From AGB Stars to Aspherical Planetary Nebulae: Recent Observational Highlights from the Far-IR and (Sub)mm to X-Rays – Part 2
Most stars that leave the main sequence in a Hubble time will end their lives, evolving through the Asymptotic Giant Branch (AGB), Preplanetary Nebula (PPN) and Planetary Nebula (PN) evolutionary phases.
We conduct a SOFIA FORCAST survey of bright, nearby star-forming clusters. The survey is focused on cores with sources that saturate Spitzer at 24 microns and WISE at 22 microns. The Young Stellar Object (YSO) population of these regions is explored thanks to SOFIA’s high angular resolution at 11.1, 19.7, 31.5 and 37.1 microns. We find ~70 sources, and among them, ~16 were previously unidentified or misidentified by Spitzer or WISE due to saturation or lack of angular resolution: we provide the first far-IR fluxes for these bright and/or clustered sources.
The infrared (IR) spectra of objects associated with dust and gas – including evolved stars, reflection nebulae, the interstellar medium (ISM), star-forming regions, and galaxies out to redshifts of z ∼ 3 – are dominated by emission bands at 3.3, 6.2, 7.7, 8.6 and 11.2 μm, the so-called unidentified infrared (UIR) bands. They are generally attributed to the IR fluorescence of Polycyclic Aromatic Hydrocarbon molecules (PAHs) UV pumped by nearby massive stars.
We present SOFIA/GREAT observations of [CII] 158 µm and [NII] 205µm emission from the nuclear region of the spiral IC 342. The [CII] and [NII] data will be used to characterize how much the different phases of the circum-nuclear ISM contributes relatively to the overall observed emission. Particularly the correlation between [NII], emitted from [HII] regions exclusively, and the [CII] emission line, coming both from PDRs and from the ionized gas, is studied taking advantage of the high spectral resolution of the [NII] and [CII] emission.
The ATLASGAL survey revealed in an unbiased way the population of massive clumps in the inner Galaxy, covering a large range of evolutionary stages. Here I will briefly describe the survey and then describe its molecular line follow-up projects, in particular SOFIA observations. New results from the SOFIA program to search for infall towards massive clumps using ammonia will be given and discussed.