Ciencia y Teología en el Renacimiento paleólogo entre Oriente y Occidente: el caso de Isaac Argiro

Isaac Argiro (1310-1375 ca.) siguió la estela de su maestro, Nicéforo Gregorás, tanto en el cultivo de la ciencia profana como en la oposición a la teología de Gregorio Palamás, que Argiro combatió incluso en la persona del emperador Juan VI Cantacuceno. Además de esas inclinaciones espirituales, Isaac Argiro se interesó también por la astrología, como prueba el hecho de que copiara íntegro el Laurent. Plut. 28, 13, que fue el modelo de los manuscritos que se produjeron en el círculo de Juan Abramio, el astrólogo de Andrónico IV (Laurent. Plut. 28, 16, Marc. Gr. 324, Laurent. Plut. 28, 14 y Taurin. C. VII. 10). Esta comunicación trata de estudiar la vinculación entre el interés de Argiro por la astronomía y la astrología de la Grecia Antigua y sus posiciones filosóficas y teológicas, tal como fueron expresadas en sus opúsculos antipalamitas, así como su acercamiento a los círculos intelectuales bizantinos más proclives a un entendimiento con el Papado con vistas a la unión de las Iglesias de Roma y Constantinopla.

Southern Hemisphere Summer Mesopause Responses to El Niño-Southern Oscillation

In the Southern Hemisphere (SH) polar region, satellite observations reveal a significant upper-mesosphere cooling and a lower-thermosphere warming during warm ENSO events in December. An opposite pattern is observed in the tropical mesopause region. The observed upper-mesosphere cooling agrees with a climate model simulation. Analysis of the simulation suggests that enhanced planetary wave (PW) dissipation in the Northern Hemisphere (NH) high-latitude stratosphere during El Nino strengthens the Brewer-Dobson circulation and cools the equatorial stratosphere. This increases the magnitude of the SH stratosphere meridional temperature gradient and thus causes the anomalous stratospheric easterly zonal wind and early breakdown of the SH stratospheric polar vortex. The resulting perturbation to gravity wave (GW) filtering causes anomalous SH mesospheric eastward GW forcing and polar upwelling and cooling. In addition, constructive inference of ENSO and quasi-biennial oscillation (QBO) could lead to stronger stratospheric easterly zonal wind anomalies at the SH high latitudes in November and December and early breakdown of the SH stratospheric polar vortex during warm ENSO events in the easterly QBO phase (defined by the equatorial zonal wind at similar to 25 hPa). This would in turn cause much more SH mesospheric eastward GW forcing and much colder polar temperatures, and hence it would induce an early onset time of SH summer polar mesospheric clouds (PMCs). The opposite mechanism occurs during cold ENSO events in the westerly QBO phase. This implies that ENSO together with QBO could significantly modulate the breakdown time of SH stratospheric polar vortex and the onset time of SH PMC.

Ondas Gravitacionales: el amanecer de una nueva era

Después de una larga espera de decenas de años estamos de enhorabuena: el 14 de Septiembre de 2015 una colaboración científica internacional (LIGO/VIRGO) logró detectar, en sus interferómetros más avanzados en funcionamiento, lo que llevábamos esperando con tanta ansia: una onda gravitatoria. La primera de la historia. Poco después, el 26 de Diciembre, se detectó la segunda. El logro científico-técnico es imponente: medir una variación de longitud equivalente a la del tamaño del radio atómico en la distancia entre la Tierra y el Sol. ¿Se puede medir eso?. ¡Se ha hecho!. Simultáneamente, hemos podido observar, por partida doble y directamente, un sistema binario de agujeros negros. ¡Sensacional!. Lo mejor, con seguridad, está por llegar. Estos hechos excepcionales e históricos demuestran que la humanidad se ha dotado de un nuevo "sentido" para observar el Universo, una nueva ventana por la que escudriñar lo que hay ahí fuera. Hasta ahora éramos insensibles a la radiación gravitatoria, a partir de ahora ya podemos "gravi-sentir" el Universo. La nueva era de la "Astronomía por gravedad” ha empezado. En esta conferencia se explicará, de forma amena y asequible, qué es una onda gravitatoria, cómo y con qué aparatos se mide, la información que porta, sus diferencias con otras ondas cotidianas. Veremos así que todo lo que a partir de ahora se descubrirá superará todas nuestras expectativas, cambiará nuestra cosmovisión radicalmente, nos aportará sorpresas impensables. Los cielos están henchidos de "luceros gravitatorios", ignotos hasta ahora, inenarrables. Podremos conocerlos y estudiarlos. Aprender acerca de, y comprender, el firmamento. Todo lo que existe, sea visible o invisible, gravita. Podremos por ello observar, e indagar, todo el Universo, sus más recónditos rincones y hasta su origen. Explicaremos, en definitiva, por qué nos encontramos en los albores de una nueva etapa para la humanidad, un momento único y apasionante. ¡No se lo pierdan!

