211,321 research outputs found
A determination of the spin-orbit alignment of the anomalously dense planet orbiting HD 149026
We report 35 radial velocity measurements of HD 149026 taken with the Keck Telescope. Of these measurements, 15
were made during the transit of the companion planet HD 149026b, which occurred on 2005 June 25. These velocities
provide a high-cadence observation of the Rossiter-McLaughlin effect, the shifting of photospheric line profiles that occurs when a planet occults a portion of the rotating stellar surface. We combine these radial velocities with previously published radial velocity and photometric data sets and derive a composite best-fit model for the star-planet system. This model confirms and improves previously published orbital parameters, including the remarkably small planetary radius, the planetary mass, and the orbital inclination, found to be Rp/RJup = 0.718 ± 0.065, Mp/MJup = 0.352 ± 0.025, and I = 86.1° ± 1.4°, respectively. Together the planetary mass and radius determinations imply a mean planetary density
of 1.18(-0.30)(+0.38)g cm(-3). The new data also allow for the determination of the angle between the apparent stellar equator and the orbital plane, which we constrain to be λ = -12° ± 15°
Phase Curves of the Kepler-11 Multi-Planet System
The Kepler mission has allowed the detection of numerous multi-planet
exosystems where the planetary orbits are relatively compact. The first such
system detected was Kepler-11 which has six known planets at the present time.
These kinds of systems offer unique opportunities to study constraints on
planetary albedos by taking advantage of both the precision timing and
photometry provided by Kepler data to monitor possible phase variations. Here
we present a case study of the Kepler-11 system in which we investigate the
phase modulation of the system as the planets orbit the host star. We provide
predictions of maximum phase modulation where the planets are simultaneously
close to superior conjunction. We use corrected Kepler data for Q1-Q17 to
determine the significance of these phase peaks. We find that data quarters
where maximum phase peaks occur are better fit by a phase model than a "null
hypothesis" model.Comment: 9 pages, 4 figures, 2 tables, accepted for publication in Ap
Goldstone solar system radar signal processing
A performance analysis of the planetary radar data acquisition system is presented. These results extend previous computer simulation analysis and are facilitated by the development of a simple analytical model that predicts radar system performance over a wide range of operational parameters. The results of this study are useful to both the radar system designer and the science investigator in establishing operational radar data acquisition parameters which result in the best systems performance for a given set of input conditions
A Bayesian Analysis of HAT-P-7b Using the EXONEST Algorithm
The study of exoplanets (planets orbiting other stars) is revolutionizing the
way we view our universe. High-precision photometric data provided by the
Kepler Space Telescope (Kepler) enables not only the detection of such planets,
but also their characterization. This presents a unique opportunity to apply
Bayesian methods to better characterize the multitude of previously confirmed
exoplanets. This paper focuses on applying the EXONEST algorithm to
characterize the transiting short-period-hot-Jupiter, HAT-P-7b. EXONEST
evaluates a suite of exoplanet photometric models by applying Bayesian Model
Selection, which is implemented with the MultiNest algorithm. These models take
into account planetary effects, such as reflected light and thermal emissions,
as well as the effect of the planetary motion on the host star, such as Doppler
beaming, or boosting, of light from the reflex motion of the host star, and
photometric variations due to the planet-induced ellipsoidal shape of the host
star. By calculating model evidences, one can determine which model best
describes the observed data, thus identifying which effects dominate the
planetary system. Presented are parameter estimates and model evidences for
HAT-P-7b.Comment: Submitted to the conference proceedings for MaxEnt 2014, to be
published by AI
Constraints on the location of a possible 9th planet derived from the Cassini data
To explain the unusual distribution of Kuiper Belt objects, several authors
have advocated the existence of a super-Earth planet in the outer solar system.
It has recently been proposed that a 10 M object with an orbit of
700 AU semi major axis and 0.6 eccentricity can explain the observed
distribution of Kuiper Belt objects around Sedna. Here we use the INPOP
planetary ephemerides model as a sensor for testing for an additional body in
the solar system. We test the possibility of adding the proposed planet without
increasing the residuals of the planetary ephemerides, fitted over the whole
INPOP planetary data sample. We demonstrate that the presence of such an object
is not compatible with the most sensitive data set, the Cassini radio ranging
data, if its true anomaly is in the intervals or
. Moreover, we find that the addition of this object
can reduce the Cassini residuals, with a most probable position given by a true
anomaly .Comment: Accepted for publication in A&A; 4 pages, 6 figure
Solar system constraints on the Dvali-Gabadadze-Porrati braneworld theory of gravity
A number of proposals have been put forward to account for the observed
accelerating expansion of the Universe through modifications of gravity. One
specific scenario, Dvali-Gabadadze-Porrati (DGP) gravity, gives rise to a
potentially observable anomaly in the solar system: all planets would exhibit a
common anomalous precession, dw/dt, in excess of the prediction of General
Relativity. We have used the Planetary Ephemeris Program (PEP) along with
planetary radar and radio tracking data to set a constraint of |dw/dt| < 0.02
arcseconds per century on the presence of any such common precession. This
sensitivity falls short of that needed to detect the estimated universal
precession of |dw/dt| = 5e-4 arcseconds per century expected in the DGP
scenario. We discuss the fact that ranging data between objects that orbit in a
common plane cannot constrain the DGP scenario. It is only through the relative
inclinations of the planetary orbital planes that solar system ranging data
have sensitivity to the DGP-like effect of universal precession. In addition,
we illustrate the importance of performing a numerical evaluation of the
sensitivity of the data set and model to any perturbative precession.Comment: 9 pages, 2 figures, accepted for publication in Phys. Rev.
Confirmation of the Planetary Microlensing Signal and Star and Planet Mass Determinations for Event OGLE-2005-BLG-169
We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3)
observations of the source and lens stars for planetary microlensing event
OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to
the planetary light curve signal observed for this event. This (and the
companion Keck result) provide the first confirmation of a planetary
microlensing signal, for which the deviation was only 2%. The follow-up
observations determine the flux of the planetary host star in multiple
passbands and remove light curve model ambiguity caused by sparse sampling of
part of the light curve. This leads to a precise determination of the
properties of the OGLE-2005-BLG-169Lb planetary system. Combining the
constraints from the microlensing light curve with the photometry and
astrometry of the HST/WFC3 data, we find star and planet masses of M_* = 0.69+-
0.02 M_solar and m_p = 14.1 +- 0.9 M_earth. The planetary microlens system is
located toward the Galactic bulge at a distance of D_L = 4.1 +- 0.4 kpc, and
the projected star-planet separation is a_perp = 3.5 +- 0.3 AU, corresponding
to a semi-major axis of a = 4.0 (+2.2 -0.6) AU.Comment: 21 pages, including 5 figures, published in Ap
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