KICP Seminars & Colloquia 2020 2019 2018 2017 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 Fall Summer Spring Winter 2006 2005 2004 2003 2002 2001

KICP Seminars & Colloquia, Summer 2007 OPEN GROUP SEMINARS ASTRONOMY SPECIAL SEMINARS Seminar schedule for Summer 2007 June 26, 2007 Astronomy Special Seminar David Bennett University of Notre Dame Extrasolar Planets as a Blemish in Einstein's Telescope   [Abstract] August 10, 2007 Astronomy Special Seminar Eduard Vorobyov University of Western Ontario The burst mode of accretion in the early evolutionary phase of low-mass protostars   [Abstract] September 6, 2007 Open Group seminar Keith J B Grainge Cavendish Astyrophysics, Cambridge University AMI - The Arcminute Microkelvin Imager September 14, 2007 Open Group seminar Ramprasad Rao Submillimeter Array (ASIAA) Magnetic Field Observations of Star Forming Regions with the Submillimeter Array   [Abstract]   OPEN GROUP SEMINARS September 6, 2007 September 14, 2007 September 6, 2007 | 12:00 PM | LASR Conference Room | Open Group seminar AMI - The Arcminute Microkelvin Imager Keith J B Grainge, Cavendish Astyrophysics, Cambridge University September 14, 2007 | 12:00 PM | LASR Conference Room | Open Group seminar Magnetic Field Observations of Star Forming Regions with the Submillimeter Array Ramprasad Rao, Submillimeter Array (ASIAA) Magnetic fields are believed to play a crucial role in the star formation process. Observations of polarized dust emission from active star forming regions can be used to map the magnetic field. The Submillimeter Array (SMA) was used to obtain maps of the magnetic field in a number of Class 0 and Class I young stellar objects. I will be presenting and discussing some of these results. These observations by the SMA have been successful at providing new evidence that show that the effects of magnetic field are important in these objects.   ASTRONOMY SPECIAL SEMINARS June 26, 2007 August 10, 2007 June 26, 2007 | 12:00 PM | AAC 123 | Special Seminar Extrasolar Planets as a Blemish in Einstein's Telescope David Bennett, University of Notre Dame TBA August 10, 2007 | 1:00 PM | RI 180 | Special Seminar The burst mode of accretion in the early evolutionary phase of low-mass protostars Eduard Vorobyov, University of Western Ontario We present new numerical simulations in the thin-disk approximation which characterize the burst mode of protostellar accretion. The burst mode begins upon the formation of a centrifugally balanced disk around a newly formed protostar. It is comprised of prolonged quiescent periods of low accretion rate which are punctuated by intense bursts of accretion (typically ~ 10^{-4} Msun yr^{-1}), during which most of the protostellar mass is accumulated. The accretion bursts are associated with the formation of dense protoplanetary embryos, which are later driven onto the protostar by the gravitational torques that develop in the disk. Gravitational instability in the disk is driven by continuing infall from the cloud core envelope. We show that the disk mass always remains significantly less than the central protostar mass throughout this process. The burst phenomenon is robust enough to occur for a variety of initial values of rotation rate, frozen-in (supercritical) magnetic field, and density-temperature relations. Even in cases where the bursts are nearly entirely suppressed, a moderate increase in cloud size or rotation rate can lead to vigorous burst activity. We conclude that most (if not all) protostars undergo a burst mode of evolution during their early accretion history, as inferred empirically from observations of FU Orionis variables.