Searching for molecular hydrogen mid-infrared emission in the circumstellar environments of Herbig Be stars

Abstract

Context: Molecular hydrogen (H2) is the most abundant molecule in the circumstellar (CS) environments of young stars, and is a key element in giant planet formation. The measurement of the H2 content provides the most direct probe of the total amount of CS gas, especially in the inner warm planet-forming regions of the disks. Aims: Most Herbig Be stars (HBes) are distant from the Sun and their nature and evolution are still debated. We therefore conducted mid-infrared observations of H2 as a tracer of warm gas around HBes known to have gas-rich CS environments. Methods: We report a search for the H2 S(1) emission line at 17.0348 microns in the CS environments of 5 HBes with the high resolution spectroscopic mode of VISIR (ESO VLT Imager and Spectrometer for the mid-InfraRed). Results: No source shows evidence for H2 emission at 17.0348 microns. Stringent 3sigma upper limits on the integrated line fluxes are derived. Depending on the adopted temperature, limits on column densities and masses of warm gas are also estimated. These non-detections constrain the amount of warm (>150 K) gas in the immediate CS environments of our target stars to be less than 1-10 Jupiter masses.

Research Note accepted for publication in A&A, 5 pages, 1 figure, 2 tables

References in corpus (14)

• ISO spectroscopy of circumstellar dust in 14 Herbig Ae/Be systems: towards an understanding of dust processing
• A model for atomic and molecular interstellar gas: The Meudon PDR code
• H2 and CO emission from disks around TTauri and HerbigAe pre-main-sequence stars and from debris disks around young stars: warm and cold circumstellar gas
• [O I] 6300A emission in Herbig Ae/Be systems: signature of Keplerian rotation
• Probing the circumstellar structure of Herbig Ae/Be stars
• Warm Gas in the Inner Disks around Young Intermediate Mass Stars
• c2d Spitzer IRS Spectra of Disks around T Tauri Stars. III. [Ne II], [Fe I], and H_2 gas-phase lines
• Near infrared and the inner regions of protoplanetary disks
• A Search for Mid-Infrared Molecular Hydrogen Emission from Protoplanetary Disks
• Looking for Pure Rotational H_2 Emission from Protoplanetary Disks
• Molecular hydrogen in the circumstellar environments of Herbig Ae/Be stars probed by FUSE
• TEXES Observations of Pure Rotational H2 Emission From AB Aurigae
• Detection of warm molecular hydrogen in the circumstellar disk around the Herbig Ae star HD97048
• Analysis of the circumstellar environment of the B[e] star HD 45677 (FS CMa)

Cited by in corpus (4)

• A survey for near-infrared H2 emission in Herbig Ae/Be stars: emission from the outer disks of HD 97048 and HD 100546
• A CO survey in planet-forming disks: characterizing the gas content in the epoch of planet formation
• Observational diagnostics of gas in protoplanetary disks
• Where is the warm H2 ? A search for H2 emission from disks around Herbig Ae/Be stars