25 research outputs found
Refined Properties of the HD 130322 Planetary System
Exoplanetary systems closest to the Sun, with the brightest host stars,
provide the most favorable opportunities for characterization studies of the
host star and their planet(s). The Transit Ephemeris Refinement and Monitoring
Survey uses both new radial velocity measurements and photometry in order to
greatly improve planetary orbit uncertainties and the fundamental properties of
the star, in this case HD 130322. The only companion, HD 130322b, orbits in a
relatively circular orbit, e = 0.029 every ~10.7 days. Radial velocity
measurements from multiple sources, including 12 unpublished from the Keck I
telescope, over the course of ~14 years have reduced the uncertainty in the
transit midpoint to ~2 hours. The transit probability for the b-companion is
4.7%, where M_p sin i = 1.15 M_J and a = 0.0925 AU. In this paper, we compile
photometric data from the T11 0.8m Automated Photoelectric Telescope at
Fairborn Observatory taken over ~14 years, including the constrained transit
window, which results in a dispositive null result for both full transit
exclusion of HD 130322b to a depth of 0.017 mag and grazing transit exclusion
to a depth of ~0.001 mag. Our analysis of the starspot activity via the
photometric data reveals a highly accurate stellar rotation period: 26.53
+/-0.70 days. In addition, the brightness of the host with respect to the
comparison stars is anti-correlated with the Ca II H and K indices, typical for
a young solar-type star.Comment: 9 pages, 4 figures, 4 tables, accepted to Ap
The California Planet Survey IV: A Planet Orbiting the Giant Star HD 145934 and Updates to Seven Systems with Long-Period Planets
We present an update to seven stars with long-period planets or planetary
candidates using new and archival radial velocities from Keck-HIRES and
literature velocities from other telescopes. Our updated analysis better
constrains orbital parameters for these planets, four of which are known
multi-planet systems. HD 24040 b and HD 183263 c are super-Jupiters with
circular orbits and periods longer than 8 yr. We present a previously unseen
linear trend in the residuals of HD 66428 indicative on an additional planetary
companion. We confirm that GJ 849 is a multi-planet system and find a good
orbital solution for the c component: it is a planet in a 15 yr
orbit (the longest known for a planet orbiting an M dwarf). We update the HD
74156 double-planet system. We also announce the detection of HD 145934 b, a planet in a 7.5 yr orbit around a giant star. Two of our stars, HD
187123 and HD 217107, at present host the only known examples of systems
comprising a hot Jupiter and a planet with a well constrained period yr,
and with no evidence of giant planets in between. Our enlargement and
improvement of long-period planet parameters will aid future analysis of
origins, diversity, and evolution of planetary systems.Comment: 16 pages, 13 figures. Accepted for publication in Ap
A Comprehensive Characterization of the 70 Virgins Planetary System
An on-going effort in the characterization of exoplanetary systems is the accurate determination of host star properties. This effort extends to the relatively bright host stars of planets discovered with the radial velocity method. The Transit Ephemeris Refinement and Monitoring Survey (TERMS) is aiding in these efforts as part of its observational campaign for exoplanet host stars. One of the first known systems is that of 70 Virginis, which harbors a jovian planet in an eccentric orbit. Here we present a complete characterization of this system with a compilation of TERMS photometry, spectroscopy, and interferometry. We provide fundamental properties of the host star through direct interferometric measurements of the radius (1.5% uncertainty) and through spectroscopic analysis. We combined 59 new Keck HIRES radial velocity measurements with the 169 previously published from the ELODIE, Hamilton, and HIRES spectrographs, to calculate a refined orbital solution and construct a transit ephemeris for the planet. These newly determined system characteristics are used to describe the Habitable Zone of the system with a discussion of possible additional planets and related stability simulations. Finally, we present 19 years of precision robotic photometry that constrain stellar activity and rule out central planetary transits for a Jupiter-radius planet at the 5σ level, with reduced significance down to an impact parameter of b = 0.95
Eigenspectra: A Framework for Identifying Spectra from 3D Eclipse Mapping
