2017AJ....154..201K

Arcuate infrared nebulae are ubiquitous throughout the Galactic Plane and are candidates for partial shells, bubbles, or bowshocks produced by massive runaway stars. We tabulate infrared photometry for 709 such objects using images from the Spitzer Space Telescope, the Wide-field Infrared Explorer, and the Herschel Space Observatory (HSO). Of the 709 objects identified at 24 or 22 µm, 422 are detected at the HSO 70 µm bandpass. Of these, only 39 are detected at HSO 160 µm. The 70 µm peak surface brightnesses are 0.5-2.5 Jy arcmin^–2. Color temperatures calculated from the 24 to 70 µm ratios range from 80 to 400 K. Color temperatures from 70 to 160 µm ratios are systematically lower, 40-200 K. Both of these temperature are, on average, 75% higher than the nominal temperatures derived by assuming that dust is in steady-state radiative equilibrium. This may be evidence of stellar wind bowshocks sweeping up and heating-possibly fragmenting but not destroying-interstellar dust. Infrared luminosity correlates with standoff distance, R₀, as predicted by published hydrodynamical models. Infrared spectral energy distributions are consistent with interstellar dust exposed to either single radiant energy density, U=10³–10⁵ (in more than half of the objects) or a range of radiant energy densities U_min = 25 to U_max = 10³-10⁵ times the mean interstellar value for the remainder. Hence, the central OB stars dominate the energetics, making these enticing laboratories for testing dust models in constrained radiation environments. The spectral energy densities are consistent with polycyclic aromatic hydrocarbon fractions q_PAH 1 % in most objects.