Science and Business

There are two kinds of scientists in evolutionary studies that need a space of debate:  the specialists in evolutionary studies in business and all other evolutionary scientists in general. The themes of the discussion are the behaviour, growth, reproduction, and organizational structures of the firm

Modeling non-thermal emission from stellar bow shocks

Runaway O- and early B-type stars passing throughout the interstellar medium at supersonic velocities and characterized by strong stellar winds may produce bow shocks that can serve as particle acceleration sites. Previous theoretical models predict the production of high energy photons by non-thermal radiative processes, but their efficiency is still debated. We aim to test and explain the possibility of emission from the bow shocks formed by runaway stars traveling through the interstellar medium by using previous theoretical models. We apply our model to AE Aurigae, the first reported star with an X-ray detected bow shock, to BD+43 3654, in which the observations failed in detecting high energy emission, and to the transition phase of a supergiant star in the late stages of its life.From our analysis, we confirm that the X-ray emission from the bow shock produced by AE Aurigae can be explained by inverse Compton processes involving the infrared photons of the heated dust. We also predict low high energy flux emission from the bow shock produced by BD+43 3654, and the possibility of high energy emission from the bow shock formed by a supergiant star during the transition phase from blue to red supergiant.Bow shock formed by different type of runaway stars are revealed as a new possible source of high energy photons in our neighbourhood

X-ray flares on the UV Ceti-type star CC Eridani: a "peculiar" time-evolution of spectral parameters

Context: Weak flares are supposed to be an important heating agent of the outer layers of stellar atmospheres. However, due to instrumental limitations, only large X-ray flares have been studied in detail until now. Aims: We used an XMM-Newton observation of the very active BY-Dra type binary star CC Eri in order to investigate the properties of two flares that are weaker than those typically studied in the literature. Methods: We performed time-resolved spectroscopy of the data taken with the EPIC-PN CCD camera. A multi-temperature model was used to fit the spectra. We inferred the size of the flaring loops using the density-temperature diagram. The loop scaling laws were applied for deriving physical parameters of the flaring plasma. We also estimated the number of loops involved in the observed flares. Results: A large X-ray variability was found. Spectral analysis showed that all the regions in the light curve, including the flare segments, are well-described by a 3-T model with variable emission measures but, surprisingly, with constant temperatures (values of 3, 10 and 22 MK). The analysed flares lasted ~ 3.4 and 7.1 ks, with flux increases of factors 1.5-1.9. They occurred in arcades made of a few tens of similar coronal loops. The size of the flaring loops is much smaller than the distance between the stellar surfaces in the binary system, and even smaller than the radius of each of the stars. The obtained results are consistent with the following ideas: (i) the whole X-ray light curve of CC Eri could be the result of a superposition of multiple low-energy flares, and (ii) stellar flares can be scaled-up versions of solar flares.Comment: 14 pages, 12 figures. Accepted for publication in Astronomy & Astrophysic

El nuevo régimen de la reutilización de las aguas depuradas: en especial las novedades en el nuevo Plan Hidrológico de la demarcación del Segura

La reutilización de las aguas depuradas constituye una práctica adecuada para incrementar la disponibilidad del recurso. Sin embargo, las implicaciones sanitarias que pudiera conllevar hacen necesario la instauración de un marco jurídico que otorgue seguridad a los diferentes sectores implicados. La incorporación de las aguas regeneradas a la gestión integral del dominio público hidráulico implica, a su vez, su consideración en los nuevos planes hidrológicos recientemente aprobados. En la Demarcación Hidrográfica del Segura, donde el recurso se encuentra sometido a una intensa presión por los actuales y potenciales usuarios, la reutilización puede representar un relevante recurso adicional

La custodia del territorio como instrumento complementario para la protección de los espacios naturales

La presente nota analiza la evolución normativa de la custodia del territorio como estrategia complementaria de protección de los espacios naturales caracterizada por las notas de participación y voluntariedad y que goza de una creciente vitalidad y posibilidades de futuro. En especial, se trata de subrayar la evolución de los mecanismos de protección que, si bien descansaban en el ejercicio unilateral de potestades administrativas, de modo creciente se orientan a estrategias acordadas con los sectores interesados y afectados, como modo de conseguir mayor apoyo social y colaboración de los particulares en la consecución de los fines de interés general, en este caso, la utilización racional de los recursos naturales, la garantía del derecho a disfrutar de un medio ambiente adecuado y el más cabal cumplimiento de los deberes de protección

