Time-Domain Astronomy with SOFIA: Results from Current Observations with FORCAST and Prospects with the Proposed New Instrument S3
Abstract
The most recent Decadal Review identified "time-domain astronomy" as an important frontier for astrophysical investigations. A key advantage to SOFIA in this realm is its 20+ year lifetime which allows long-term scientific studies that are not possible with space-based infrared missions alone. Here, we present two time-domain projects enabled by SOFIA's unique capabilities, one with current instrumentation - FORCAST, and the second with a proposed new instrument - S3. (1) The first project uses the FORCAST grism to obtain 5-37 µm spectra of carbon-rich post-AGB stars. Although most phases of stellar evolution take place on timescales of millions or billions of years, the post-asymptotic giant branch (post-AGB) phase, when a star rapidly transitions from a cool, dust-enshrouded object to a hot white dwarf illuminating a planetary nebula, lasts only ~1,000-10,000 years. Spectra from SOFIA's FORCAST instrument are enabling us to investigate the processes that occur during one of the most fleeting stages in a star's life. We compare these data to the mid-infrared spectra of the same objects obtained at ~10-15 year intervals over the past 35 years with Spitzer, ISO, and IRAS. (2) The second project will use a proposed new instrument, the high sensitivity, high spectral-resolution, heterodyne Submillimeter Spectrometer for SOFIA, S3. S3 is enabled by recent advances in detector technology, including improvements to digital backend spectrometers, low noise amplifiers, local oscillators, and closed cycle refrigerators. We will observe the line profiles of four carefully selected protoplanetary disks with S3 and their changes over the course of ~3 years. By repeatedly observing key transitions of ammonia and isotopic water in protoplanetary disks, we will trace the structure and composition of the disk to constrain the disk dynamics and planet formation models for each system we observe. These observations by S3 allow us to use Doppler tomography and similar techniques to kinematically image, for the first time, the *inner* regions of the planet-forming systems.
- Publication:
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American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23336409K