Volume 584, December 2015
|Number of page(s)||5|
|Published online||19 November 2015|
High-mass star-forming cloud G0.38+0.04 in the Galactic center dust ridge contains H2CO and SiO masers⋆
1 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
2 International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth WA 6845, Australia
3 Max–Planck–Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
4 Astron. Dept., King Abdulaziz University, PO Box 80203, 21589 Jeddah, Saudi Arabia
5 School of Physics, University of New South Wales, Sydney NSW 2052, Australia
6 CSIRO Astronomy and Space Science, PO Box 76, Epping, NSW 1710, Australia
7 National Radio Astronomy Observatory, 1003 Lopezville Rd, Socorro, NM 87801, USA
8 Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, 69120 Heidelberg, Germany
9 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
10 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
11 Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
12 Department of Physics and Astronomy and MQ Research Centre in Astronomy, Astrophysics and Astrophotonics, Macquarie University, NSW 2109, Australia
Received: 25 September 2015
Accepted: 20 October 2015
We have discovered a new H2CO (formaldehyde) 11,0−11,1 4.82966 GHz maser in Galactic center Cloud C, G0.38+0.04. At the time of acceptance, this is the eighth region to contain an H2CO maser detected in the Galaxy. Cloud C is one of only two sites of confirmed high-mass star formation along the Galactic center ridge, affirming that H2CO masers are exclusively associated with high-mass star formation. This discovery led us to search for other masers, among which we found new SiO vibrationally excited masers, making this the fourth star-forming region in the Galaxy to exhibit SiO maser emission. Cloud C is also a known source of CH3OH Class-II and OH maser emission. There are now two known regions that contain both SiO and H2CO masers in the CMZ, compared to two SiO and six H2CO in the Galactic disk, while there is a relative dearth of H2O and CH3OH Class-II masers in the CMZ. SiO and H2CO masers may be preferentially excited in the CMZ, perhaps because of higher gas-phase abundances from grain destruction and heating, or alternatively H2O and CH3OH maser formation may be suppressed in the CMZ. In any case, Cloud C is a new testing ground for understanding maser excitation conditions.
Key words: radio lines: ISM / Galaxy: center / ISM: clouds / ISM: molecules / ISM: individual objects: G0.38+0.04 / masers
Appendices are available in electronic form at http://www.aanda.org
© ESO, 2015
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.