Masers in GLIMPSE Extended Green Objects (EGOs)

Claudia J. Cyganowski, Crystal L. Brogan, Todd R. Hunter, Ed Churchwell, Jin Koda, Erik Rosolowsky, Sarah Towers, Barb Whitney, Qizhou Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Large-scale Spitzer surveys of the Galactic plane have yielded a new diagnostic for massive young stellar objects (MYSOs) that are actively accreting and driving outflows: extended emission in the IRAC 4.5 μmband, believed to trace shocked molecular gas. Maser studies of these extended 4.5 μm sources (called EGOs, Extended Green Objects, for the common coding of 3-color IRAC images) have been and remain crucial for understanding the nature of EGOs. High detection rates in VLA CH3OH maser surveys provided the first proof that EGOs were indeed MYSOs driving outflows; our recent Nobeyama 45-m survey of northern EGOs shows that the majority are associated with H2O masers. Maser studies of EGOs also provide important constraints for the longstanding goal of a maser evolutionary sequence for MYSOs, particularly in combination with high resolution (sub)mm data. New SMA results show that Class I methanol masers can be excited by both young (hot core) and evolved (ultracompact HII region) sources within the same massive star-forming region.
Original languageEnglish
Title of host publicationCosmic Masers -- from OH to H0
Subtitle of host publicationProceedings of the International Astronomical Union
Publication statusPublished - 1 Jul 2012


  • infrared: ISM- infrared: stars- ISM: jets and outflows- ISM: molecules- masers- radio continuum: ISM- stars: formation- techniques: interferometric


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