Athanasii Kircheri Fuldensis Buchonii... Ars magna lucis et umbrae, in decem libros digesta. Quibus admirandae lucis et umbrae in mundo, atque adeò vniuersa natura, vires effectusq. vti noua, uti varia nouorum reconditiorumq. speciminum exhibitione, ad varios mortalium vsus, panduntur...

En port. grab. xil. de sol con lema: "Sicuti tenebrae eius ita & lumen eius. Psal. 138"

The multiphase starburst-driven galactic wind in NGC 5394

We present a detailed study of the neutral and ionized gas phases in the galactic wind for the nearby starburst galaxy NGC 5394 based on new integral field spectroscopy obtained with the INTEGRAL fibre system at the William Herschel Telescope. The neutral gas phase in the wind is detected via the interstellar Na I D doublet absorption. After a careful removal of the stellar contribution to these lines, a significant amount of neutral gas (∼10^7 M_⊙) is detected in a central region of ∼1.75 kpc size. This neutral gas is blueshifted by ∼165 km s^−1 with respect to the underlying galaxy. The mass outflow of neutral gas is comparable to the star formation rate of the host galaxy. Simultaneously, several emission lines (Hα, [N II], [S II]) are also analysed looking for the ionized warm phase counterpart of the wind. A careful kinematic decomposition of the line profiles reveals the presence of a secondary, broader, kinematic component. This component is found roughly in the same region where the Na I D absorption is detected. It presents higher [N II]/Hα and [S II]/Hα line ratios than the narrow component at the same locations, indicative of contamination by shock ionization. This secondary component also presents blueshifted velocities, although smaller than those measured for the neutral gas, averaging to ∼−30 km s^−1. The mass and mass outflow rate of the wind is dominated by the neutral gas, of which a small fraction might be able to escape the gravitational potential of the host galaxy. The observations in this system can be readily understood within a bipolar gas flow scenario.

Documentary sources to investigate multidecadal variability of droughts

Droughts are probably the natural hazard with the highest socioeconomic impact. Simultaneously, they are a very complex phenomenon; they are triggered by a diversity of physical factors and occur at a variety of time scales. Consequently, the instrumental record currently available is too short and the characterization of its multidecadal variability requires the use of natural proxies (tree rings, sedimentary records) or documentary sources. In this paper we analyse three documentary sources with potential to analyse the long-term variability of droughts: chapter acts, logbooks and chronicles. The chapter acts recorded discussions and decisions made during the assemblies of the local authorities and provide continuous and direct evidence on drought impacts. They are especially useful to study droughts between the 15th and the 19th centuries in Europe and the 17th to 18th in the former colonies. Logbooks recorded the meteorological conditions and the incidents occurred during navigation. They provide indirect information through the circulation indices that can be very helpful to understand the mechanisms and teleconnections associated to droughts. Finally, the chronicles are historiographical documents describing political and social events. They are secondary sources and the references to climatic events are discontinuous, thus their analysis must be extremely careful, but they are especially useful to study specific drought events especially prior to 15th century when no other sources are available.

The Califa and Hipass circular velocity function for all morphological galaxy types

The velocity function (VF) is a fundamental observable statistic of the galaxy population that is similar to the luminosity function in importance, but much more difficult to measure. In this work we present the first directly measured circular VF that is representative between 60 < v_circ < 320 km s^-1 for galaxies of all morphological types at a given rotation velocity. For the low-mass galaxy population (60 < v_circ < 170 km s^-1), we use the HI Parkes All Sky Survey VF. For the massive galaxy population (170 < v_circ < 320 km s^-1), we use stellar circular velocities from the Calar Alto Legacy Integral Field Area Survey (CALIFA). In earlier work we obtained the measurements of circular velocity at the 80% light radius for 226 galaxies and demonstrated that the CALIFA sample can produce volume-corrected galaxy distribution functions. The CALIFA VF includes homogeneous velocity measurements of both late and early-type rotation-supported galaxies and has the crucial advantage of not missing gas-poor massive ellipticals that HI surveys are blind to. We show that both VFs can be combined in a seamless manner, as their ranges of validity overlap. The resulting observed VF is compared to VFs derived from cosmological simulations of the z = 0 galaxy population. We find that dark-matter-only simulations show a strong mismatch with the observed VF. Hydrodynamic simulations fare better, but still do not fully reproduce observations.

