STRUCTURE AND DYNAMICS OF THE ACCRETION PROCESS AND WIND IN TW Hya

Time-domain spectroscopy of the classical accreting T Tauri star, TW Hya, covering a decade and spanning the far UV to the near-infrared spectral regions can identify the radiation sources, the atmospheric structure produced by accretion, and properties of the stellar wind. On timescales from days t...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal 2014-07, Vol.789 (1), p.1-17
Main Authors: Dupree, A K, Brickhouse, N S, Cranmer, S R, Berlind, P, Strader, Jay, Smith, Graeme H
Format: Article
Language:English
Subjects:
ABSORPTION
Accretion
ACCRETION DISKS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
DIPOLES
EMISSION
HYDROGEN
Mathematical models
OPACITY
Outflow
RADIATION SOURCES
SAMPLING
SCATTERING
SPECTROSCOPY
Stars
STELLAR WINDS
STREAMS
Strength
T TAURI STARS
VELOCITY
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Time-domain spectroscopy of the classical accreting T Tauri star, TW Hya, covering a decade and spanning the far UV to the near-infrared spectral regions can identify the radiation sources, the atmospheric structure produced by accretion, and properties of the stellar wind. On timescales from days to years, substantial changes occur in emission line profiles and line strengths. Our extensive time-domain spectroscopy suggests that the broad near-IR, optical, and far-uv emission lines, centered on the star, originate in a turbulent post-shock region and can undergo scattering by the overlying stellar wind as well as some absorption from infalling material. Stable absorption features appear in H alpha , apparently caused by an accreting column silhouetted in the stellar wind. Inflow of material onto the star is revealed by the near-IR He I 10830 A line, and its free-fall velocity correlates inversely with the strength of the post-shock emission, consistent with a dipole accretion model. However, the predictions of hydrogen line profiles based on accretion stream models are not well-matched by these observations. Evidence of an accelerating warm to hot stellar wind is shown by the near-IR He I line, and emission profiles of C II, C III, C IV, N V, and O VI. The outflow of material changes substantially in both speed and opacity in the yearly sampling of the near-IR He I line over a decade. Terminal outflow velocities that range from 200 km s super(-1) to almost 400 km s super(-1) in He I appear to be directly related to the amount of post-shock emission, giving evidence for an accretion-driven stellar wind. Calculations of the emission from realistic post-shock regions are needed.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/789/1/27