Velocity-Resolved Hot Water Emission Detected Toward Hl Tau With the Submillimeter Array

Abstract

Using the Submillimeter Array (SMA) on Mauna Kea, the H O 2 16 10 2,9 -9 3,6 transition (E up =1863 K) at 321.2 GHz has been detected toward the embedded low-mass protostar HL Tau. The line centroid is blueshifted by 20 km s −1 with respect to the source velocity, and it has a FWHM of 25 km s −1 . The emission is tentatively resolved and extends ∼3″-4″ over the sky (∼2 beams), or ∼500 au at the distance of Taurus. The velocity offset, and to a lesser degree the spatial extent of the emission, show that the line originates in the protostellar jet or wind. This result suggests that at least some water emission observed with Herschel and Spitzer toward embedded sources, and perhaps also disk sources, contains a wind or jet component, which is crucial for interpreting these data. These pathfinder observations done with the SMA open a new window into studying the origin of water emission with e.g., ALMA, thus providing new insights into where water is in protostellar systems.

Candidate Water Vapor Lines to Locate the H2O Snowline through High-dispersion Spectroscopic Observations. III. Submillimeter H2 16O and H2 18O Lines

“…Here we mention that the ortho-H 2 16 O 321 GHz line has been detected in the disk and outflow around the massive protostar candidate, Source I in Orion KL (Hirota et al 2014), using ALMA, and around the embedded low mass Class I protostar, HL Tau, using SMA (Kristensen et al 2016). The interstellar para-H 2 16 O 183 GHz and the para-H 2 18 O 203 GHz lines were detected for the first time in the Orion and DR21(OH) molecular clouds (e.g., Phillips et al 1978).…”

Candidate Water Vapor Lines to Locate the H2O Snowline Through High-dispersion Spectroscopic Observations. II. The Case of a Herbig Ae Star

“…Thus the possibility of a successful detection is expected to increase in such Herbig Ae disks and could be achieved with current ALMA capabilities. Here we mention that the 933.28 µm line has been detected with high spectral resolution in the disk and outflow around the massive protostar candidate, Source I in Orion KL (Hirota et al 2014), using ALMA, and around the embedded low mass protostar (Class I), HL Tau, using SMA (Kristensen et al 2016). Kristensen et al (2016) suggested that future observations at higher sensitivity and angular resolution with ALMA will clarify the origin of this water emission from HL Tau and resolve the disk structures.…”

Resolved ALMA observations of water in the inner astronomical units of the HL Tau disk

“…The flux is much lower than the tentative detection by ref. 20 with the Submillimeter Array, where, however, the line is shifted by 30 km s −1 from the systemic velocity, indicating that the proposed emission may be originating from a largescale flow that we filter out in our highresolution data. For the 183 and 325 GHz lines, intensityweighted velocity maps were generated using the bettermoments package 44 after applying 4σ and 3σ clipping to individual channels, respectively.…”

“…19). In quiescent sources, except the candidate detections in the AS 205N and HL Tauri (HL Tau) disks, no detection of thermal emission at (submillimetre) wavelengths has been reported in the literature [20][21][22][23] .…”