3,912 research outputs found
On homogeneous statistical distributions exoplanets for their dynamic parameters
Correct distributions of extrasolar systems for their orbital parameters
(semi-major axes, period, eccentricity) and physical characteristics (mass,
spectral type of parent star) are received. Orbital resonances in extrasolar
systems are considered. It is shown, that the account of more thin effects,
including with use of wavelet methods, in obviously incorrectly reduced
distributions it is not justified, to what the homogeneous statistical
distributions for dynamic parameters of exoplanets, received in the present
work, testify.Comment: 9 pages, 15 figures; International Conference "100 years since
Tunguska phenomenon: Past, present and future", (June 26-28, 2008. Russia,
Moscow), Lomonosov readings 2009 (Moscow State University
z'-band Ground-Based Detection of the Secondary Eclipse of WASP-19b
We present the ground-based detection of the secondary eclipse of the
transiting exoplanet WASP-19b. The observations were made in the Sloan z'-band
using the ULTRACAM triple-beam CCD camera mounted on the NTT. The measurement
shows a 0.088\pm0.019% eclipse depth, matching previous predictions based on H-
and K-band measurements. We discuss in detail our approach to the removal of
errors arising due to systematics in the data set, in addition to fitting a
model transit to our data. This fit returns an eclipse centre, T0, of
2455578.7676 HJD, consistent with a circular orbit. Our measurement of the
secondary eclipse depth is also compared to model atmospheres of WASP-19b, and
is found to be consistent with previous measurements at longer wavelengths for
the model atmospheres we investigated.Comment: 20 pages, 10 figures. Published in the ApJ Supplement serie
The Swift view of Supergiant Fast X-ray Transients
We report here on the recent results of a monitoring campaign we have been
carrying out with Swift/XRT on a sample of four Supergiant Fast X-ray
Transients. The main goal of this large programme (with a net Swift/XRT
exposure of 540 ks, updated to 2009, August, 31) is to address several main
open issues related to this new class of High Mass X-ray Binaries hosting OB
supergiant stars as companions. Here we summarize the most important results
obtained between October 2007 and August 2009.Comment: Published on the Proceedings of the conference X-Ray Astronomy 2009,
Present Status, multiwavelenght approach and future perspectives, September 7
- 11, 2009, Bologna, Italy. Revised version according to the referee's repor
A Spitzer Spectrum of the Exoplanet HD 189733b
We report on the measurement of the 7.5-14.7 micron spectrum for the
transiting extrasolar giant planet HD 189733b using the Infrared Spectrograph
on the Spitzer Space Telescope. Though the observations comprise only 12 hours
of telescope time, the continuum is well measured and has a flux ranging from
0.6 mJy to 1.8 mJy over the wavelength range, or 0.49 +/- 0.02% of the flux of
the parent star. The variation in the measured fractional flux is very nearly
flat over the entire wavelength range and shows no indication of significant
absorption by water or methane, in contrast with the predictions of most
atmospheric models. Models with strong day/night differences appear to be
disfavored by the data, suggesting that heat redistribution to the night side
of the planet is highly efficient.Comment: 12 pages, 3 figures, accepted for publication in the Astrophysical
Journal Letter
A Two-Dimensional MagnetoHydrodynamics Scheme for General Unstructured Grids
We report a new finite-difference scheme for two-dimensional
magnetohydrodynamics (MHD) simulations, with and without rotation, in
unstructured grids with quadrilateral cells. The new scheme is implemented
within the code VULCAN/2D, which already includes radiation-hydrodynamics in
various approximations and can be used with arbitrarily moving meshes (ALE).
The MHD scheme, which consists of cell-centered magnetic field variables,
preserves the nodal finite difference representation of div(\bB) by
construction, and therefore any initially divergence-free field remains
divergence-free through the simulation. In this paper, we describe the new
scheme in detail and present comparisons of VULCAN/2D results with those of the
code ZEUS/2D for several one-dimensional and two-dimensional test problems. The
code now enables two-dimensional simulations of the collapse and explosion of
the rotating, magnetic cores of massive stars. Moreover, it can be used to
simulate the very wide variety of astrophysical problems for which multi-D
radiation-magnetohydrodynamics (RMHD) is relevant.Comment: 22 pages, including 11 figures; Accepted to the Astrophysical
Journal. Higher resolution figures available at
http://zenith.as.arizona.edu/~burrows/mhd-code
Radiative transfer modeling through terrestrial atmosphere and ocean accounting for inelastic scattering processes: Software package SCIATRAN.
SCIATRAN is a comprehensive software package which is designed to model radiative transfer processes in the terrestrial atmosphere and ocean in the spectral range from the ultraviolet to the thermal infrared (0.18–40 μm). It accounts for multiple scattering processes, polarization, thermal emission and ocean–atmosphere coupling. The main goal of this paper is to present a recently developed version of SCIATRAN which takes into account accurately inelastic radiative processes in both the atmosphere and the ocean. In the scalar version of the coupled ocean–atmosphere radiative transfer solver presented by Rozanov et al. [61] we have implemented the simulation of the rotational Raman scattering, vibrational Raman scattering, chlorophyll and colored dissolved organic matter fluorescence.
In this paper we discuss and explain the numerical methods used in SCIATRAN to solve the scalar radiative transfer equation including trans-spectral processes, and demonstrate how some selected radiative transfer problems are solved using the SCIATRAN package. In addition we present selected comparisons of SCIATRAN simulations with those published benchmark results, independent radiative transfer models, and various measurements from satellite, ground-based, and ship-borne instruments.
The extended SCIATRAN software package along with a detailed User's Guide is made available for scientists and students, who are undertaking their own research typically at universities, via the web page of the Institute of Environmental Physics (IUP), University of Bremen: http://www.iup.physik.uni-bremen.de
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