Resolving the Inner Arcsecond of the RY Tau Jet With HST

Abstract

Faint X-ray emission from hot plasma (T > 1 MK) has been detected extending outward a few arcseconds along the optically-delineated jets of some classical T Tauri stars including RY Tau. The mechanism and location where the jet is heated to X-ray temperatures is unknown. We present high spatial resolution HST far-ultraviolet long-slit observations of RY Tau with the slit aligned along the jet. The primary objective was to search for C IV emission from warm plasma at T(CIV) ~ 10${}^5$ K within the inner jet (<1 arcsec) that cannot be fully-resolved by X-ray telescopes. Spatially-resolved C IV emission is detected in the blueshifted jet extending outward from the star to 1 arcsec and in the redshifted jet out to 0.5 arcsec. C IV line centroid shifts give a radial velocity in the blueshifted jet of -136 $\pm$ 10 km/s at an offset of 0.29 arcsec (39 au) and deceleration outward is detected. The deprojected jet speed is subject to uncertainties in the jet inclination but values >200 km/s are likely. The mass-loss rate in the blueshifted jet is at least 2.3 $\times$ 10${}^{-9}$ M_sun yr${}^{-1}$, consistent with optical determinations. We use the HST data along with optically-determined jet morphology to place meaningful constraints on candidate jet-heating models including a hot-launch model in which the jet is heated near the base to X-ray temperatures by an unspecified (but probably magnetic) process, and downstream heating from shocks or a putative jet magnetic field.

21 pages, 4 tables, 7 figures

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Cited by in corpus (13)

• GIARPS High-resolution Observations of T Tauri stars (GHOsT). IV. Accretion properties of the Taurus-Auriga young association
• GIARPS High-resolution Observations of T Tauri stars (GHOsT). II. Connecting atomic and molecular winds in protoplanetary disks
• The SPHERE view of the jet and the envelope of RY Tau
• GIARPS High-resolution Observations of T Tauri stars (GHOsT). III. A pilot study of stellar and accretion properties
• GIARPS High-resolution Observations of T Tauri stars (GHOsT). I. Jet line emission
• Dynamics of wind and the dusty environments in the accreting T Tauri stars RY Tau and SU Aur
• The UV Perspective of Low-Mass Star Formation
• Time-Variable Jet Ejections from RW Aur A, RY Tau and DG Tau
• HST UV Spectroscopy of the Planet-Hosting T Tauri Star PDS 70
• Spatially resolved velocity structure in jets of DF Tau and UY Aur A
• Monitoring inner regions in the RY Tau jet
• Pre main sequence: Accretion & Outflows
• The MATISSE view of the inner region of the RY Tau protoplanetary disk