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2w ago

Gas Streamer Likely Tilted GW Orionis' Triple-Star Disk

ALMA observations tie an inflowing river of molecular gas to the disk's outer ring, showing external accretion can change a young disk's tilt and so alter where planets form.

Magnetic loops carry gas and dust above disks of planet-forming material circling stars, as shown in this artist's conception. These loops give off extra heat, which NASA's Spitzer Space Telescope detects as infrared light. The colors in this illustration show what an alien observer with eyes sensitive to both visible light and infrared waveleng. Image credit: NASA/JPL-Caltech

Overview

  • The Astronomical Journal paper, which published Aug. 6, reported ALMA 12CO and 13CO maps that reveal a streamer roughly 30 arcseconds long (about 12,000 AU) feeding GW Orionis' circumtriple disk.
  • The team estimates the streamer contains about 1.6 Jupiter masses and is falling in on a timescale of roughly 0.04 million years at a rate near 3.6×10⁻⁸ solar masses per year.
  • Kinematic fits show the streamer's angular momentum is aligned with the outermost dust ring to within about 3 degrees and is misaligned by about 32 degrees with the inner ring, supporting a causal link to the disk's warped geometry.
  • ALMA Total Power data connect the streamer back to the surrounding star-forming cloud and place GW Orionis within a Bondi–Hoyle radius, suggesting the gas was captured from the natal cloud as the system moved through it.
  • The authors caution that the streamer carries less total angular momentum than the disk and that its infall rate is lower than the stars' accretion, so this event may be late or incomplete and calls for surveys to see how often such streamers reshape planet-forming disks.