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Add to Calendar 3/13/2018 3:45 pm 3/13/2018 America/Chicago Astronomy Colloquium - "The Yin and Yang of Slowly-Pulsating B Stars: Asteroseismology and Angular Momentum Redistribution" DESCRIPTION:

During their main-sequence evolution, almost all B-type stars will pass through a phase where they are unstable toward oscillation in one or more global internal gravity waves ('g modes'). The g modes, driven by iron and nickel opacity in the stars' outer envelopes, generate surface temperature and velocity changes with periodicities on the order of days.

In the 'Yin' part of my talk, I'll discuss how time-series spectroscopy and photometry of these `slowly-pulsating B' (SPB) stars can be leveraged into asteroseismology --- probing the stars' interiors by careful analysis of their oscillation spectra. I'll highlight in particular how the Kepler mission, together with the MESA stellar evolution code and my GYRE stellar oscillation code, has allowed novel constraints to be established on the internal rotation and mixing physics of SPB stars.

I'll then pivot to the 'Yang' part of my talk. Although we typically regard stellar oscillations as passive tracers of stellar structure, they can also modify this structure. I'll present recent work by my group exploring angular momentum redistribution by g modes. Modeling this process in SPB stars, we find that significant modification of internal rotation profiles can occur on timescales as short as a few hundred years. This suggests that the g modes can impact the stars' life trajectories, a possibility that's been hitherto ignored in stellar evolution calculations.

\n\nSPEAKER:

Dr. Richard Townsend, University of Wisconsin

Astronomy 134

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Astronomy Colloquium - "The Yin and Yang of Slowly-Pulsating B Stars: Asteroseismology and Angular Momentum Redistribution"

Speaker Dr. Richard Townsend, University of Wisconsin
Date: 3/13/2018
Time: 3:45 p.m.
Location:

Astronomy 134

Event Contact: Rebecca Bare
217-333-3090
Sponsor:

Department of Astronomy

Event Type: Seminar/Symposium
 

During their main-sequence evolution, almost all B-type stars will pass through a phase where they are unstable toward oscillation in one or more global internal gravity waves ('g modes'). The g modes, driven by iron and nickel opacity in the stars' outer envelopes, generate surface temperature and velocity changes with periodicities on the order of days.

In the 'Yin' part of my talk, I'll discuss how time-series spectroscopy and photometry of these `slowly-pulsating B' (SPB) stars can be leveraged into asteroseismology --- probing the stars' interiors by careful analysis of their oscillation spectra. I'll highlight in particular how the Kepler mission, together with the MESA stellar evolution code and my GYRE stellar oscillation code, has allowed novel constraints to be established on the internal rotation and mixing physics of SPB stars.

I'll then pivot to the 'Yang' part of my talk. Although we typically regard stellar oscillations as passive tracers of stellar structure, they can also modify this structure. I'll present recent work by my group exploring angular momentum redistribution by g modes. Modeling this process in SPB stars, we find that significant modification of internal rotation profiles can occur on timescales as short as a few hundred years. This suggests that the g modes can impact the stars' life trajectories, a possibility that's been hitherto ignored in stellar evolution calculations.

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