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Title: A CHEMICAL VIEW OF PROTOSTELLAR-DISK FORMATION IN L1527

Subarcsecond images of the rotational line emissions of CCH, CS, H{sub 2}CO, and CH{sub 3}OH have been obtained toward the low-mass protostar IRAS 04368+2557 in L1527 as one of the early science projects of the Atacama Large Millimeter/submillimeter Array. The intensity distributions of CCH and CS show a double-peaked structure along the edge-on envelope with a dip toward the protostar position, whereas those of H{sub 2}CO and CH{sub 3}OH are centrally peaked. By analyzing the position-velocity diagrams along the envelope, CCH and CS are found to reside mainly in the envelope, where the gas is infalling with conservation of its angular momentum. They are almost absent inward of the centrifugal barrier (a half of the centrifugal radius). Although H{sub 2}CO exists in the infalling rotating envelope, it also resides in the disk component inside the centrifugal barrier to some extent. On the other hand, CH{sub 3}OH seems to exist around the centrifugal barrier and in the disk component. Hence, the drastic chemical change occurs at the centrifugal barrier. A discontinuous infalling motion as well as the gas-grain interaction would be responsible for the chemical change. This result will put an important constraint on initial chemical compositions for chemical evolution of protostellarmore » disks.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ; ; ; ;  [4] ; ; ;  [5] ;  [6] ;  [7] ; ;  [8] ;  [9]
  1. Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)
  2. Department of Communication Engineering and Informatics, Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofugaoka, Chofu, Tokyo 182-8585 (Japan)
  3. National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)
  4. Universite de Grenoble Alpes, IPAG, F-38000 Grenoble (France)
  5. Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France)
  6. Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø. (Denmark)
  7. Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan)
  8. Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China)
  9. Subaru Telescope, National Astronomical Observatory of Japan, 650 North A Aoohoku Place, Hilo, HI 96720 (United States)
Publication Date:
OSTI Identifier:
22365252
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 791; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANGULAR MOMENTUM; CHEMICAL COMPOSITION; DIAGRAMS; IMAGES; LIMITING VALUES; MASS; METHANOL; MOLECULES; PROTOSTARS; STAR EVOLUTION; STARS; VELOCITY