Series: Astronomy Colloquium
Date: Wednesday 07-Sep-2022
Time: 16:05-17:00 (4:05-5:00 pm)
Location: ATL 2400
Speaker: Dr. James Jackson (NRAO)
Title: The Radio Ammonia Mid-Plane Survey (RAMPS)
The Radio Ammonia Mid-Plane Survey used the K-band Focal Plane Array on the 100-m Green Bank Telescope to map the NH3 (1,1) through (5,5) inversion lines and H2O maser emission over 21.6 square degrees in the first quadrant of the Galactic Plane. The survey identified 2,680 dense molecular clumps in various evolutionary stages, from pre-stellar, to protostellar, to H II regions. A virial analysis of the clumps shows that the majority of clumps are unstable to gravitational collapse. Over 80% of pre-stellar and protostellar clumps have virial parameters < 0.5. The ensemble also shows kinematic evidence for collapse via the "blue” asymmetry of an optically thick tracer (13CO) with respect to an optically thin tracer (NH3). These clouds are so opaque that even 13CO is optically thick (typically tau~5). Finally, RAMPS data reveal unusual NH3 emission from the filamentary Infrared Dark Cloud G23.33-0.30. Toward this source, the NH3 linewidths are unusually broad (~25 km/s) and the NH3 (3,3) line reveals unusual maser emission. Follow up observations with the VLA and SMA indicate that this cloud is being struck by a supernova blast, which has heated, accelerated, and injected turbulence into a portion of the filament.
In-person colloquia are usually preceded by espresso and ice cream at 1:45 pm outside room PSC 1150 and are followed by an informal reception at 5:15 pm in that room. Anyone interested in talking with the speaker, or being added to the colloquium announcement email list, should contact the colloquium organizer Dr. Leslie Sage. Lunch will normally be reserved for the speaker to talk to graduate students. Anyone asking a question during a talk is asked to raise their hand and be acknowledged before speaking. Contact Dr. Leslie Sage for details.
Colloquium Organizer:
Dr. Leslie Sage
Special accommodations for individuals with disabilities can be made by calling (301) 405-3001. It would be appreciated if we are notified at least one week in advance.
