Chemical abundances of late-type pre-main sequence stars in the σ\sigma-Orionis cluster

The young $\sigma$-Orionis cluster is an important location for understanding the formation and evolution of stars, brown dwarfs, and planetary-mass objects. Its metallicity, although being a fundamental parameter, has not been well determined yet. We present the first determination of the metallicity of nine young late-type stars in $\sigma$-Orionis. Using the optical and near-infrared broadband photometry available in the literature we derive the effective temperatures for these nine cluster stars, which lie in the interval 4300--6500 K (1--3 \Msuno). These parameters are employed to compute a grid of synthetic spectra based on the code MOOG and Kurucz model atmospheres. We employ a $\chi^2$-minimization procedure to derive the stellar surface gravity and atmospheric abundances of Al, Ca, Si, Fe, Ni and Li, using multi-object optical spectroscopy taken with WYFFOS+AF2 at at the William Herschel Telescope ($\lambda/\delta\lambda\sim7500$). The average metallicity of the $\sigma$-Orionis cluster is [Fe/H] $= -0.02\pm0.09\pm0.13$ (random and systematic errors). The abundances of the other elements, except lithium, seem to be consistent with solar values. Lithium abundances are in agreement with the "cosmic" $^7$Li abundance, except for two stars which show a $\log \epsilon(\mathrm{Li})$ in the range 3.6--3.7 (although almost consistent within the error bars). There are also other two stars with $\log \epsilon(\mathrm{Li})\sim 2.75$. We derived an average radial velocity of the $\sigma$-Orionis cluster of $28\pm4$km/s. The $\sigma$-Orionis metallicity is roughly solar.Comment: Accepted for publication in Astronomy and Astrophysic

A new L-dwarf member of the moderately metal-poor triple system HD 221356

We report on the discovery of a fourth component in the HD 221356 star system, previously known to be formed by an F8V, slightly metal-poor primary ([Fe/H]=-0.26), and a distant M8V+L3V pair. In our ongoing common proper motion search based on VISTA Hemisphere Survey (VHS) and 2MASS catalogues, we have detected a faint (J=13.76+/-0.04 mag) co-moving companion of the F8 star located at angular separation of 12.13+/-0.18 arcsec (position angle of 221.8+/-1.7), corresponding to a projected distance of ~312 AU at 26 pc. Near-infrared spectroscopy of the new companion, covering the 1.5-2.4 micron wavelength range with a resolving power of R~600, indicates an L1+/-1 spectral type. Using evolutionary models the mass of the new companion is estimated at ~0.08 solar masses, which places the object close to the stellar-substellar borderline. This multiple system provides an interesting example of objects with masses slightly above and below the hydrogen burning mass limit. The low mass companions of HD 221356 have slightly bluer colours than field dwarfs with similar spectral type, which is likely a consequence of the sub-solar metallicity of the system.Comment: 7 pages, 4 figures, accepted for publication in MNRA

Спостереження як метод державного фінансового контролю за сплатою податків суб'єктами малого підприємництва

У статті проаналізовано особливості державного контролю за діяльністю суб’єктів малого підприємництва. Наведено авторське визначення методу спостереження в державному фінансовому контролі за сплатою податків та обґрунтовано доцільність його застосування в перспективі. (The features of state control over the activities of small businesses are analyzed. The author’s definition of the method of monitoring in the state financial control over tax payments is given, and the expedience for its use in the prospects is grounded.

A census of very-low-mass stars and brown dwarfs in the sigma Orionis cluster

(ABRIDGED) We have analysed the near-infrared photometric data from the Fourth Data Release (DR4) of the UKIRT Infrared Deep Sky Suvey (UKIDSS) Galactic Clusters Survey (GCS) to derive the cluster luminosity and mass functions, evaluate the extent of the cluster, and study the distribution and variability of low-mass stars and brown dwarfs down to the deuterium-burning limit. We have recovered most of the previously published members and found a total of 287 candidate members within the central 30 arcmin in the 0.5-0.009 Msun mass range, including new objects not previously reported in the literature. This new catalogue represents a homogeneous dataset of brown dwarf member candidates over the central 30 arcmin of the cluster. The expected photometric contamination by field objects with similar magnitudes and colours to sigma Orionis members is ~15%. We present evidence of variability at the 99.5% confidence level over ~yearly timescales in 10 member candidates that exhibit signs of youth and the presence of disks. The level of variability is low (<0.3 mag) and does not impact the derivation of the cluster luminosity and mass functions. Furthermore, we find a possible dearth of brown dwarfs within the central five arcmin of the cluster, which is not caused by a lower level of photometric sensitivity around the massive, O-type multiple star sigma Ori in the GCS survey. Using state-of-the-art theoretical models, we derived the luminosity and mass functions within the central 30 arcmin from the cluster centre, with completeness down to J = 19 mag, corresponding to masses ranging from 0.5 Msun down to the deuterium-burning mass boundary (~0.013 Msun). The mass function of sigma Orionis in this mass interval shows a power law index alpha = 0.5+/-0.2.Comment: 16 pages, 10 figures, 4 Tables, and appendix containing 6 tables including tables in electronic format only. Revised version corrected for english. Table 4 has been updated and correcte

