List of Past CTC Theory Lunches : 01-Jan-2008 to 01-Jun-2008

Date:   Monday 04-Feb-2008
Speaker:   Eve Ostriker (STScI)
Title:  An overview of "Theory of star formation", Part I


This is part 1 of a 2 part presentation. Part 2 is at 4pm on Tuesday, Feb 5th (the following day), at the LMA seminar.


The seminars will provide a guide to contemporary understanding of star formation, outlining current theory and the observations that motivate it. A conception of star formation has emerged in which turbulence plays a dual role, both creating overdensities to initiate gravitational contraction or collapse, and countering the effects of gravity in these overdense regions. The key dynamical processes involved in star formation -- turbulence, magnetic fields, and self-gravity -- are highly nonlinear and multidimensional. Physical arguments are used to identify and explain the features and scalings involved in star formation, and results from numerical simulations are used to quantify these effects. After a discussion of basic physical processes, star formation on small scales and large scales will be reviewed in turn. The issues covered will include how cores form and evolve within giant molecular clouds (GMCs), and how GMCs themselves form and evolve within spiral galaxies. Important problems includes what determines the initial mass function of stars, and what determines the overall star formation rate. Although outstanding questions remain, the framework is now in place to build a comprehensive theory of star formation.

The talks will be based on my 2007 ARAA review with Chris McKee.

Date:   Monday 25-Feb-2008
Speaker:   Cole Miller and Tamara Bogdanovic
Title:   Summary of the LISA meeting in Como,Italy

Date:   Thursday 06-Mar-2008
Speaker:   Jason Steffen (Fermilab center for particle astrophysics)
Title:  Extrasolar planet detection via transit timing variations

I present a planet detection technique that is capable of probing for planets with masses less than the Earth using modest, ground-based telescopes. In a multiple planet system where one planet transits the host star, dynamical interactions among the various bodies cause the time interval between transits to vary. These variations are often quite large, particularly for systems in mean-motion resonance, and can be used to infer the orbital elements of the perturbing body. I discuss the essential aspects of this planet detection technique, its potential for additional discoveries with ongoing and planned transit surveys, its anticipated impact on planet formation and evolution theories, and the results of its application to two planetary systems. These results are the first to probe for planets with masses less than the Earth in orbit about Sun-like stars.

Date:   Monday 24-Mar-2008
Speaker:   Hiroshi Koyama
Title:   Gravitational collapse and fragmentation

Date:   Monday 31-Mar-2008
Speaker:   Alberto Bolatto
Title:   Extragalactic GMC properties

Date:   Monday 07-Apr-2008
Speaker:   Mike Gill
Title:   Using mass segregation to look for IMBHs in star clusters

Date:   Monday 21-Apr-2008
Speaker:   Alberto Sesana (Penn. State University)
Title:  The impact of seed black hole formation scenarios and of extreme GW recoil on LISA detections.

Abstract: The nature and abundance of the first seeds of the massive black holes we see today in galactic nuclei leave a unique imprint on the detection of gravitational waves at mHz frequencies. After a short introduction about massive black hole formation and gravitational wave detection, I will discuss the possibility of constraining different models of black hole formation and cosmic evolution using LISA, assessing its capability of providing unique high-redshift informations difficult to obtain by other means. I will also discuss the implications of extreme gravitational recoil for massive black hole binary demography, showing that this would not be a serious issue for LISA detections. In our worst (from the LISA detection point of view) scenario, we predict at least a dozen of sources to be safe LISA targets assuming a three year mission lifetime.

Date:   Monday 28-Apr-2008
Speaker:   Vanessa Lauburg
Title:   Prospects for LIGO Detection of Stellar-Mass Black Hole Binary Mergers in Galactic Nuclei

Date:   Monday 12-May-2008
Speaker:   Doug Hamilton
Title:   Jupiter's Ring System

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