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"From Clouds to Planets: Stories from Herschel"

Dr. Joel Green
The Univ. of Texas at Austin, USA
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When: Tuesday, July 9, 2013 at 3:00 pm
Where: 2nd Floor Seminar Room

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Abstract:  

Protostars represent a key phase of star formation, after the collapse of a single core, tracing the assembly of the key materials (gas, ice, and dust) available for planet formation as the system contracts and irradiates its contents, prior to the complete unveiling of the system with the dispersal of the envelope.  The Herschel Space Observatory can see into the veiling envelope and surrounding cloud, probing key diagnostics - in particular, CO, OH, and water vapor, as well as crystalline silicate dust and continuum emission.  The DIGIT key program (PI: N. Evans), and complementary programs like FOOSH and COPS (PI: J. Green) have assembled a diverse sample of protostars with Herschel-PACS, SPIRE, and HIFI to answer the key question:  to what extent can we separate the system properties of a protostar (e.g. envelope/disk) from the extended properties (e.g. outflows, fast shocks)?   Because of its simple chemistry and high abundance, CO is an ideal tracer of such feedback, allowing us to separate the effects of outflow from envelope emission, while OH and H2O may trace differing layers of the envelope and disk, or contribute to cooling flows.  In addition to "standard" star forming modes, we observed a sample of outbursting young FU Orionis stars (rare episodic eruptors with dramatically raised accretion rates), to search for signposts of shocks.  I will present statistical trends, provide a general picture of the DIGIT sample, and begin to connect the observations with the detailed modeling efforts now ongoing.