Characterisation of gravity and Rossby modes in hundreds of Kepler γ Doradus stars

We present our analysis of ∼450 Kepler γ Doradus stars. These stars are pulsating mainly in gravity modes, but the periods are no longer equally-spaced due to core rotation and molecular weight gradients. So far we have discovered ∼600 period spacing patterns from ∼450 stars. These results constitute the largest γ Dor sample thus it is possible to reveal some new statistical relations. For dozens of slowly-rotating stars, we show how rotation distorts the asymptotic relation. In rapid rotators, we find that g-mode period spacings and their gradient (slope) are both positively correlated with period. Additionally, Rossby modes are seen in tens of stars. They have a negative correlation between the slope and mean period, which is twice the mean period of prograde gravity modes.  These stars are very useful for understanding the physics of rotation and angular momentum transport in main sequence stars, and can place much needed constraints on diffusive mixing and chemical gradients, whilst also providing stellar ages. As this is first sample with significant Rossby modes, we have the unprecedented opportunity to study these unfamiliar modes, like their instability strip, excitation mechanism and surface rotation.

Speaker: 
Gang LI
Location: 
first floor meeting room, KIAA
Time: 
Tue, 2018-08-07 12:00 to 13:00