Discovery of Two New Class II Methanol Maser Transitions in G345.01+1.79

Abstract

We have used the Swedish ESO Submillimetre Telescope (SEST) to search for new class II methanol maser transitions towards the southern source G345.01+1.79. Over a period of 5 days we observed 11 known or predicted class II methanol maser transitions. Emission with the narrow line width and characteristic velocity of class II methanol masers (in this source) was detected in 8 of these transitions, two of which have not previously been reported as masers. The new class II methanol maser transitions are the 13(-3)-12(-4)E transition at 104.1 GHz and the 5(1)-4(2)E transition at 216.9 GHz. Both of these are from transition series for which there are no previous known class II methanol maser transitions. This takes the total number of known class II methanol maser series to 10, and the total number of transitions (or transition groups) to 18. The observed 104.1 GHz maser suggests the presence of two or more regions of masing gas with similar line of sight velocities, but quite different physical conditions. Although these newly discovered transitions are likely to be relatively rare, where they are observed combined studies using the Australia Telescope Compact Array and the Atacama Large Millimeter Array offer the prospect to be able to undertake multi-transition methanol maser studies with unprecedented detail.

8 pages, 3 figures, accepted for publication in ApJ Letters

References in corpus (1)

• A Class I and Class II Methanol Maser Survey of Extended Green Objects (EGOs) from the GLIMPSE Survey

Cited by in corpus (12)

• Southern class I methanol masers at 36 and 44 GHz
• Discovery of six new class II methanol maser transitions, including the unambiguous detection of three torsionally excited lines toward G358.931-0.030
• Survey of Water and Ammonia in Nearby galaxies (SWAN): Resolved Ammonia Thermometry, Water and Methanol Masers in the Nuclear Starburst of NGC 253
• Detection of 36 GHz class I methanol maser emission towards NGCS253
• A search for water masers associated with class II methanol masers - II. Longitude range 341${}^{\circ }$ to 6${}^{\circ }$
• Testing maser-based evolutionary schemes: A new search for 37.7-GHz methanol masers
• The relationship between Class I and Class II methanol masers at high angular resolution
• The first high-resolution observations of 19.9-GHz methanol masers
• The Science Case for Simultaneous mm-Wavelength Receivers in Radio Astronomy
• Redshifted methanol absorption tracing infall motions of high-mass star formation regions
• APEX Millimeter Observations of Methanol Emission Toward High-Mass Star-Forming Cores
• A sensitive search for predicted methanol maser transitions with the Australia Telescope Compact Array