Arcsecond-resolution submillimeter HCN imaging of the binary protostar IRAS 16293-2422
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Arcsecond-resolution submillimeter HCN imaging of the binary protostar IRAS 16293-2422. / Takakuwa, Shigehisa; Ohashi, Nagayoshi; Bourke, Tyler L.; Hirano, Naomi; Paul, T. P.Ho; Jørgensen, Jes K.; Kuan, Y. I.Jehng; Wilner, David J.; Yeh, Sherry C.C.
In: Astrophysical Journal, Vol. 662, No. 1 I, 10.06.2007, p. 431-442.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Arcsecond-resolution submillimeter HCN imaging of the binary protostar IRAS 16293-2422
AU - Takakuwa, Shigehisa
AU - Ohashi, Nagayoshi
AU - Bourke, Tyler L.
AU - Hirano, Naomi
AU - Paul, T. P.Ho
AU - Jørgensen, Jes K.
AU - Kuan, Y. I.Jehng
AU - Wilner, David J.
AU - Yeh, Sherry C.C.
PY - 2007/6/10
Y1 - 2007/6/10
N2 - With the Submillimeter Array (SMA) we have made high angular resolution (∼1″ = 160 AU ) observations of the protobinary system IRAS 16293-2422 in the HCN (4-3), HC15N (4-3), and 354.5 GHz continuum emission. The HCN (4-3) line was also observed using the JCMT to supply missing short-spacing information. The submillimeter continuum emission is detected from the individual binary components of source A in the southeast and source B in the northwest, with a separation of ∼5″. The optically thin HC 15N (4-3) emission taken with the SMA has revealed a compact (∼500 AU) flattened structure (P.A. = -16°) at source A. This compact structure shows a velocity gradient along the projected minor axis, which can be interpreted as an infalling gas motion. Our HCN image including the short-spacing information shows an extended (∼3000 AU ) circumbinary envelope, as well as the compact structure at source A. A toy model consisting of a flattened structure with radial infall toward a 1 M∞ central star reproduces the HCN/HC15N position-velocity diagram along the minor axis of the HC15N emission. In the extended envelope there is also a northeast (blue) to southwest (red) velocity gradient across the binary alignment, which is likely to reflect gas motion in the swept-up dense gas associated with the molecular outflow from source A. Only a weak and narrow (∼2 km s-1) compact HC15N emission is associated with source B, where no clear molecular outflow is identified, suggesting the different evolutionary starges between sources A and B. Our study demonstrates the importance of adding short-spacing data to interferometer data in order to probe the detailed structure and kinematics of low-mass protostellar envelopes.
AB - With the Submillimeter Array (SMA) we have made high angular resolution (∼1″ = 160 AU ) observations of the protobinary system IRAS 16293-2422 in the HCN (4-3), HC15N (4-3), and 354.5 GHz continuum emission. The HCN (4-3) line was also observed using the JCMT to supply missing short-spacing information. The submillimeter continuum emission is detected from the individual binary components of source A in the southeast and source B in the northwest, with a separation of ∼5″. The optically thin HC 15N (4-3) emission taken with the SMA has revealed a compact (∼500 AU) flattened structure (P.A. = -16°) at source A. This compact structure shows a velocity gradient along the projected minor axis, which can be interpreted as an infalling gas motion. Our HCN image including the short-spacing information shows an extended (∼3000 AU ) circumbinary envelope, as well as the compact structure at source A. A toy model consisting of a flattened structure with radial infall toward a 1 M∞ central star reproduces the HCN/HC15N position-velocity diagram along the minor axis of the HC15N emission. In the extended envelope there is also a northeast (blue) to southwest (red) velocity gradient across the binary alignment, which is likely to reflect gas motion in the swept-up dense gas associated with the molecular outflow from source A. Only a weak and narrow (∼2 km s-1) compact HC15N emission is associated with source B, where no clear molecular outflow is identified, suggesting the different evolutionary starges between sources A and B. Our study demonstrates the importance of adding short-spacing data to interferometer data in order to probe the detailed structure and kinematics of low-mass protostellar envelopes.
KW - ISM: individual (IRAS 16293-2422)
KW - ISM: molecules
KW - Stars: formation
UR - http://www.scopus.com/inward/record.url?scp=34347239286&partnerID=8YFLogxK
U2 - 10.1086/513589
DO - 10.1086/513589
M3 - Journal article
AN - SCOPUS:34347239286
VL - 662
SP - 431
EP - 442
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1 I
ER -
ID: 234018448