The CARMENES search for exoplanets around M dwarfs. A sub-Neptunian mass planet in the habitable zone of HN Lib

We report the discovery of HN Lib b, a sub-Neptunian mass planet orbiting the nearby ($d \approx$ = 6.25 pc) M4.0 V star HN Lib detected by our CARMENES radial-velocity (RV) survey. We determined a planetary minimum mass of $M_\text{b}\sin i =$ 5.46 $\pm$ 0.75 $\text{M}_\oplus$ and an orbital period of $P_\text{b} =$ 36.116 $\pm$ 0.029 d, using $\sim$5 yr of CARMENES data, as well as archival RVs from HARPS and HIRES spanning more than 13 years. The flux received by the planet equals half the instellation on Earth, which places it in the middle of the conservative habitable zone (HZ) of its host star. The RV data show evidence for another planet candidate with $M_\text{[c]}\sin i =$ 9.7 $\pm$ 1.9 $\text{M}_\oplus$ and $P_\text{[c]} =$ 113.46 $\pm$ 0.20 d. The long-term stability of the signal and the fact that the best model for our data is a two-planet model with an independent activity component stand as strong arguments for establishing a planetary origin. However, we cannot rule out stellar activity due to its proximity to the rotation period of HN Lib, which we measured using CARMENES activity indicators and photometric data from a ground-based multi-site campaign as well as archival data. The discovery adds HN Lib b to the shortlist of super-Earth planets in the habitable zone of M dwarfs, but HN Lib [c] probably cannot be inhabited because, if confirmed, it would most likely be an icy giant

Perspectiva de futuro, patrones de aprendizaje y rendimiento académico en estudiantes universitarios mexicanos

The purpose of this study was to analyze the relationship between future perspective, the adoption of different learning patterns, and academic performance of university students. Participants were 175 students, average age 20, who responded to the Time Perspective Inventory (ZTPI) and the Inventory of Learning Styles (ILS). Results show that learning patterns play a mediating role between future perspectives and academic performance. We suggest the promotion of more equitable teaching contexts that affect the adoption of learning patterns aimed at understanding of meanings.Este estudio tuvo como propósito analizar la relación entre la perspectiva de futuro, la dominancia de distintos patrones de aprendizaje y el rendimiento académico en estudiantes universitarios. Participaron 175 estudiantes, con edad media de 20 años, que respondieron al Inventario de Perspectiva Temporal (ZTPI) y al Inventario de Estilos de Aprendizaje (ILS). Los resultados muestran que existe un papel mediador de los patrones de aprendizaje entre la perspectiva de futuro y el rendimiento académico. Se sugiere generar contextos de enseñanza que incidan en la adopción del patrón de aprendizaje dirigido a la comprensión de significados

The CARMENES search for exoplanets around M dwarfs -- A deep learning approach to determine fundamental parameters of target stars

Existing and upcoming instrumentation is collecting large amounts of astrophysical data, which require efficient and fast analysis techniques. We present a deep neural network architecture to analyze high-resolution stellar spectra and predict stellar parameters such as effective temperature, surface gravity, metallicity, and rotational velocity. With this study, we firstly demonstrate the capability of deep neural networks to precisely recover stellar parameters from a synthetic training set. Secondly, we analyze the application of this method to observed spectra and the impact of the synthetic gap (i.e., the difference between observed and synthetic spectra) on the estimation of stellar parameters, their errors, and their precision. Our convolutional network is trained on synthetic PHOENIX-ACES spectra in different optical and near-infrared wavelength regions. For each of the four stellar parameters, $T_{\rm eff}$, $\log{g}$, [M/H], and $v \sin{i}$, we constructed a neural network model to estimate each parameter independently. We then applied this method to 50 M dwarfs with high-resolution spectra taken with CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs), which operates in the visible (520-960 nm) and near-infrared wavelength range (960-1710 nm) simultaneously. Our results are compared with literature values for these stars. They show mostly good agreement within the errors, but also exhibit large deviations in some cases, especially for [M/H], pointing out the importance of a better understanding of the synthetic gap

