Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.mrao.cam.ac.uk/wp-content/uploads/2014/04/RAngus.pdf Дата изменения: Wed Apr 16 17:16:53 2014 Дата индексирования: Sun Apr 10 13:26:44 2016 Кодировка: Поисковые слова: http astrokuban.info astrokuban

@ruthangus



Calibrating Gyrochronology with Kepler Asteroseismic targets

Ruth Angus, S. Aigrain, A. McQuillan, D. Foreman-Mackey, W. Chaplin, T. Mazeh




Ages of Planetary Systems
Tidal evolution:
- CoRoT 16b, HAT-P-2b = eccentric giant planets - Eccentricity damped out over long time-scales - Require knowledge of the system's age to understand tidal evolution

Obliquity evolution:
- Obliquity increases with age?

HZ Increasing age

Habitable zone evolution:
- HZs shift outwards

Ruth Angus, Oxford University


Irwin & Bouvier (2009)

Ruth Angus, Oxford University


Period-Age-Colour Plane
P vs t for Sun-like stars from Hyades to Sun (Skumanich 1972)

P vs B-V for Hyades (Kawaler 1988, Barnes 2007)
Ruth Angus, Oxford University


Rotation Period Measurement via Auto-Correlation
505 stars with asteroseismic ages from Chaplin et al (2013)


McQuillan, Aigrain & Mazeh (2013)
Ruth Angus, Oxford University


Comparison with current relations

Ruth Angus, Oxford University


Period vs Temperature

Ruth Angus, Oxford University


Period vs Temperature

Ruth Angus, Oxford University


Period vs Temperature

Ruth Angus, Oxford University


Period vs Temperature

Ruth Angus, Oxford University


Period vs Temperature

Ruth Angus, Oxford University


Period vs Temperature

Ruth Angus, Oxford University


Period vs Temperature

Ruth Angus, Oxford University


Fitting The Model
A=
P (T
k

T)

T < Tk (~6250) T > Tk

A = age, P = rotation period, T = effective temperature

Accounting for uncertainties on all variables:

Hogg, Myers & Bovy (2010)

Ruth Angus, Oxford University


PRELIMINARY results

Ruth Angus, Oxford University


Aside: Measuring Rotation with Gaussian Processes
kij = Ae

sin2 ( (xi xj )/P 2 l2 1

)

(xi

xj )2 2 l2 2

Ruth Angus, Oxford University


Aside: Measuring Rotation with Gaussian Processes
Quasi-periodic

Ruth Angus, Oxford University


Conclusions + Future work
· Rotation periods over-predicted by current gyro relations.
­ Instrinsic scatter?



· Complete modelling process

­ 2 or 3 populations. How complex do we want to go?

· Need better constraints on ages from asteroseismology. · Incorporate results from the Kepler cluster study (Meibom et al, in prep). · Would like to add low mass stars with longer periods to our sample.
­ K2 and Tess ­ Gaussian process rotation ­ Better detrending

Ruth Angus, Oxford University