Sub-kiloparsec alma imaging of compact star-forming galaxies at z ~ 2.5: revealing the formation of dense galactic cores in the progenitors of compact quiescent galaxies

We present spatially resolved Atacama Large Millimeter/submillimeter Array (ALMA) 870 μm dust continuum maps of six massive, compact, dusty star-forming galaxies at z ~ 2.5. These galaxies are selected for their small rest-frame optical sizes (r_e,F160W ~ 1.6 kpc) and high stellar mass densities that suggest that they are direct progenitors of compact quiescent galaxies at z ~ 2. The deep observations yield high far-infrared (FIR) luminosities of L_IR = 10^12.3-12.8 L_⨀ and star formation rates (SFRs) of SFR = 200–700 M_⊙ yr^−1, consistent with those of typical star-forming "main sequence" galaxies. The high spatial resolution (FWHM ~ 0 12–0 18) ALMA and Hubble Space Telescope photometry are combined to construct deconvolved, mean radial profiles of their stellar mass and (UV+IR) SFR. We find that the dusty, nuclear IR–SFR overwhelmingly dominates the bolometric SFR up to r ~ 5 kpc, by a factor of over 100× from the unobscured UV–SFR. Furthermore, the effective radius of the mean SFR profile (r_e,SFR ~ 1 kpc) is ~30% smaller than that of the stellar mass profile. The implied structural evolution, if such nuclear starburst last for the estimated gas depletion time of Δt = ±100 Myr, is a 4×increase of the stellar mass density within the central 1 kpc and a 1.6× decrease of the half-mass–radius. This structural evolution fully supports dissipation-driven, formation scenarios in which strong nuclear starbursts transform larger, star-forming progenitors into compact quiescent galaxies.

Breaking the curve with candels: a Bayesian approach to reveal the non-universality of the dust-attenuation law at high redshift

Dust attenuation affects nearly all observational aspects of galaxy evolution, yet very little is known about the form of the dust-attenuation law in the distant universe. Here, we model the spectral energy distributions of galaxies at z ~ 1.5–3 from CANDELS with rest-frame UV to near-IR imaging under different assumptions about the dust law, and compare the amount of inferred attenuated light with the observed infrared (IR) luminosities. Some individual galaxies show strong Bayesian evidence in preference of one dust law over another, and this preference agrees with their observed location on the plane of infrared excess (IRX, L_TIR/L_UV) and UV slope (β). We generalize the shape of the dust law with an empirical model, A_ λ,σ =E(B-V)k_ λ (λ / λ v)^ σ where k_λ is the dust law of Calzetti et al., and show that there exists a correlation between the color excess E(B-V) and tilt δ with δ =(0.62±0.05)log(E(B-V))+(0.26±0.02). Galaxies with high color excess have a shallower, starburst-like law, and those with low color excess have a steeper, SMC-like law. Surprisingly, the galaxies in our sample show no correlation between the shape of the dust law and stellar mass, star formation rate, or β. The change in the dust law with color excess is consistent with a model where attenuation is caused by scattering, a mixed star–dust geometry, and/or trends with stellar population age, metallicity, and dust grain size. This rest-frame UV-to-near-IR method shows potential to constrain the dust law at even higher redshifts (z>3).

Reconstructing the last interglacial at Summit, Greenland: Insights from GISP2

The Eemian (last interglacial, 130-115 ka) was likely the warmest of all interglacials of the last 800 ka, with summer Arctic temperatures 3-5 degrees C above present. Here, we present improved Eemian climate records from central Greenland, reconstructed from the base of the Greenland Ice Sheet Project 2 (GISP2) ice core. Our record comes from clean, stratigraphically disturbed, and isotopically warm ice from 2,750 to 3,040 m depth. The age of this ice is constrained by measuring CH_4 and delta O^18 of O_2, and comparing with the historical record of these properties from the North Greenland Ice Core Project (NGRIP) and North Greenland Eemian Ice Drilling (NEEM) ice cores. The d^18 O_ice, d^15N of N_2, and total air content for samples dating discontinuously from 128 to 115 ka indicate a warming of similar to 6 degrees C between 127-121 ka, and a similar elevation history between GISP2 and NEEM. The reconstructed climate and elevation histories are compared with an ensemble of coupled climate-ice-sheet model simulations of the Greenland ice sheet. Those most consistent with the reconstructed temperatures indicate that the Greenland ice sheet contributed 5.1 m (4.1-6.2 m, 95% credible interval) to global eustatic sea level toward the end of the Eemian. Greenland likely did not contribute to anomalously high sea levels at ~127 ka, or to a rapid jump in sea level at ~120 ka. However, several unexplained discrepancies remain between the inferred and simulated histories of temperature and accumulation rate at GISP2 and NEEM, as well as between the climatic reconstructions themselves.

