NGC660 (z = 0.003) is a highly unusual Luminous Infra-Red Galaxy (LIRG) having a component that is strongly warped out of the plane of its main disc, plus an outer quasi-polar ring. An Arecibo spectral survey from 1.1 to 10 GHz was made in Nov-Dec, 2012, following the surprising discovery of excited-OH emission lines at 4750 and 4765 MHz in Dec 2008, which were not present in Dec 2007 and Aug 2008. These spectral features brightened between 2008 and 2012, with excited-OH absorption lines developing at 4660 MHz. All three transitions showed multiple components. A strong new continuum component had similar temporal development, and HSA-VLBI imaging of this show an outburst to be occurring in the nucleus of the galaxy. The new spectral survey used the Double Position Switching technique, with the Mock spectrometer as back-end. Interesting detections from the survey include multiple radio-recombination hydrogen lines, formaldehyde (H2CO) absorption at 4829 MHz, ground-state satellite OH lines at 1612 and 1720 that are conjugate, the satellite 6049-MHz excited-OH line, and the excited-CH line at 4848 MHz. Other possible detections, including apparent HCN (v2=1) emission at 4488 MHz, are being investigated.
American Astronomical Society Meeting Abstracts #223
- Pub Date:
- January 2014