Chin-Fei Lee^1,2, Claudio Codella^3,4, Zhi-Yun Li⁵, and Sheng-Yuan Liu¹
Astrophysical Journal 876, 63 Link to Article [DOI: 10.3847/1538-4357/ab15db ]
¹Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan
²Graduate Institute of Astronomy and Astrophysics, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
³INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy
⁴Univ. Grenoble Alpes, CNRS, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), F-38000 Grenoble, France
⁵Astronomy Department, University of Virginia, Charlottesville, VA 22904, USA

HH 212 is one of the well-studied protostellar systems, showing the first vertically resolved disk with a warm atmosphere around the central protostar. Here we report a detection of nine organic molecules (including newly detected ketene, formic acid, deuterated acetonitrile, methyl formate, and ethanol) in the disk atmosphere, confirming that the disk atmosphere is, for HH 212, the chemically rich component, identified before at a lower resolution as a “hot corino.” More importantly, we report the first systematic survey and abundance measurement of organic molecules in the disk atmosphere within ~40 au of the central protostar. The relative abundances of these molecules are similar to those in the hot corinos around other protostars and in Comet Lovejoy. These molecules can be either (i) originally formed on icy grains and then desorbed into gas phase or (ii) quickly formed in the gas phase using simpler species ejected from the dust mantles. The abundances and spatial distributions of the molecules provide strong constraints on models of their formation and transport in star formation. These molecules are expected to form even more complex organic molecules needed for life and deeper observations are needed to find them.

D. Estrella-Trujillo¹, L. Hernández-Martínez¹, P. F. Velázquez¹, A. Esquivel^1,2, and A. C. Raga¹
Astrophysical Journal 876, 29 Link to Article [DOI: 10.3847/1538-4357/ab12e1 ]
¹Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México. Apartado Postal 70-543, 04510 Ciudad de México, México
²Instituto de Astronomía Teórica y Experimental, Universidad Nacional de Córdoba, X500BGR Córdoba, Argentina

We have carried out 3D hydrodynamic simulations of a precessing jet/counterjet ejection. We have included the photoionization from the central source, considering three different ionizing photon rates (, 10⁴⁶, and 10⁴⁷ phots s⁻¹), in order to determine its effect on the morphology and kinematics of the protoplanetary nebula. We have considered a time-dependent ejection density that generates dense knot structures in the jet, which are then partially photoionized by the ionizing photon field from the central source. We also explore the role of the medium in which the jet is propagated, under these conditions. The photoionization results in a larger Hα emission of the knots, and in an acceleration of the knots as a result of the so-called “rocket effect.” We find that for larger values of the ionizing photon rate, a clear outwards acceleration of the knots is produced. These models are appropriate for explaining protoplanetary nebulae in which such outwards accelerations are observed.