1 28 Important for transits see next slides Transit depth R planet λ t R star λt 2 Not so important for eclipses because the eclipse is a simple difference and the stellar variability typically is slower than the eclipse ID: 411645
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Slide1
Effects of Stellar Variability:
1/28
Important for transits (see next slides).
Transit depth = [
R
planet
(
λ
,t
) /
R
star
(
λ,t
) ]
2
Not so important for eclipses because the eclipse is a simple difference, and the stellar variability typically is slower than the eclipse:
PLANET(t) = [ (STAR(t)+PLANET(t)) – STAR(t) ]
Can be very important for phase curves. How to disentangle?
Brighter stars are better. Poisson
Smaller stars are better. Contrast
Stable stars and stars with simpler spectra are better. InterpretationSlide2
2/28
Pont et al. (2013)Slide3
3/28Slide4
Stellar Spots?
4/28
HD 189733
K star
T
eff
= 5000 K
Correction required for
unocculted
spots:
Sum of spot areas ~5% or
~2x area of planet
Temperature of spots ~4000 K
Illustration shows two dominant spots, but it could be a few or many smaller ones, possibly in bands (see inset) or polar spot(s).Slide5
Pont et al. (2013)
Stellar Flux
1.02
1.00
0.98
Time (total ~ 6 years)Slide6
Planetary Rayleigh Scattering?
6/28
Effect on radius highly exaggerated.
Lecavelier
des
Estangs
et al. 2008
…
Pont et al. 2013
Pont et al. (2013)Slide7
McCullough et al. 2014
1.0% (open) and 1.7% (filled)
s
pot corrections were applied to ACS data