How Hot Is the Wind from Tw Hydrae?

It has recently been suggested that the winds from classical T Tauri stars in general, and the wind from TWHya in particular, reaches temperatures of 300,000 Kwhile maintaining a mass-loss rate of 10 M yr 1 or larger. If confirmed, this would place strong new requirements on wind launching and heating models. We therefore reexamine spectra from the Space Telescope Imaging Spectrograph aboard theHubble Space Telescope and spectra from theFar Ultraviolet Spectroscopic Explorer satellite in an effort to better constrain the maximum temperature in the wind of TWHya.We find clear evidence for a wind in the C ii doublet at 10378 and in the C iimultiplet at 13358. We find no wind absorption in the C iv k1550 doublet observed at the same time as the C ii k1335 line or in observations of O vi observed simultaneously with the C ii k1037 line. The presence or absence of C iiiwind absorption is ambiguous. The clear lack of a wind in the C iv line argues that the wind from TW Hya does not reach the 100,000 K characteristic formation temperature of this line. We therefore argue that the available evidence suggests that the wind from TW Hya, and perhaps all classical T Tauri stars, reaches a maximum temperature in the range of 10,000–30,000 K. Subject headingg s: accretion, accretion disks — stars: individual (TW Hydrae) — stars: mass loss — stars: pre–main-sequence