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New Techniques in Stellar Radial Velocity Characterization

skgrunblatt
February 20, 2015

New Techniques in Stellar Radial Velocity Characterization

Gaussian process models and time-distance helioseismology to analyze radial velocities taken of the Sun and other stars.

skgrunblatt

February 20, 2015
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  1. 699-1: Goal Create nonparametric model of stellar activity based only

    on data and astrophysical inference about stars. Will allow for better planetary Doppler signal extraction from RV measurements.
  2. Global Helioseismology Analysis of standing acoustic waves on solar surface.

    Does not require resolved images: similar to asteroseismology
  3. 699-2: Goal Account for systematics in T-D helioseismology due to

    solar atmosphere, and provide way to check for consistency. Empirically determine sunspot dynamics from robust travel time inversions.
  4. 699-2: Fit model to data y(t) = A2 ! p

    8⇡ exp " !2(t Tg)2 8 # cos[!(t Tp)] Gabor wavelet equation: A: amplitude ω: 2πν, ν=freq. δω: 2πδν Tg: group time of wave Tp: phase time of wave Least squares fit to data:
  5. Next steps Later: Measure localized variation in Doppler images of

    Sun. Extend GP model to account for local noise at various timescales with a more complex kernel function Sooner: Use empirically-measured sunspot dynamics to explain GP model parameters. Do starspots really decay the way we think they do?