Mass assembly and morphological transformations since z ∼ 3 from CANDELS

We quantify the evolution of the stellar mass functions (SMFs) of star-forming and quiescent galaxies as a function of morphology from z ∼ 3 to the present. Our sample consists of ∼50 000 galaxies in the CANDELS fields (∼880 arcmin^2), which we divide into four main morphological types, i.e. pure bulge-dominated systems, pure spiral disc-dominated, intermediate two-component bulge+disc systems and irregular disturbed galaxies. At z ∼ 2, 80 per cent of the stellar mass density of star-forming galaxies is in irregular systems. However, by z ∼ 0.5, irregular objects only dominate at stellar masses below 10^9 M_⊙. A majority of the star-forming irregulars present at z ∼ 2 undergo a gradual transformation from disturbed to normal spiral disc morphologies by z ∼ 1 without significant interruption to their star formation. Rejuvenation after a quenching event does not seem to be common except perhaps for the most massive objects, because the fraction of bulge-dominated star-forming galaxies with M^*/M_⊙ > 10^10.7 reaches 40 per cent at z < 1. Quenching implies the presence of a bulge: the abundance of massive red discs is negligible at all redshifts over 2 dex in stellar mass. However, the dominant quenching mechanism evolves. At z > 2, the SMF of quiescent galaxies above M^* is dominated by compact spheroids. Quenching at this early epoch destroys the disc and produces a compact remnant unless the star-forming progenitors at even higher redshifts are significantly more dense. At 1 < z < 2, the majority of newly quenched galaxies are discs with a significant central bulge. This suggests that mass quenching at this epoch starts from the inner parts and preserves the disc. At z < 1, the high-mass end of the passive SMF is globally in place and the evolution mostly happens at stellar masses below 10^10 M_⊙. These low-mass galaxies are compact, bulge-dominated systems, which were environmentally quenched: destruction of the disc through ram-pressure stripping is the likely process.

Space density distribution of galaxies in the absolute magnitude - rotation velocity plane: a volume-complete Tully-Fisher relation from CALIFA stellar kinematics

We measured the distribution in absolute magnitude - circular velocity space for a well-defined sample of 199 rotating galaxies of the Calar Alto Legacy Integral Field Area Survey (CALIFA) using their stellar kinematics. Our aim in this analysis is to avoid subjective selection criteria and to take volume and large-scale structure factors into account. Using stellar velocity fields instead of gas emission line kinematics allows including rapidly rotating early-type galaxies. Our initial sample contains 277 galaxies with available stellar velocity fields and growth curve r-band photometry. After rejecting 51 velocity fields that could not be modelled because of the low number of bins, foreground contamination, or significant interaction, we performed Markov chain Monte Carlo modelling of the velocity fields, from which we obtained the rotation curve and kinematic parameters and their realistic uncertainties. We performed an extinction correction and calculated the circular velocity v_circ accounting for the pressure support of a given galaxy. The resulting galaxy distribution on the M-r - v(circ) plane was then modelled as a mixture of two distinct populations, allowing robust and reproducible rejection of outliers, a significant fraction of which are slow rotators. The selection effects are understood well enough that we were able to correct for the incompleteness of the sample. The 199 galaxies were weighted by volume and large-scale structure factors, which enabled us to fit a volume-corrected Tully-Fisher relation (TFR). More importantly, we also provide the volume-corrected distribution of galaxies in the M_r - v_circ plane, which can be compared with cosmological simulations. The joint distribution of the luminosity and circular velocity space densities, representative over the range of -20 > M_r > -22 mag, can place more stringent constraints on the galaxy formation and evolution scenarios than linear TFR fit parameters or the luminosity function alone.