Planetary atmospheres are inherently 3D objects that can have strong
gradients in latitude, longitude, and altitude. Secondary eclipse mapping is a
powerful way to map the 3D distribution of the atmosphere, but the data can
have large correlations and errors in the presence of photon and instrument
noise. We develop a technique to mitigate the large uncertainties of eclipse
maps by identifying a small number of dominant spectra to make them more
tractable for individual analysis via atmospheric retrieval. We use the
eigencurves method to infer a multi-wavelength map of a planet from
spectroscopic secondary eclipse light curves. We then apply a clustering
algorithm to the planet map to identify several regions with similar emergent
spectra. We combine the similar spectra together to construct an
"eigenspectrum" for each distinct region on the planetary map. We demonstrate
how this approach could be used to isolate hot from cold regions and/or regions
with different chemical compositions in observations of hot Jupiters with the
James Webb Space Telescope (JWST). We find that our method struggles to
identify sharp edges in maps with sudden discontinuities, but generally can be
used as a first step before a more physically motivated modeling approach to
determine the primary features observed on the planet.Comment: 13 pages, 17 figures, accepted to MNRA
Spitzer phase curve observations and circulation models of the inflated ultra-hot Jupiter WASP-76b
The large radii of many hot Jupiters can only be matched by models that have
hot interior adiabats, and recent theoretical work has shown that the interior
evolution of hot Jupiters has a significant impact on their atmospheric
structure. Due to its inflated radius, low gravity, and ultra-hot equilibrium
temperature, WASP-76b is an ideal case study for the impact of internal
evolution on observable properties. Hot interiors should most strongly affect
the non-irradiated side of the planet, and thus full phase curve observations
are critical to ascertain the effect of the interior on the atmospheres of hot
Jupiters. In this work, we present the first Spitzer phase curve observations
of WASP-76b. We find that WASP-76b has an ultra-hot day side and relatively
cold nightside with brightness temperatures of / at 3.6~\micron and / at 4.5~\micron, respectively. These results provide evidence
for a dayside thermal inversion. Both channels exhibit small phase offsets of
at 3.6~\micron and at
. We compare our observations to a suite of general
circulation models that consider two end-members of interior temperature along
with a broad range of frictional drag strengths. Strong frictional drag is
necessary to match the small phase offsets and cold nightside temperatures
observed. From our suite of cloud-free GCMs, we find that only cases with a
cold interior can reproduce the cold nightsides and large phase curve amplitude
at 4.5~\micron, hinting that the hot interior adiabat of WASP-76b does not
significantly impact its atmospheric dynamics or that clouds blanket its
nightside.Comment: 24 pages, 10 Figures, 5 Tables. Accepted to AJ. Co-First Author
Smaller than expected bright-spot offsets in Spitzer phase curves of the hot Jupiter Qatar-1b
We present \textit{Spitzer} full-orbit thermal phase curves of the hot
Jupiter Qatar-1b, a planet with the same equilibrium temperature---and
intermediate surface gravity and orbital period---as the well-studied planets
HD 209458b and WASP-43b. We measure secondary eclipse of at
m and at m, corresponding to dayside
brightness temperatures of ~K and ~K,
respectively, consistent with a vertically isothermal dayside. The respective
nightside brightness temperatures are ~K and
~K, in line with a trend that hot Jupiters all have similar
nightside temperatures. We infer a Bond albedo of and a
moderate day-night heat recirculation efficiency, similar to HD 209458b.
General circulation models for HD 209458b and WASP-43b predict that their
bright-spots should be shifted east of the substellar point by tens of degrees,
and these predictions were previously confirmed with \textit{Spitzer}
full-orbit phase curve observations. The phase curves of Qatar-1b are likewise
expected to exhibit eastward offsets. Instead, the observed phase curves are
consistent with no offset: at m and
at m. The discrepancy in circulation
patterns between these three otherwise similar planets points to the importance
of secondary parameters like rotation rate and surface gravity, and the
presence or absence of clouds, in determining atmospheric conditions on hot
Jupiters.Comment: 14 pages, 8 figures. Accepted for publication in A