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