Having disk-to-star accretion rates on the order of 10-4 M☉/yr, FU Orionis-type stars (FUors) are thought to be the visible examples for episodic accretion. FUors are often surrounded by massive envelopes, which replenish the disk material and enable the disk to produce accretion outbursts. We observed the FUor-type star V346 Nor with ALMA at 1.3 mm continuum and in different CO rotational lines. We mapped the density and velocity structure of its envelope and analyzed the results using channel maps, position-velocity diagrams, and spectro-astrometric methods. We discovered a pseudo-disk and a Keplerian disk around a 0.1 M☉ central star. We determined an infall rate from the envelope onto the disk of 6×10-6 M☉ /yr, a factor of few higher than the quiescent accretion rate from the disk onto the star. This hints for a mismatch between the infall and accretion rates as the cause of the eruption.
- Pub Date:
- stars: pre-main-sequence;
- accretion disks;
- circumstellar matter;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- 2 pages, 1 figure, published in "Origins: From the Protosun to the First Steps of Life. Proceedings of the International Astronomical Union, Volume 345"