[seminar] Astro Journal Club on 16 December

[Oskari Miettinen]

Dear all,

Our Astro Journal Club will be held on Wednesday at 3:00 pm (sharp) in the
seminar room F-201 of the Physics Department. This time we will discuss
about the new ALMA observations of the Galactic high-mass star-forming
region Sgr B2(N).

Presenter: Krešimir Tisanić
Paper title: Sgr B2(N): A bipolar outflow and rotating hot core revealed
by ALMA
Authors: Higuchi, A. E., Hasegawa, T., Saigo, K., et al.

Summary:
We present the results of SiO (2-1) and SO2 (12-13) line observations of
Sgr B2(N) made with the Atacama Large Millimeter/submillimeter Array
(ALMA) at an angular resolution of 2arcsec. Our analysis of the SiO and
SO2 line emission reveals a bipolar molecular outflow in an east-west
direction whose driving source is located at K2. In addition, SO2 line
core shows a north-south velocity gradient most probably indicating a hot
core of molecular gas rotating around K2. Fractional abundances of SO2 and
SiO (X(SO2) and X(SiO), respectively) in the outflowing molecular gas are
derived from comparisons with the C18O emission. Assuming an excitation
temperature of 100+-50 K, we calculate X(SO2) = 2.3e-8 and X(SiO) =
1.2e-9. The outflow from SgrB2(N) K2 is characterized as a young (5000 yr)
and massive (2000 Msun), but moderately collimated (60deg) 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 4th
star forming region associated with SiO masers.

Link to the paper: http://adsabs.harvard.edu/abs/2015arXiv151102955H

See you all on Wednesday!

Note: This will be our last journal club before Christmas break. Thank you
to all the speakers and attendees of our journal club this year! We will
be back next year!

Cheers,
Oskari