1,672 research outputs found
Fundamental parameters of massive stars in multiple systems: The cases of HD17505A and HD206267A
Many massive stars are part of binary or higher multiplicity systems. The
present work focusses on two higher multiplicity systems: HD17505A and
HD206267A. Determining the fundamental parameters of the components of the
inner binary of these systems is mandatory to quantify the impact of binary or
triple interactions on their evolution. We analysed high-resolution optical
spectra to determine new orbital solutions of the inner binary systems. After
subtracting the spectrum of the tertiary component, a spectral disentangling
code was applied to reconstruct the individual spectra of the primary and
secondary. We then analysed these spectra with the non-LTE model atmosphere
code CMFGEN to establish the stellar parameters and the CNO abundances of these
stars. The inner binaries of these systems have eccentric orbits with e ~ 0.13
despite their relatively short orbital periods of 8.6 and 3.7 days for
HD17505Aa and HD206267Aa, respectively. Slight modifications of the CNO
abundances are found in both components of each system. The components of
HD17505Aa are both well inside their Roche lobe, whilst the primary of
HD206267Aa nearly fills its Roche lobe around periastron passage. Whilst the
rotation of the primary of HD206267Aa is in pseudo-synchronization with the
orbital motion, the secondary displays a rotation rate that is higher. The CNO
abundances and properties of HD17505Aa can be explained by single star
evolutionary models accounting for the effects of rotation, suggesting that
this system has not yet experienced binary interaction. The properties of
HD206267Aa suggest that some intermittent binary interaction might have taken
place during periastron passages, but is apparently not operating anymore.Comment: Accepted for publication in A&
Memory of the Earth and Human Memory of Natural Disasters: the 1953 Earthquake in Western Aragón (Spain)
Occurred in 1953 in Used (Zaragoza province), an earthquake of magnitude 4.7 and intensity VII was the last destructive earthquake in the Aragón region, Spain. The remaining social memory of that event (a type of intangible geological heritage) and its influence on the perception of seismic hazard in the area are explored by means of interviews and a population survey. The results indicate that the memory is lively amongst the population within the epicentral area, both in the generation that experienced it and, to a lesser extent, in the following generations. However, this does not translate into a significant perception of seismic hazard, the latter being more influenced by cultural factors: in the epicentral area it is greater amongst people who did not live through the earthquake, but who have heard familiar stories or have had external information highlighteing its importance. The study of social perception is part of a citizen science project, in which the social memory enters into dialogue with the Memory of the Earth, i.e. the record left by that and other previous earthquakes in geology and landscape. The research on the effects of the shake on people, buildings, and environment has benefited from numerous testimonies from the elderly. Reciprocally, such knowledge is scientifically processed and returned to the citizens in the form of scientific outreach products (book, documentary film, talks), with the aim of promoting scientific culture about natural disasters
El comercio de las «cosas intelectuales»: aproximación al concepto de productos informativo-documentales.
Sin resume
The spectroscopic Hertzsprung-Russell diagram of Galactic massive stars
The distribution of stars in the Hertzsprung-Russell diagram narrates their
evolutionary history and directly assesses their properties. Placing stars in
this diagram however requires the knowledge of their distances and interstellar
extinctions, which are often poorly known for Galactic stars. The spectroscopic
Hertzsprung-Russell diagram (sHRD) tells similar evolutionary tales, but is
independent of distance and extinction measurements. Based on spectroscopically
derived effective temperatures and gravities of almost 600 stars, we derive for
the first time the observational distribution of Galactic massive stars in the
sHRD. While biases and statistical limitations in the data prevent detailed
quantitative conclusions at this time, we see several clear qualitative trends.