Deep XMM-Newton observation of the Eta Chamaleontis cluster

The members of the Eta Chamaleontis cluster are in an evolutionary stage in which disks are rapidly evolving. It also presents some peculiarities, such as the large fraction of binaries and accretion disks, probably related with the cluster formation process. Its proximity makes this stellar group an ideal target for studying the relation between X-ray emission and those stellar parameters. The main objective of this work is to determine general X-ray properties of the cluster members in terms of coronal temperature, column density, emission measure, X-ray luminosity and variability. We also aim to establish the relation between the X-ray luminosity of these stars and other stellar parameters, such as binarity and presence of accretion disks. A study of flare energies for each flare event and their relation with some stellar parameters is also performed. We used proprietary data from a deep XMM-Newton observation pointed at the core of the Eta Chamaleontis cluster. Specific software for the reduction of XMM-Newton data was used for the analysis of our observation. For the detection of sources, we used the wavelet-based code PWDetect. General coronal properties were derived from plasma model fitting. We also determined variability of the Eta Chamaleontis members in the EPIC field-of-view. A total of six flare-like events were clearly detected in five different stars. For them, we derived coronal properties during the flare events and pseudo-quiescent state separately. In our observations, stars that underwent a flare event have higher X-ray luminosities in the pseudo-quiescent state than cluster members with similar spectral type with no indications of flaring, independently whether they have an accretion disk or not. Observed flare energies are typical of both pre-main and main-sequence M stars. We detected no difference between flare energies of stars with and without an accretion disk.Comment: Accepted for publication in Astronomy and Astrophysics. 12 pages, 30 individual figure

Formation of X-ray emitting stationary shocks in magnetized protostellar jets

X-ray observations of protostellar jets show evidence of strong shocks heating the plasma up to temperatures of a few million degrees. In some cases, the shocked features appear to be stationary. They are interpreted as shock diamonds. We aim at investigating the physics that guides the formation of X-ray emitting stationary shocks in protostellar jets, the role of the magnetic field in determining the location, stability, and detectability in X-rays of these shocks, and the physical properties of the shocked plasma. We performed a set of 2.5-dimensional magnetohydrodynamic numerical simulations modelling supersonic jets ramming into a magnetized medium and explored different configurations of the magnetic field. The model takes into account the most relevant physical effects, namely thermal conduction and radiative losses. We compared the model results with observations, via the emission measure and the X-ray luminosity synthesized from the simulations. Our model explains the formation of X-ray emitting stationary shocks in a natural way. The magnetic field collimates the plasma at the base of the jet and forms there a magnetic nozzle. After an initial transient, the nozzle leads to the formation of a shock diamond at its exit which is stationary over the time covered by the simulations (~ 40 - 60 yr; comparable with time scales of the observations). The shock generates a point-like X-ray source located close to the base of the jet with luminosity comparable with that inferred from X-ray observations of protostellar jets. For the range of parameters explored, the evolution of the post-shock plasma is dominated by the radiative cooling, whereas the thermal conduction slightly affects the structure of the shock.Comment: Accepted for publication in Astronomy and Astrophysic

Recent changes in women’s Olympic shooting and effects in performance

In 2018, the Olympic shooting regulations were modified to increase the number of women’s shots from 40 to 60, equaling the number given to men. This research presented in this paper addresses two research issues: (1) has the performance of women’s shooting changed as a result of this increase in the number of shots? and (2) with the equalized number of shots in place, do women and men perform differently? This study included 292 shooters who competed in the 2016 and/or 2018 European Championships who all obtained top-50 results. Our sample included balanced quotas for sports (50% pistol and 50% rifle) and by category (50% women and 50% men). Both championships were held in the same facilities and in the same month of the season, but with the difference that in 2016, women had 40 shots and in 2018 they had 60 shots. We observed that women’s performances did not diminish for the pistol or the rifle category when their number of shots were increased. Men and women shot equally well with rifles, although the men’s performance with pistols was higher than that of women. We concluded that sports in which physical strength is a minor factor, as in the case of shooting, should revise their regulations in the interest of greater gender equality in sport