text: 41,89,1113972053197983745,30989098,Karin Sandstrom,"Hey interstellar dust fans! Check out the new paper from UCSD postdoc Jérémy Chastenet on polycyclic aromatic hydrocarbons in the Magellanic Clouds! <LINK> The SMC is has a much smaller fraction of its dust in the form of PAHs compared to the LMC. <LINK> HII regions show up as holes in the PAH fraction map. Even ionized gas in the diffuse ISM seems to have an effect on the PAH population though. And when you separate the Magellanic Clouds up into their ISM phases, you find that the PAH fraction is largest in molecular/diffuse neutral gas and lowest in HII regions. @aprilfollies The lower PAH fraction seems to be related to whatever sources produce ionizing radiation to create the HII regions and diffuse ionized gas. @dr_paul_woods I don’t think we know for the MW very well, the 4.6% is for the diffuse neutral gas, not the global average. The comparison to full galaxy qpah values from SINGS suggests the LMC global average is pretty normal, but there are galaxies with higher path fractions.",https://arxiv.org/abs/1904.02705,"We present maps of the dust properties in the Small and Large Magellanic Clouds (SMC, LMC) from fitting Spitzer and Herschel observations with the \citet{DL07} dust model. We derive the abundance of the small carbonaceous grain (or polycyclic aromatic hydrocarbon; PAH) component. The global PAH fraction (q_pah, the fraction of the dust mass in the form of PAHs) is smaller in the SMC (1.0$^{+0.3}_{-0.3}$%) than in the LMC (3.3$^{+1.4}_{-1.3}$%). We measure the PAH fraction in different gas phases (H II regions, ionized gas outside of H II regions, molecular gas, and diffuse neutral gas). H II regions appear as distinctive holes in the spatial distribution of the PAH fraction. In both galaxies, the PAH fraction in the diffuse neutral medium is higher than in the ionized gas, but similar to the molecular gas. Even at equal radiation field intensity, the PAH fraction is lower in the ionized gas than in the diffuse neutral gas. We investigate the PAH life-cycle as a function of metallicity between the two galaxies. The PAH fraction in the diffuse neutral medium of the LMC is similar to that of the Milky Way ($\sim4.6$%), while it is significantly lower in the SMC. Plausible explanations for the higher PAH fraction in the diffuse neutral medium of the LMC compared to the SMC include: a more effective PAH production by fragmentation of large grains at higher metallicity, and/or the growth of PAHs in molecular gas. ","The Polycyclic Aromatic Hydrocarbon Mass Fraction on a 10 pc scale in