Johanna K. Teske

197 CANDIDATES AND 104 VALIDATED PLANETS IN K2's FIRST FIVE FIELDS

NASA through the Sagan Fellowship Program; NASA through a Hubble Fellowship - Space Telescope Science Institute; NASA [NAS 5-26555, NNH14CK55B]; National Science Foundation Graduate Research Fellowship [2014184874]; FONDECYT [1130857]; BASAL CATA [PFB-06]; Ministry for the Economy, Development, and Tourisms Programa Iniciativa Cientifica Milenio [IC 120009]; Alfred P. Sloan Foundation; National Science Foundation [AST-0906060, AST-0960343, AST-1207891]; Mt. Cuba Astronomical Foundation; Max Planck Institute for Astronomy; Heidelberg; Max Planck Institute for Extraterrestrial Physics, Garching; Johns Hopkins University; Durham University; University of Edinburgh; Queens University Belfast; Harvard-Smithsonian Center for Astrophysics; Las Cumbres Observatory Global Telescope Network Incorporated; National Central University of Taiwan; Space Telescope Science Institute; National Aeronautics and Space Administration [NNX08AR22G]; University of Maryland; Eotvos Lorand University (ELTE)

Optical observations of the transiting exoplanet GJ 1214b

We observed nine primary transits of the super-Earth exoplanet GJ 1214b in several optical photometric bands from 2012 March to August, with the goal of constraining the shortwavelength slope of the spectrum of GJ 1214b. Our observations were conducted on the Kuiper 1.55 m telescope in Arizona and the STELLA-I robotic 1.2 m telescope in Tenerife, Spain. From the derived light curves we extracted transit depths in R (0.65µm), V (0.55µm) and g � (0.475µm) bands. Most previous observations of this exoplanet suggest a flat spectrum varying little with wavelength from the near-infrared to the optical, corresponding to a lowscale height, high-molecular-weight atmosphere. However, a handful of observations around Ks band (∼2.15µm) and g band (∼0.46µm) are inconsistent with this scenario and suggest a variation on a hydrogen- or water-dominated atmosphere that also contains a haze layer of small particles. In particular, the g-band observations of de Mooij et al., consistent with Rayleigh scattering, limit the potential atmosphere compositions of GJ 1214b due to the increasing slope at optical wavelengths. We find that our results overlap within errors the short-wavelength observations of de Mooij et al., but are also consistent with a spectral slope of zero in GJ 1214b in the optical wavelength region. Our observations thus allow for a larger suite of possible atmosphere compositions, including those with a high molecular weight and/or hazes.

Carbon and Oxygen Abundances in Cool Metal-rich Exoplanet Hosts: A Case Study of the C/O Ratio of 55 Cancri

The super-Earth exoplanet 55 Cnc e, the smallest member of a five-planet system, has recently been observed to transit its host star. The radius estimates from transit observations, coupled with spectroscopic determinations of mass, provide constraints on its interior composition. The composition of exoplanetary interiors and atmospheres are particularly sensitive to elemental C/O ratio, which to first order can be estimated from the host stars. Results from a recent spectroscopic study analyzing the 6300A [O I] line and two C I lines suggest that 55 Cnc has a carbon-rich composition (C/O=1.12+/-0.09). However oxygen abundances derived using the 6300A [O I] line are highly sensitive to a Ni I blend, particularly in metal-rich stars such as 55 Cnc ([Fe/H]=0.34+/-0.18). Here, we further investigate 55 Cncs composition by deriving the carbon and oxygen abundances from these and additional C and O absorption features. We find that the measured C/O ratio depends on the oxygen lines used. The C/O ratio that we derive based on the 6300A [O I] line alone is consistent with the previous value. Yet, our investigation of additional abundance indicators results in a mean C/O ratio of 0.78+/-0.08. The lower C/O ratio of 55 Cnc determined here may place this system at the sensitive boundary between protoplanetary disk compositions giving rise to planets with high (>0.8) versus low (<0.8) C/O ratios. This study illustrates the caution that must applied when determining planet host star C/O ratios, particularly in cool, metal-rich stars.

Abundance Differences between Exoplanet Binary Host Stars XO-2N and XO-2S?Dependence on Stellar Parameters

The chemical composition of exoplanet host stars is an important factor in understanding the formation and characteristics of their orbiting planets. The best example of this to date is the planet-metallicity correlation. Other proposed correlations are thus far less robust, in part due to uncertainty in the chemical history of stars pre- and post-planet formation. Binary host stars of similar type present an opportunity to isolate the effects of planets on host star abundances. Here we present a differential elemental abundance analysis of the XO-2 stellar binary, in which both G9 stars host giant planets, one of which is transiting. Building on our previous work, we report 16 elemental abundances and compare the

The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey

\Delta

Ground-based near-UV observations of 15 transiting exoplanets: constraints on their atmospheres and no evidence for asymmetrical transits

(XO-2N-XO-S) values to elemental condensation temperatures. The

SIX PLANETS ORBITING HD 219134

\Delta

THE LICK-CARNEGIE EXOPLANET SURVEY: HD 32963—A NEW JUPITER ANALOG ORBITING A SUN-LIKE STAR

(N-S) values and slopes with condensation temperature resulting from four different pairs of stellar parameters are compared to explore the effects of changing the relative temperature and gravity of the stars. We find that most of the abundance differences between the stars depend on the chosen stellar parameters, but that Fe, Si, and potentially Ni are consistently enhanced in XO-2N regardless of the chosen stellar parameters. This study emphasizes the power of binary host star abundance analysis for probing the effects of giant planet formation, but also illustrates the potentially large uncertainties in abundance differences and slopes induced by changes in stellar temperature and gravity.

THE CURIOUS CASE OF ELEMENTAL ABUNDANCE DIFFERENCES IN THE DUAL HOT JUPITER HOSTS WASP-94A AND B*

This document is the Accepted Manuscript version of the following article: R. Paul Butler, et al, The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey, The Astronomical Journal, Vol 153 (5), 19 pp., published 13 April 2017. The Version of Record is available online at doi: https://doi.org/10.3847/1538-3881/aa66ca. Paper data available at: http://home.dtm.ciw.edu/ebps/data/.

Carbon and Oxygen Abundances in the Hot Jupiter Exoplanet Host Star XO-2B and Its Binary Companion

NASAs Planetary Atmospheres programme; Virginia Space Grant Consortium Graduate Research Fellowship Program; National Science Foundation [DGE-1315231]; University of Arizona Astronomy Club; Steward Observatory TAC; Lunar and Planetary Laboratory