of the mm-sized dust and molecular gas in the HD 97048 disk
• DIGIT survey of far-infrared lines from protoplanetary discs: II. CO
• A CO survey in planet-forming disks: characterizing the gas content in the epoch of planet formation
• Resolving the inner regions of the HD97048 circumstellar disk with VLT/NACO polarimetric differential imaging
• Where is the warm H2 ? A search for H2 emission from disks around Herbig Ae/Be stars