A Radiatively Driven Wind from the eta Tel Debris Disk

Abstract

We present far- and near-ultraviolet absorption spectroscopy of the $\sim$23 Myr edge-on debris disk surrounding the A0V star $\eta$ Telescopii, obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph. We detect absorption lines from C I, C II, O I, Mg II, Al II, Si II, S II, Mn II, Fe II, and marginally N I. The lines show two clear absorption components at $-22.7\pm 0.5$ km s${}^{-1}$ and $-17.8\pm 0.7$ km s${}^{-1}$, which we attribute to circumstellar (CS) and interstellar (IS) gas, respectively. CO absorption is not detected, and we find no evidence for star-grazing exocomets. The CS absorption components are blueshifted by $-16.9\pm 2.6$ km s${}^{-1}$ in the star's reference frame, indicating that they are outflowing in a radiatively driven disk wind. We find that the C/Fe ratio in the $\eta$ Tel CS gas is significantly higher than the solar ratio, as is the case in the $\beta$ Pic and 49 Cet debris disks. Unlike those disks, however, the measured C/O ratio in the $\eta$ Tel CS gas is consistent with the solar value. Our analysis shows that because $\eta$ Tel is an earlier type star than $\beta$ Pic and 49 Cet, with more substantial radiation pressure at the dominant C II transitions, this species cannot bind the CS gas disk to the star as it does for $\beta$ Pic and 49 Cet, resulting in the disk wind.

arXiv commentAccepted to AJ; 24 pages, 18 figures

References in corpus (43)

• Astropy: A Community Python Package for Astronomy
• emcee: The MCMC Hammer
• The NumPy array: a structure for efficient numerical computation
• Gaia Data Release 2. Summary of the contents and survey properties
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• The Structure of the Local Interstellar Medium V: Electron Densities
• On the age of the $\beta$ Pictoris moving group
• Debris Disks: Structure, Composition, and Variability
• Spitzer IRS Spectroscopy of IRAS-Discovered Debris Disks
• Characterization of Dusty Debris Disks: the IRAS and Hipparcos Catalogs
• The MUSCLES Treasury Survey II: Intrinsic Lyman Alpha and Extreme Ultraviolet Spectra of K and M Dwarfs with Exoplanets
• Molecular Gas Clumps from the Destruction of Icy Bodies in the $\beta$ Pictoris Debris Disk
• Astrophysical supplements to the ASCC-2.5. Ia. Radial velocities of about 55000 stars and mean radial velocities of 516 Galactic open clusters and associations
• A 40 Myr Old Gaseous Circumstellar Disk at 49 Ceti: Massive CO-Rich Comet Clouds at Young A-Type Stars
• The Carbon-Rich Gas in the Beta Pictoris Circumstellar Disk
• Predictions for the secondary CO, C and O gas content of debris discs from the destruction of volatile-rich planetesimals
• A Candidate Substellar Companion to HR 7329
• GASPS - a Herschel survey of gas and dust in Protoplanetary Disks: Summary and Initial Statistics
• Exocometary gas structure, origin and physical properties around $\beta$ Pictoris through ALMA CO multi-transition observations
• Molecular gas in debris disks around young A-type stars
• Survival of icy grains in debris discs. The role of photosputtering
• High Resolution HST-STIS Spectra of CI and CO in the Beta Pictoris Circumstellar Disk
• Detection of a Millimeter Flare From Proxima Centauri
• Braking the Gas in the beta Pictoris Disk
• Gas and dust in the Beta Pictoris Moving Group as seen by the Herschel Space Observatory
• Radial Surface Density Profiles of Gas and Dust in the Debris Disk around 49 Ceti
• The Dust and Gas Around beta Pictoris
• Resolved debris disk emission around eta Tel: a young Solar System or ongoing planet formation?
• Imaging [CI] around HD 131835: reinterpreting young debris discs with protoplanetary disc levels of CO gas as shielded secondary discs
• A CO survey in planet-forming disks: characterizing the gas content in the epoch of planet formation
• Herschel HIFI observations of ionised carbon in the β Pictoris debris disk
• Volatile-Rich Circumstellar Gas in the Unusual 49 Ceti Debris Disk
• Exocomets: A spectroscopic survey
• Exposing the Gas Braking Mechanism of the beta Pictoris Disk
• Herschel detects oxygen in the beta Pictoris debris disk
• The Sizes of the Nearest Young Stars
• The co-existence of hot and cold gas in debris discs
• Expelled grains from an unseen parent body around AU Mic
• Spectroscopic metallicities of Vega-like stars
• On the unusual gas composition in the Beta Pictoris debris disk
• UV Spectroscopy of Star-Grazing Comets within the 49 Ceti Debris Disk
• The Low Velocity Wind from the Circumstellar Matter Around the B9V Star sigma Herculis
• Detection of Nitrogen gas in the $\beta$ Pictoris circumstellar disk

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