INFALLING-ROTATING MOTION and ASSOCIATED CHEMICAL CHANGE in the ENVELOPE of IRAS 16293-2422 SOURCE A STUDIED with ALMA

Yoko Oya, Nami Sakai, Ana López-Sepulcre, Yoshimasa Watanabe, Cecilia Ceccarelli, Bertrand Lefloch, Cécile Favre, Satoshi Yamamoto

Research output: Contribution to journalArticle

63 Citations (Scopus)

Abstract

We have analyzed rotational spectral line emission of OCS, CH3OH, HCOOCH3, and H2CS observed toward the low-mass Class 0 protostellar source IRAS 16293-2422 Source A at a sub-arcsecond resolution (∼0.″6 0.″5) with ALMA. Significant chemical differentiation is found on a scale of 50 au. The OCS line is found to trace well the infalling-rotating envelope in this source. On the other hand, the distributions of CH3OH and HCOOCH3 are found to be concentrated around the inner part of the infalling-rotating envelope. With a simple ballistic model of the infalling-rotating envelope, the radius of the centrifugal barrier (a half of the centrifugal radius) and the protostellar mass are evaluated from the OCS data to be from 40 to 60 au and from 0.5 to 1.0 M o, respectively, assuming the inclination angle of the envelope/disk structure to be 60° (90° for the edge-on configuration). Although the protostellar mass is correlated with the inclination angle, the radius of the centrifugal barrier is not. This is the first indication of the centrifugal barrier of the infalling-rotating envelope in a hot corino source. CH3OH and HCOOCH3 may be liberated from ice mantles by weak accretion shocks around the centrifugal barrier and/or by protostellar heating. The H2CS emission seems to come from the disk component inside the centrifugal barrier in addition to the envelope component. The centrifugal barrier plays a central role not only in the formation of a rotationally supported disk but also in the chemical evolution from the envelope to the protoplanetary disk.

Original languageEnglish
Article number88
JournalAstrophysical Journal
Volume824
Issue number2
DOIs
Publication statusPublished - 2016 Jun 20
Externally publishedYes

Keywords

  • ISM: individual objects (IRAS 16293-2422)
  • ISM: molecules
  • stars: formation
  • stars: pre-main sequence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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