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Granada, Spain

Castro-Tirado A.J.,IAA CSIC
Acta Polytechnica

The Burst Observer and Optical Transient Exploring System (BOOTES), started in 1998 as a Spanish-Czech collaboration project, devoted to a study of optical emissions from gamma ray bursts (GRBs) that occur in the Universe. The first two BOOTES stations were located in Spain, and included medium size robotic telescopes with CCD cameras at the Cassegrain focus as well as all-sky cameras, with the two stations located 240 km apart. The first observing station (BOOTES-1) is located at ESAt (INTA-CEDEA) in Mazagón (Huelva) and the first light was obtained in July 1998. The second observing station (BOOTES-2) is located at La Mayora (CSIC) in Málaga and has been operating fully since July 2001. In 2009 BOOTES expanded abroad, with the third station (BOOTES-3) being installed in Blenheim (South Island, New Zealand) as result of a collaboration project with several institutions from the southern hemisphere. The fourth station (BOOTES-4) is on its way, to be deployed in 2011. Source

Mlynczak M.G.,NASA | Hunt L.H.,Science Systems And Applications Inc. | Mertens C.J.,NASA | Marshall B.T.,G and A Technical Software | And 7 more authors.
Journal of Geophysical Research: Atmospheres

We present a new approach to constrain and validate atomic oxygen (O) concentrations in the mesopause region (∼ 80 to ∼ 100 km). In a prior companion paper [Mlynczak et al., ], we presented O-atom concentrations in the mesopause region inferred from measurements of day ozone and night hydroxyl emission rates made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. The approach presented here uses the constraint of global, annual mean energy balance to derive atomic oxygen concentrations, consistent with rates of radiative cooling by carbon dioxide (CO2) and solar heating due to molecular oxygen (O2). The mathematical difference between these cooling and heating rates, on a global annual mean basis, effectively constrains the maximum heating rate for the sum of all other processes. The remaining terms, solar heating due to ozone plus a series of exothermic chemical reactions can be expressed as functions of O. This new approach enables a simple mathematical expression that yields the vertical profile of global annual mean "radiatively constrained" atomic oxygen in the mesopause region. The radiatively constrained atomic oxygen depends only on the CO2 cooling rates, O2 solar heating rates, and standard reaction rate coefficients and enthalpies. Radiative cooling and solar heating rates used in these analyses are derived from measurements made by the SABER instrument on the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. There is excellent agreement between the SABER radiatively constrained atomic oxygen and that derived from the SABER ozone and OH emission measurements over most of the mesopause region. Radiatively constrained atomic oxygen represents an upper limit on the global average O-atom concentration in the mesopause region. © 2013. American Geophysical Union. All Rights Reserved. Source

Sulentic J.J.,IAA CSIC | Marziani P.,National institute for astrophysics | Zamfir S.,University of Wisconsin - Stevens Point
Baltic Astronomy

We present evidence for two populations of quasars showing distinctly different broad line structure and kinematics. The first evidence for quasar dichotomy involve differences between radio-quiet and radio-loud sources. We proposed an alternate population A-B dichotomy based on optical, UV and X-ray spectroscopic properties. One of these populations (Pop. A: FWHM Hβ< 4000 kms-1) is largely radio-quiet, while Pop. B (FWHM Hβ> 4000 kms-1) includes most radio-loud sources and a significant number of spectroscopically indistinguishable (as far as the low-ionization lines are concerned) radio-quiet sources. Comparison of multiwavelength measures for population A and B sources reveals more/larger differences than are found between radioquiet and radio-loud sources leading us to conclude that the population A-B distinction is more fundamental. The major physical driver of these differences is likely the Eddington ratio where the Pop. A sources show logL/Lsda = 0.21.0, and the Pop. B sources show log L/L/Edd = 0.01-0.2 (for black hole masses logMBH ≈8.5). Source

Luque A.,IAA CSIC | Ebert U.,Centrum Wiskunde and Informatica CWI | Ebert U.,TU Eindhoven
Journal of Computational Physics

Streamer electrical discharges are often investigated with computer simulations of density models (also called reaction-drift-diffusion models). We review these models, detailing their physical foundations, their range of validity and the most relevant numerical algorithms employed in solving them. We focus particularly on schemes of adaptive refinement, used to resolve the multiple length scales in a streamer discharge without a high computational cost. We then report recent results from these models, emphasizing developments that go beyond cylindrically symmetrical streamers propagating in homogeneous media. These include interacting streamers, branching streamers and sprite streamers in inhomogeneous media. © 2011 Elsevier Inc. Source

Fryer C.L.,Los Alamos National Laboratory | Fryer C.L.,University of Arizona | Fryer C.L.,University of New Mexico | Belczynski K.,University of Warsaw | And 5 more authors.
Astrophysical Journal

The helium-merger gamma-ray burst (GRB) progenitor is produced by the rapid accretion onto a compact remnant (neutron star or black hole) when it undergoes a common envelope inspiral with its companion's helium core. This merger phase produces a very distinct environment around these outbursts and recent observations suggest that, in some cases, we are detecting the signatures of the past merger in the GRB afterglow. These observations allow us, for the first time, to study the specific features of the helium-merger progenitor. In this paper, we couple population synthesis calculations to our current understanding of GRB engines and common envelope evolution to make observational predictions for the helium-merger GRB population. Many mergers do not produce GRB outbursts and we discuss the implications of these mergers with the broader population of astrophysical transients. © 2013. The American Astronomical Society. All rights reserved. Source

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