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Title: UNVEILING THE EVOLUTIONARY SEQUENCE FROM INFALLING ENVELOPES TO KEPLERIAN DISKS AROUND LOW-MASS PROTOSTARS

Abstract

We performed Submillimeter Array observations in the C{sup 18}O (2-1) emission line toward six Class 0 and I protostars to study rotational motions of their surrounding envelopes and circumstellar material on 100-1000 AU scales. C{sup 18}O (2-1) emission with intensity peaks located at the protostellar positions is detected toward all six sources. The rotational velocities of the protostellar envelopes as a function of radius were measured from the position-velocity diagrams perpendicular to the outflow directions passing through the protostellar positions. Two Class 0 sources, B335 and NGC 1333 IRAS 4B, show no detectable rotational motion, while L1527 IRS (Class 0/I) and L1448-mm (Class 0) exhibit rotational motions with radial profiles of V{sub rot}{proportional_to}r {sup -1.0{+-}0.2} and {proportional_to}r {sup -1.0{+-}0.1}, respectively. The other Class I sources, TMC-1A and L1489 IRS, exhibit the fastest rotational motions among the sample, and their rotational motions have flatter radial profiles of V{sub rot}{proportional_to}r {sup -0.6{+-}0.1} and {proportional_to}r {sup -0.5{+-}0.1}, respectively. The rotational motions with the radial dependence of {approx}r {sup -1} can be interpreted as rotation with a conserved angular momentum in a dynamically infalling envelope, while those with the radial dependence of {approx}r {sup -0.5} can be interpreted as Keplerian rotation. These observational resultsmore » demonstrate categorization of rotational motions from infalling envelopes to Keplerian-disk formation. Models of the inside-out collapse where the angular momentum is conserved are discussed and compared with our observational results.« less

Authors:
 [1]; ; ;  [2]
  1. Institute of Astrophysics, National Taiwan University, Taipei 10617, Taiwan (China)
  2. Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China)
Publication Date:
OSTI Identifier:
22121879
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 772; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; ANGULAR MOMENTUM; DWARF STARS; EMISSION; MASS; PROTOSTARS; RADIAL VELOCITY; ROTATION; STAR EVOLUTION

Citation Formats

Yen, Hsi-Wei, Takakuwa, Shigehisa, Ohashi, Nagayoshi, and Ho, Paul T. P.,. UNVEILING THE EVOLUTIONARY SEQUENCE FROM INFALLING ENVELOPES TO KEPLERIAN DISKS AROUND LOW-MASS PROTOSTARS. United States: N. p., 2013. Web. doi:10.1088/0004-637X/772/1/22.
Yen, Hsi-Wei, Takakuwa, Shigehisa, Ohashi, Nagayoshi, & Ho, Paul T. P.,. UNVEILING THE EVOLUTIONARY SEQUENCE FROM INFALLING ENVELOPES TO KEPLERIAN DISKS AROUND LOW-MASS PROTOSTARS. United States. https://doi.org/10.1088/0004-637X/772/1/22
Yen, Hsi-Wei, Takakuwa, Shigehisa, Ohashi, Nagayoshi, and Ho, Paul T. P.,. 2013. "UNVEILING THE EVOLUTIONARY SEQUENCE FROM INFALLING ENVELOPES TO KEPLERIAN DISKS AROUND LOW-MASS PROTOSTARS". United States. https://doi.org/10.1088/0004-637X/772/1/22.
@article{osti_22121879,
title = {UNVEILING THE EVOLUTIONARY SEQUENCE FROM INFALLING ENVELOPES TO KEPLERIAN DISKS AROUND LOW-MASS PROTOSTARS},
author = {Yen, Hsi-Wei and Takakuwa, Shigehisa and Ohashi, Nagayoshi and Ho, Paul T. P.,},
abstractNote = {We performed Submillimeter Array observations in the C{sup 18}O (2-1) emission line toward six Class 0 and I protostars to study rotational motions of their surrounding envelopes and circumstellar material on 100-1000 AU scales. C{sup 18}O (2-1) emission with intensity peaks located at the protostellar positions is detected toward all six sources. The rotational velocities of the protostellar envelopes as a function of radius were measured from the position-velocity diagrams perpendicular to the outflow directions passing through the protostellar positions. Two Class 0 sources, B335 and NGC 1333 IRAS 4B, show no detectable rotational motion, while L1527 IRS (Class 0/I) and L1448-mm (Class 0) exhibit rotational motions with radial profiles of V{sub rot}{proportional_to}r {sup -1.0{+-}0.2} and {proportional_to}r {sup -1.0{+-}0.1}, respectively. The other Class I sources, TMC-1A and L1489 IRS, exhibit the fastest rotational motions among the sample, and their rotational motions have flatter radial profiles of V{sub rot}{proportional_to}r {sup -0.6{+-}0.1} and {proportional_to}r {sup -0.5{+-}0.1}, respectively. The rotational motions with the radial dependence of {approx}r {sup -1} can be interpreted as rotation with a conserved angular momentum in a dynamically infalling envelope, while those with the radial dependence of {approx}r {sup -0.5} can be interpreted as Keplerian rotation. These observational results demonstrate categorization of rotational motions from infalling envelopes to Keplerian-disk formation. Models of the inside-out collapse where the angular momentum is conserved are discussed and compared with our observational results.},
doi = {10.1088/0004-637X/772/1/22},
url = {https://www.osti.gov/biblio/22121879}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 772,
place = {United States},
year = {Sat Jul 20 00:00:00 EDT 2013},
month = {Sat Jul 20 00:00:00 EDT 2013}
}