FUSE and HST STIS Observations of Hot and Cold Gas in the AB Aurigae System

Abstract

We present the first observations of a Herbig Ae star with a circumstellar disk by the Far Ultraviolet Spectroscopic Explorer (FUSE), as well as a simultaneous observation of the star obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS). The spectra of AB Aurigae show emission and absorption features arising from gasses that have a wide range in temperature, from hot OVI emission to cold molecular hydrogen and CO absorption. Emissions from the highly ionized species OVI and CIII present in the FUSE spectrum are redshifted, while absorption features arising from low-ionization species like OI, NI, and SiII are blueshifted and show characteristic stellar wind line-profiles. We find the total column density of molecular hydrogen toward AB Aur from the FUSE apectrum, N(H_2) = (6.8 +/- 0.5) x 10^19 cm^-2. The gas kinetic temperature of the molecular hydrogen derived from the ratio N(J=1)/N(J=0) is 65 +/- 4 K. The column density of the CO observed in the STIS spectrum is N(CO) = (7.1 +/- 0.5) x 10^13 cm^-2, giving a CO/H_2 ratio of (1.04 +/- 0.11) x 10^-6. We also use the STIS spectrum to find the column density of HI, permitting us to calculate the total column density of hydrogen atoms, the fractional abundance of H_2, and the gas-to-dust ratio.

5 pages, including 6 figures. LaTex2e (emulateapj5.sty). Accepted for publication in ApJ Letters

Cited by in corpus (29)

• The Mass Dependence Between Protoplanetary Disks and their Stellar Hosts
• The FUV spectrum of TW Hya. I. Observations of H${}_2$ Fluorescence
• 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
• The Far-Ultraviolet Spectra of TW Hya. II. Models of H2 Fluorescence in a Disk
• The Origins of Fluorescent H2 Emission From T Tauri~Stars
• The Case of AB Aurigae's Disk in Polarized Light: Is There Truly a Gap?
• The first high-resolution X-ray spectrum of a Herbig Star: The case of AB Aurigae
• Millimeter observations and modeling of the AB Aurigae system
• How Hot is the Wind from TW Hydrae?
• CO/H2 Abundance Ratio ~ 10^{-4} in a Protoplanetary Disk
• The chemistry of disks around T Tauri and Herbig Ae/Be stars
• The TEXES Survey For H2 Emission From Protoplanetary Disks
• The Far-Ultraviolet "Continuum" in Protoplanetary Disk Systems II: CO Fourth Positive Emission and Absorption
• Rapid Dissipation of Primordial Gas from the AU Microscopii Debris Disk
• Accretion discs as regulators of stellar angular momentum evolution in the ONC and Taurus-Auriga
• An Ordered Magnetic Field in the Protoplanetary Disk of AB Aur Revealed by Mid-Infrared Polarimetry
• Molecular hydrogen in the circumstellar environments of Herbig Ae/Be stars probed by FUSE
• CO Line Emission and Absorption from the HL Tau Disk: Where is all the dust?
• The Far-Ultraviolet "Continuum" in Protoplanetary Disk Systems I: Electron-Impact H2 and Accretion Shocks
• Chemistry in Disks. II. -- Poor molecular content of the AB Aur disk
• TEXES Observations of Pure Rotational H2 Emission From AB Aurigae
• A Low-Mass H2 Component to the AU Microscopii Circumstellar Disk
• FUSE observations of H2 around the Herbig AeBe stars HD 100546 and HD 163296
• A search for H2 around pre-main-sequence stars
• Observational diagnostics of gas in protoplanetary disks
• CO and H2 Absorption in the AA Tauri Circumstellar Disk
• Where is the warm H2 ? A search for H2 emission from disks around Herbig Ae/Be stars
• FUSE observations of molecular hydrogen on the line of sight towards HD141569A
• Magnetism, rotation and accretion in Herbig Ae-Be stars