1,397 research outputs found
Extraterritorial Jurisdiction under the Proposed Federal Criminal Codes: Senate Bill 1630 and House Bill 1647
A photometric study of the hot exoplanet WASP-19b
Context: When the planet transits its host star, it is possible to measure
the planetary radius and (with radial velocity data) the planet mass. For the
study of planetary atmospheres, it is essential to obtain transit and
occultation measurements at multiple wavelengths.
Aims: We aim to characterize the transiting hot Jupiter WASP-19b by deriving
accurate and precise planetary parameters from a dedicated observing campaign
of transits and occultations.
Methods: We have obtained a total of 14 transit lightcurves in the r'-Gunn,
IC, z'-Gunn and I+z' filters and 10 occultation lightcurves in z'-Gunn using
EulerCam on the Euler-Swiss telescope and TRAPPIST. We have also obtained one
lightcurve through the narrow-band NB1190 filter of HAWK-I on the VLT measuring
an occultation at 1.19 micron. We have performed a global MCMC analysis of all
new data together with some archive data in order to refine the planetary
parameters and measure the occultation depths in z'-band and at 1.19 micron.
Results: We measure a planetary radius of R_p = 1.376 (+/-0.046) R_j, a
planetary mass of M_p = 1.165 (+/-0.068) M_j, and find a very low eccentricity
of e = 0.0077 (+/-0.0068), compatible with a circular orbit. We have detected
the z'-band occultation at 3 sigma significance and measure it to be dF_z'= 352
(+/-116) ppm, more than a factor of 2 smaller than previously published. The
occultation at 1.19 micron is only marginally constrained at dF_1190 = 1711
(+/-745) ppm.
Conclusions: We have shown that the detection of occultations in the visible
is within reach even for 1m class telescopes if a considerable number of
individual events are observed. Our results suggest an oxygen-dominated
atmosphere of WASP-19b, making the planet an interesting test case for
oxygen-rich planets without temperature inversion.Comment: Published in Astronomy & Astrophysics. 11 pages, 11 figures, 4 table
Recherche de la signification des différences de valeur nutritive observées entre feuilles de blé jeunes et âgées chez Locusta migratoria (R. et F.) (Orthoptera, Acrididae)
Influence du tégument des graines de Vicia faba sur le développement larvaire de Callosobruchus maculatus
An educated search for transiting habitable planets: (Research Note) Targetting M dwarfs with known transiting planets
Because the planets of a system form in a flattened disk, they are expected to share similar orbital inclinations at the end of their formation. The high-precision photometric monitoring of stars known to host a transiting planet could thus reveal the transits of one or more other planets. We investigate here the potential of this approach for the M dwarf GJ 1214 that hosts a transiting super-Earth. For this system, we infer the transit probabilities as a function of orbital periods. Using Monte-Carlo simulations we address both the cases for fully coplanar and for non-coplanar orbits, with three different choices of inclinations distribution for the non-coplanar case. GJ 1214 reveals to be a very promising target for the considered approach. Because of its small size, a ground-based photometric monitoring of this star could detect the transit of a habitable planet as small as the Earth, while a space-based monitoring could detect any transiting habitable planet down to the size of Mars. The mass measurement of such a small planet would be out of reach for current facilities, but we emphasize that a planet mass would not be needed to confirm the planetary nature of the transiting object. Furthermore, the radius measurement combined with theoretical arguments would help us to constrain the structure of the planet
Spin density distribution in a partially magnetized organic quantum magnet
Polarized neutron diffraction experiments on an organic magnetic material
reveal a highly skewed distribution of spin density within the magnetic
molecular unit. The very large magnitude of the observed effect is due to
quantum spin fluctuations. The data are in quantitative agreement with direct
diagonalization results for a model spin Hamiltonian, and provide insight on
the actual microscopic origin of the relevant exchange interactions.Comment: 5 pages 4 figure
Ground-based monitoring of comet 67P/Churyumov-Gerasimenko gas activity throughout the <i>Rosetta</i> mission
Simultaneously to the ESA Rosetta mission, a world-wide ground-based campaign provided measurements of the large scale activity of comet 67P/Churyumov-Gerasimenko through measurement of optically active gas species and imaging of the overall dust coma. We present more than two years of observations performed with the FORS2 low resolution spectrograph at the VLT, TRAPPIST, and ACAM at the WHT. We focus on the evolution of the CN production, as a tracer of the comet activity. We find that it is asymmetric with respect to perihelion and different from that of the dust. The CN emission is detected for the first time at 1.34 au pre-perihelion and production rates then increase steeply to peak about two weeks after perihelion at (1.00±0.10) ×1025 molecules s−1, while the post-perihelion decrease is more shallow. The evolution of the comet activity is strongly influenced by seasonal effects, with enhanced CN production when the Southern hemisphere is illuminated
The thermal emission of the young and massive planet CoRoT-2b at 4.5 and 8 microns
We report measurements of the thermal emission of the young and massive
planet CoRoT-2b at 4.5 and 8 microns with the Spitzer Infrared Array Camera
(IRAC). Our measured occultation depths are 0.510 +- 0.042 % and 0.41 +- 0.11 %
at 4.5 and 8 microns, respectively. In addition to the CoRoT optical
measurements, these planet/star flux ratios indicate a poor heat distribution
to the night side of the planet and are in better agreement with an atmosphere
free of temperature inversion layer. Still, the presence of such an inversion
is not definitely ruled out by the observations and a larger wavelength
coverage is required to remove the current ambiguity. Our global analysis of
CoRoT, Spitzer and ground-based data confirms the large mass and size of the
planet with slightly revised values (Mp = 3.47 +- 0.22 Mjup, Rp = 1.466 +-
0.044 Rjup). We find a small but significant offset in the timing of the
occultation when compared to a purely circular orbital solution, leading to e
cos(omega) = -0.00291 +- 0.00063 where e is the orbital eccentricity and omega
is the argument of periastron. Constraining the age of the system to be at most
of a few hundreds of Myr and assuming that the non-zero orbital eccentricity is
not due to a third undetected body, we model the coupled orbital-tidal
evolution of the system with various tidal Q values, core sizes and initial
orbital parameters. For log(Q_s') = 5 - 6, our modelling is able to explain the
large radius of CoRoT-2b if log(Q_p') <= 5.5 through a transient tidal
circularization and corresponding planet tidal heating event. Under this model,
the planet will reach its Roche limit within 20 Myr at most.Comment: 13 pages, 2 tables, 11 figures. Accepted for publication in Astronomy
and Astrophysic
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