By comparing the observational sHRD with different state-of-the-art stellar
evolutionary predictions, we conclude that convective core overshooting may be
mass-dependent and, at high mass (), stronger than previously
thought. Furthermore, we find evidence for an empirical upper limit in the sHRD
for stars with between 10000 and 32000 K and, a strikingly large
number of objects below this line. This over-density may be due to inflation
expanding envelopes in massive main-sequence stars near the Eddington limit.Comment: 5 pages, 2 figures, 1 table; accepted for publication in A&A Letter
B-type supergiants in the SMC: Rotational velocities and implications for evolutionary models
High-resolution spectra for 24 SMC and Galactic B-type supergiants have been
analysed to estimate the contributions of both macroturbulence and rotation to
the broadening of their metal lines. Two different methodologies are
considered, viz. goodness-of-fit comparisons between observed and theoretical
line profiles and identifying zeros in the Fourier transforms of the observed
profiles. The advantages and limitations of the two methods are briefly
discussed with the latter techniques being adopted for estimated projected
rotational velocities (\vsini) but the former being used to estimate
macroturbulent velocities. Only one SMC supergiant, SK 191, shows a significant
degree of rotational broadening (\vsini 90 \kms). For the remaining
targets, the distribution of projected rotational velocities are similar in
both our Galactic and SMC samples with larger values being found at earlier
spectral types. There is marginal evidence for the projected rotational
velocities in the SMC being higher than those in the Galactic targets but any
differences are only of the order of 5-10 \kms, whilst evolutionary models
predict differences in this effective temperature range of typically 20 to 70
\kms. The combined sample is consistent with a linear variation of projected
rotational velocity with effective temperature, which would imply rotational
velocities for supergiants of 70 \kms at an effective temperature of 28 000 K
(approximately B0 spectral type) decreasing to 32 \kms at 12 000 K (B8 spectral
type). For all targets, the macroturbulent broadening would appear to be
consistent with a Gaussian distribution (although other distributions cannot be
discounted) with an half-width varying from approximately 20 \kms
at B8 to 60 \kms at B0 spectral types.Comment: 4 figures, 8 pages, submitted to Astronomy and Astrophysic
Resultados de la inspección veterinaria ante y post-mortem en un matadero de bovino, ovino y caprino
Se presentan los resultados de la inspección veterinaria de bovinos, ovinos y caprinos en un matadero de servicios de La Selva (Gerona). Además se hace una reflexión sobre la metodología empleada en la recogida de datos, y la necesidad de valorarlo de forma homogénea, de modo que tenga validez para el control sanitario de las explotaciones ganaderas y para la protección de la Salud Públic
Segmentation and increasing activity in the Neogene-Quaternary Teruel Basin rift (Spain) revealed by morphotectonic approach
The NNW-SSE trending Teruel Basin rift is the largest Late Miocene-Quaternary extensional intracontinental structure located within the central-eastern Iberian Chain (Spain). The structural and morphotectonic study carried out in the central-northern part of this half graben basin (north of Teruel city) has allowed us to analyse rift segmentation, deformation partitioning and rift evolution. Results are based on vertical displacement calculations (fault throw and bending) of the main border and intrabasin fault zones. We use two geomorfological-stratigraphical markers, the Intramiocene Erosion Surface (IES; 11.2 Ma) and the Fundamental Erosion Surface (FES; 3.5 Ma). While the first marker reveals rift initiation under an E-W extension, the late marker records vertical displacements associated to a second, Late Pliocene–Quaternary rifting stage characterized by a nearly multidirectional extension regime with prevailing ENE-WSW trending ó3. Despite the along-axis rift segmentation into three structural domains (northern, central and southern) and the distribution of deformation among border and intrabasin faults in the central and southern domains, a consistent average slip rate (post-IES) of 0.09 mm/a has been calculated on distinct transects across the basin, suggesting a homogeneous crustal-scale extension process in the region. The results also reveal that slip rates during the Late Pliocene-Quaternary (0.12–0.16 mm/a) are higher than the Late Miocene-Early Pliocene (0.05–0.07 mm/a). Slip rate increase is caused by (i) a westward propagation of deformation from the Valencia Through, and (ii) a change in the regional stress field, both enhanced by crustal doming affecting central-eastern Iberia, as well as progressive fault linkage. Throw vs. distance graphs suggest that the main faults are in a transient stage towards coalescence, less advanced within the southern domain. Regional Late Pliocene-Quaternary uplift, concomitant with increasing slip rates in the Teruel Basin rift, has caused the basin to rise, so that synrift sedimentation only took place in rapidly subsiding residual basins until the region became exorheic and the basin was incised by the present-day fluvial network
Los valles tectónicos recientes de Rubielos de la Cerida (Teruel)
[Resumen] La actividad tectónica cuaternaria y reciente ha dado lugar en este área a un conjunto de depresiones alargadas de orientación submeridiana, enmarcadas por fallas, que constituyen valles tectónicos[Abstract] Quaternary and recent tectonic activity led to a series of elongated depressions in the studied area of roughly N-S orientation, framed by faults, and developping as tectonic valleys
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