Sgr B2(N): A bipolar outflow and rotating hot core revealed by ALMA

Journal Article · Sun Dec 20 04:00:00 EST 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/815/2/106· OSTI ID:22882342

Higuchi, Aya E. ^[1]; Hasegawa, Tetsuo; Sanhueza, Patricio ^[2]; Saigo, Kazuya ^[3]

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1. College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, 310-8512 (Japan)
2. National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 (Japan)
3. Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan)

We present the results of SiO (2 − 1) and SO{sub 2} (12{sub 4,8}--13{sub 3,11}) line observations of Sgr B2(N) made with the Atacama Large Millimeter/submillimeter Array at an angular resolution of ∼2″. Our analysis of the SiO and SO{sub 2} line emission reveals a bipolar molecular outflow in an east–west direction whose driving source is located at K2. In addition, the SO{sub 2} line core shows a north–south velocity gradient most probably indicating a hot core of molecular gas rotating around K2. Fractional abundances of SO{sub 2} and SiO (X(SO{sub 2}) and X(SiO), respectively) in the outflowing molecular gas are derived from comparisons with the C{sup 18}O emission. Assuming an excitation temperature of 100 ± 50 K, we calculate X(SO{sub 2}) = 2.3{sub −0.4}{sup +2.6} × 10{sup −8} and X(SiO) = 1.2{sub −0.1}{sup +0.1} × 10{sup −9}. The outflow from Sgr B2(N) K2 is characterized as a young (5 × 10{sup 3} yr) and massive (∼2000 M{sub ⊙}) but moderately collimated (∼60°) outflow. We also report a possible detection of the SiO (v=2,J=2--1) maser emission from the position of K2. If confirmed, it would make Sgr B2(N) the fourth star-forming region associated with SiO masers.

• OSTI ID: 22882342
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 815; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPARATIVE EVALUATIONS
COSMIC GASES
ELEMENT ABUNDANCE
EMISSION
EXCITATION
MASERS
MOLECULES
SILICON OXIDES
STARS
SULFUR DIOXIDE
VELOCITY