Early Planet Formation in Embedded Disks (eDisk): A first-look results of the Class 0 protostar IRAS 04166+2706

Phuong Thi Nguyen

We present ALMA observations of the Class 0 protostar IRAS 04166+2706 as a part of the ALMA large program eDisk (Early Planet Formation in Embedded Disks). Using Band 6, we observed the 1.3 mm emission from dust at angular resolution of ~au, and CO,
13CO, C18O J=2--1, H2CO, and Ch3OH lines at the angular resolution of ~25au. The continuum emission reveals the 22 au disk-like structure elongated in the direction of P.A.=122 deg east of the north, and inclined by 47 deg with respect to the plane sky. By fitting both in the image plane and in the visibility, we found that the dust contains a concentric ring. The location of the dust ring at 13 au is consistent with the expectation of the dust ring formed by a recently proposed dust coagulation mechanism. Using Position-Velocity analysis of 13CO and C18O, we find that the molecules trace the infalling-rotating envelope. Assuming a Keplerian gas rotation, we derive the upper and lower limit of the protostellar mass to be 0.13 Msun to 0.25Msun. The CO traces a bipolar outflow confined to the wall of two opposed conical shells, and highly collimated jets simultaneously with the sign of episodic mass ejection at the time scale of ~ 120 years. The SiO emission shows highly collimated jets at high velocity like in the CO jets. Besides, the h2CO traces the infalling motion closer to the central protostar and CH3OH has been detected inside the dust disk, which can be explained by high-temperature sublimation.