Incidence of debris discs around FGK stars in the solar neighbourhood

Context. Debris discs are a consequence of the planet formation process and constitute the fingerprints of planetesimal systems. Their counterparts in the solar system are the asteroid and Edgeworth-Kuiper belts. Aims. The aim of this paper is to provide robust numbers for the incidence of debris discs around FGK stars in the solar neighbourhood. Methods. The full sample of 177 FGK stars with d ≤ 20 pc proposed for the DUst around NEarby Stars (DUNES) survey is presented. Herschel/PACS observations at 100 and 160 μm were obtained, and were complemented in some cases with data at 70 μm and at 250, 350, and 500 μm SPIRE photometry. The 123 objects observed by the DUNES collaboration were presented in a previous paper. The remaining 54 stars, shared with the Disc Emission via a Bias-free Reconnaissance in IR and Sub-mm (DEBRIS) consortium and observed by them, and the combined full sample are studied in this paper. The incidence of debris discs per spectral type is analysed and put into context together with other parameters of the sample, like metallicity, rotation and activity, and age. Results. The subsample of 105 stars with d ≤ 15 pc containing 23 F, 33 G, and 49 K stars is complete for F stars, almost complete for G stars, and contains a substantial number of K stars from which we draw solid conclusions on objects of this spectral type. The incidence rates of debris discs per spectral type are 0.26^+0.21_-0.14 (6 objects with excesses out of 23 F stars), 0.21^+0.17_-0.11 (7 out of 33 G stars), and 0.20^+0.14_-0.09 (10 out of 49 K stars); the fraction for all three spectral types together is 0.22^+0.08_-0.07 (23 out of 105 stars). The uncertainties correspond to a 95% confidence level. The medians of the upper limits of L_dust/L_∗ for each spectral type are 7.8 × 10^-7 (F), 1.4 × 10^-6 (G), and 2.2 × 10^-6 (K); the lowest values are around 4.0 × 10^-7. The incidence of debris discs is similar for active (young) and inactive (old) stars. The fractional luminosity tends to drop with increasing age, as expected from collisional erosion of the debris belts.

The optical design of a far infrared imaging FTS for SPICA

This paper describes the optical design of the far infrared imaging spectrometer for the JAXA's SPICA mission. The SAFARI instrument, is a cryogenic imaging Fourier transform spectrometer (iFTS), designed to perform backgroundlimited spectroscopic and photometric imaging in the band 34-210 μm. The all-reflective optical system is highly modular and consists of three main modules; input optics module, interferometer module (FTS) and camera bay optics. A special study has been dedicated to the spectroscopic performance of the instrument, in which the spectral response and interference of the instrument have been modeled, as the FTS mechanism scans over the total desired OPD range.

Novos recetores de aniões baseados em homooxacalixarenos fluorescentes com potenciais aplicações biotecnológicas

A reação de condensação de fenóis para-substituídos com formaldeído em meio básico conduz à formação de calixarenos, compostos macrociclícos com cavidades que podem exibir diversos tamanhos e conformações. Estes compostos têm sido alvo de grande interesse devido à sua capacidade complexante e de transporte seletivo de iões e moléculas neutras, para além de serem usados como plataforma na obtenção de moléculas recetoras mais complexas. Nesta Tese de Mestrado realizou-se a síntese de novos recetores de aniões baseados em homooxacalixarenos fluorescentes contendo grupos ureia ou tioureia na coroa inferior e determinaram-se as suas propriedades complexantes relativamente a aniões com diversas geometrias. Primeiramente, efetuou-se a síntese de dois derivados dihomooxacalix[ 4]arenos (a partir do precursor p-terc-butildihomooxacalix[4]areno), compostos bidentados contendo grupos naftilureia (ou tioureia) na coroa inferior, através de um espaçador com quatro átomo de carbono, e de um derivado tri-substituído idêntico, a partir do precursor p-terc-butilhexahomotrioxacalix[3]areno. Os novos compostos foram caracterizados através das técnicas usuais e foi feita a sua análise conformacional por RMN. Em seguida investigaram-se as propriedades complexantes de aniões de diferentes geometrias (esférica, linear, trigonal planar e tetraédrica) com dois dos recetores sintetizados. Estes estudos foram realizados por RMN de protão e por espectroscopia de absorção no UV-Vis e de emissão em estado estacionário, utilizando três solventes diferentes (clorofórmio, diclorometano e acetonitrilo). Um terceiro recetor bidentado análogo já existente (dihomooxa fenilureia) foi também estudado por espectroscopia de absorção e emissão. De um modo geral, o derivado hexahomotrioxa trinaftilureia mostrou uma afinidade ligeiramente superior para com os aniões. Todos os recetores apresentaram as maiores constantes de associação para o anião fluoreto. Foram ainda feitos estudos de fotodegradação que indicaram a impossibilidade do uso do clorofórmio como solvente nos estudos por fluorescência.