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The nature of G52.381-0.849 and G56.240-0.345: young stellar objects associated with extended mid-infrared emission?

We report the results of visual spectroscopy, mid-infrared (MIR) mapping and photometry, and near-infrared photometry of two candidate symbiotic stars (IPHAS J193108.67+164950.5 and IPHAS J193709.65+202655.7) associated with extended MIR emission. Our analysis of the continua of these sources shows that they are likely to represent Class I-II young stellar objects (YSOs) in which most of the IR emission arises from circumstellar discs, and for which the physical characteristics (stellar temperatures, radii, masses and luminosities) are similar. The extended emission is characterized by a substantial increase in fluxes and dimensions to longer MIR wavelengths. This is likely to arise as a result of emission by polycyclic aromatic hydrocarbons within extended photodissociation regimes, centred upon more compact ionized regions responsible for much of the shorter wave emission. Such dual emission structures are characteristic of those observed in many compact HII regions. Finally, we note that the clouds have asymmetrical structures and wind-swept morphologies, conceivably indicative of shock interaction with external winds. Where this is the case, then it is possible that the YSOs are located in regions of triggered star formation.