83 research outputs found
Near-infrared integral-field spectroscopy of HD209458b
We present first results of an exploratory study to use integral field
spectroscopy to observe extrasolar planets. We focus on transiting "Hot
Jupiters" and emphasize the importance of observing strategy and exact timing.
We demonstrate how integral field spectroscopy compares with other
spectroscopic techniques currently applied. We have tested our concept with a
time series observation of HD209458b obtained with SINFONI at the VLT during a
superior conjunction.Comment: SPIE conference proceeding, Astronomical telescopes and
instrumentation, Orlando, 200
A comprehensive study of Kepler phase curves and secondary eclipses -- temperatures and albedos of confirmed Kepler giant planets
We present a comprehensive study of phase curves and secondary eclipses in
the Kepler data set using all data from 16 quarters that were available in
2013-2014. Our sample consists of 20 confirmed planets with R_p > 4 R_e ,P <
10d, V_mag < 15. Here we derive their temperatures and albedos, with an eye
towards constraining models for the formation and evolution of such planets.
Where there was overlap our results confirm parameters derived by previous
studies, whereas we present new results for Kepler 1b-8b, 12b-15b, 17b, 40b,
41b, 43b, 44b, 76b, 77b, and 412b derived in a consistent manner. We also
present lightcurve analyses for Kepler 91b and Kepler 74b, which both show
extra dimmings at times other than from the expected primary and secondary
eclipses. Corrected for thermal emission we find most of the massive planets
from our sample to be low in albedo (<0.1) with a few having higher albedo
(>0.1).Comment: 50 pages, 7 figures - PASP accepte
EXONEST: Bayesian Model Selection Applied to the Detection and Characterization of Exoplanets Via Photometric Variations
EXONEST is an algorithm dedicated to detecting and characterizing the
photometric signatures of exoplanets, which include reflection and thermal
emission, Doppler boosting, and ellipsoidal variations. Using Bayesian
Inference, we can test between competing models that describe the data as well
as estimate model parameters. We demonstrate this approach by testing circular
versus eccentric planetary orbital models, as well as testing for the presence
or absence of four photometric effects. In addition to using Bayesian Model
Selection, a unique aspect of EXONEST is the capability to distinguish between
reflective and thermal contributions to the light curve. A case-study is
presented using Kepler data recorded from the transiting planet KOI-13b. By
considering only the non-transiting portions of the light curve, we demonstrate
that it is possible to estimate the photometrically-relevant model parameters
of KOI-13b. Furthermore, Bayesian model testing confirms that the orbit of
KOI-13b has a detectable eccentricity.Comment: Accepted for publication in The Astrophysical Journa
Combining Photometry From Kepler and TESS to Improve Short-Period Exoplanet Characterization
Planets emit thermal radiation and reflect incident light that they recieve
from their host stars. As a planet orbits it's host star the photometric
variations associated with these two effects produce very similar phase curves.
If observed through only a single bandpass this leads to a degeneracy between
certain planetary parameters that hinder the precise characterization of such
planets. However, observing the same planet through two different bandpasses
gives one much more information about the planet. Here, we develop a Bayesian
methodology for combining photometry from both \emph{Kepler} and the Transiting
Exoplanet Survey Satellite (TESS). In addition, we demonstrate via simulations
that one can disentangle the reflected and thermally emitted light from the
atmosphere of a hot-Jupiter as well as more precisely constrain both the
geometric albedo and dayside temperature of the planet. This methodology can
further be employed using various combinations of photometry from the James
Webb Space Telescope (JWST), the Characterizing ExOplanet Satellite (CHEOPS),
or the PLATO mission.Comment: Submitted to PAS
The Year-long Flux Variations in Boyajian's Star Are Asymmetric or Aperiodic
We combine and calibrate publicly available data for Boyajian's star, including photometry from ASAS (SN, V, I), Kepler, Gaia, SuperWASP, and citizen scientist observations (AAVSO, HAO, and Burke-Gaffney). Precise (mmag) photometry covers the years 2006–2017. We show that the year-long flux variations with an amplitude of ≈4% cannot be explained with cyclical symmetric or asymmetric models with periods shorter than 10 years. If the dips are transits, their periods must exceed 10 years, or their structure must evolve significantly during each four-year-long cycle
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