Application of multi-sensor advanced DInSAR analysis to severe land subsidence recognition: Alto Guadalentín Basin (Spain)

Multi-sensor advanced DInSAR analyses have been performed and compared with two GPS station measurements, in order to evaluate the land subsidence evolution in a 20-year period, in the Alto Guadalentín Basin where the highest rate of man-induced subsidence (> 10 cm yr&minus;1) of Europe had been detected. The control mechanisms have been examined comparing the advanced DInSAR data with conditioning and triggering factors (i.e. isobaths of Plio-Quaternary deposits, soft soil thickness and piezometric level)

A new teaching strategy to teach microbiology through its history

Ante el nuevo reto de la implantación del Espacio Europeo de Educación Superior los métodos de estudio deben adaptarse y servirse de herramientas innovadoras. Una buena estrategia para comprender una ciencia, su metodología y objetivos, es conocer su historia. Esta estrategia se hace especialmente útil en el caso de la Microbiología por ser una disciplina joven, que se ha cimentado precisamente en la metodología que sus creadores han ido elaborando. El objetivo de este trabajo ha sido crear una herramienta de utilidad en el aprendizaje de la Microbiología. Para ello hemos tomado como punto de apoyo su historia, es decir, explicar la Microbiología mediante la descripción de los descubrimientos y hechos que contribuyeron al desarrollo de esta ciencia. Para ello se ha creado una página web con dos aplicaciones independientes que operan sobre una base de datos común. 1. La primera de carácter público para los alumnos aunque con posibilidad de acceso restringido; se pueden consultar los contenidos sin posibilidad de alterarlos. 2. La otra aplicación es privada, los profesores pueden administrar los contenidos, y hacer uso de diferentes herramientas que facilitan la gestión de los mismos.In the light of the challenge presented by the European Higher Education Area, study strategies will have to adapt themselves and take advantage of innovative tools provided by modern information technology. One good way of understanding a science, its methodology and objectives is by taking an interest in its history. This approach is especially useful with regard to Microbiology, which is a fairly young discipline founded upon and made cohesive by the methods devised and constantly elaborated on by its designers. The aim of this work has been to offer guidance towards learning Microbiology. To this end we have chosen as our starting point, and indeed one of the keystones of our approach, the history of the subject itself; that is to say, an explanation of Microbiology via a description of the discoveries and milestones that have contributed to the development of this science. Thus we have set up a web page with two separate applications operating on one common database. 1. The first is openly available to the students, although allowing the possibility of restricted access. Its contents may be consulted but not altered. 2. The second is accessible only by lecturers, who may administer its contents and resort to different tools to facilitate the management of the information available on the site

Candidate free-floating super-Jupiters in the young sigma Orionis open cluster

Free-floating substellar candidates with estimated theoretical masses of as low as ~5 Jupiter masses have been found in the ~3 Myr old sigma Orionis open cluster. As the overlap with the planetary mass domain increases, the question of how these objects form becomes important. The determination of their number density and whether a mass cut-off limit exists is crucial to understanding their formation. We propose to search for objects of yet lower masses in the cluster and determine the shape of the mass function at low mass. Using new- and (re-analysed) published IZJHKs[3.6]-[8.0]-band data of an area of 840 arcmin2, we performed a search for LT-type cluster member candidates in the magnitude range J=19.5-21.5 mag, based on their expected magnitudes and colours. Besides recovering the T type object S Ori 70 and two other known objects, we find three new cluster member candidates, S Ori 72-74, with J=21 mag and within 12 arcmin of the cluster centre. They have theoretical masses of 4 (-2,+3) M_Jup and are among the least massive free-floating objects detected by direct imaging outside the Solar System. The photometry in archival Spitzer [3.6]-[5.8]-band images infers that S Ori 72 is an L/T transition candidate and S Ori 73 a T-type candidate, following the expected cluster sequence in the mid-infrared. Finally, the L-type candidate S Ori 74 with lower quality photometry is located at 11.8 arcsec (~4250 AU) of a stellar member of sigma Orionis and could be a companion. After contaminant correction in the area complete to J=21.1 mag, we estimate that there remain between zero and two cluster members in the mass interval 6-4 M_Jup. Our result suggests a possible turnover in the substellar mass spectrum below ~6 Jupiter masses, which could be investigated further by wider and deeper photometric surveys.Comment: 15 pages, 13 figures, 5 tables, and appendix containing 5 figures; accepted for publication in AA; v2: 2 minor corrections, in abstract and sect. 2.