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Hunting exoplanet
Astro 193 final project presentation Xiawei Wang 05/06/2015


Data
· Data set taken from Johnson et al., 2010, ApJL, 721, L153 · Keck data of radial velocity measurement of subgiant HD 102956 · Detection of a giant planet orbiting around it.
Large excursions


Orbital period
· We hot · We · P ~ use Lomb Scargle algorithm to find the orbital period of the Jupiter. use bootstrap to estimate peak significance. 6.495 days or f ~0.154 cycles/day
Jag ged pattern. Peaks of signals?


Spectral window
1 day

1 month

1 year

Alias

Discretely sampling a continuous signal
(Dawson & Fabrycky 10)


Radial velocity profile fit
· We assume a circular planetary orbit, then the planet's motion can be described as har monic:
· V(t|P) = Asin(t)+Bcos(t)+ · Parameter space: P={A, B, , } · accounts for systematic velocity

· We use MCMC to fit the parameters A, B, , · emcee algorithm (Foreman-Mackey et al., 2013, PASP, 125, 306):
· MCMC Hammer! · Implementation of Affine Invariant MCMC Ensemble sampler · Not sensitive to correlations between parameters


Radial velocity profile fit


Radial velocity profile fit


Summary
· Radial velocity data from Keck indicating a hot Jupiter in orbit around a subgiant · Lomb-Scargle algorithm to deter mine the orbital period · Bootstrap to find the peak significance of the periodogram · Aliasing rises as a result of discretely sampling of a continuous signal · MCMC to fit radial velocity profile parameters


Thank you!