Spectroscopic Orbits Of Kepler's Gas GiantsKOI-254: A Case Study
John A. JohnsonSebastian PinedaMichael Bottom
Zach GazakJosh WinnKevin Apps
Andrew HowardGeoff Marcy
Howard Isaacson
KOI-254
RP > 5 REarth
KOI-254• Cool: Teff < 4000 K (exact value very uncertain)• Faint: V = 16.9• R★ = 0.65 R, M★ = 0.53 M
• Period = 2.455 days• Transit Depth = 3.6%
Kepler
NickelLick Obs.
Johnson et al. 2011 in prep
RP = ??
??
Muirhead et al. (2011)
No Main Sequence!
Rojas Ayala et al. (2010)Rojas Ayala et al. (2011 in prep)
Muirhead et al. (2011)
On astro-ph NOW!
An Empirical Approach
• No reliance on atmosphere or evolution models
• Broadly applicable, without need for a parallax
A Photometric Calibration• J,H,K MJ,H,K M★, d (Delfosse et al. 2000)• V - K [Fe/H], M★ (Schlaufman & Laughlin 2010)• r - J MJ M★ (West et al. 2005, Delfosse et al.)• a/R★ M★ (Seager, Mallen-Ornelas 2003)
An example: K-band magnitude to Mass, distance
Johnson, Gazak, Apps et al. 2011 in prep
Sample of nearby stars with known parallaxes, and hence known M★
Johnson, Gazak, Apps et al. 2011 in prep
Why not optical spectroscopy?
Keck ObservatoryKeck Observatory400 Massive, Evolved Stars900 Sun-like dwarfs150 Low-mass M dwarfs with an average of 25 observations per star
50 individual spectra
Final coadded spectrum
M★ = 0.68 M 0.45 M 0.25 M
DecreasingMass
Pseudo- continuum
line region
Increasing Mass
Bottom, Pineda & Johnson 2011 in prep
Decreasing [Fe/H]
Bottom, Pineda & Johnson 2011 in prep
Bottom, Pineda & Johnson 2011 in prep
rms = 8.4%
Photometric
Spectroscopic
x
Parameter Photometric Spectroscopic
M★ (M) 0.57 ± 0.07 0.63 ± 0.04
R★ (R) 0.59 ± 0.08 0.65 ± 0.05
[Fe/H] +0.25 ± 0.12 +0.16 ± 0.15
Distance (pc) 350 ± 25 380 ± 15
MP (Mjup) 0.51 ± 0.06 0.54 ± 0.04
RP (Rjup) 1.00 ± 0.13 1.10 ± 0.08
Schlaufman & Laughlin (2010)Johnson & Apps (2009)
KOI-254b
Thank You
Sebastian PinedaMichael Bottom
Kevin AppsZach GazakJosh Winn
Andrew HowardGeoff Marcy
Howard Isaacson