Dissipation in planar resonant planetary systems

Close-in planetary systems detected by the Kepler mission present an excess of periods ratio that are just slightly larger than some low order resonant values. This feature occurs naturally when resonant couples undergo dissipation that damps the eccentricities. However, the resonant angles appear to librate at the end of the migration process, which is often believed to be an evidence that the systems remain in resonance. Here we provide an analytical model for the dissipation in resonant planetary systems valid for low eccentricities. We confirm that dissipation accounts for an excess of pairs that lie just aside from the nominal periods ratios, as observed by the Kepler mission. In addition, by a global analysis of the phase space of the problem, we demonstrate that these final pairs are non-resonant. Indeed, the separatrices that exist in the resonant systems disappear with the dissipation, and remains only a circulation of the orbits around a single elliptical fixed point. Furthermore, the apparent libration of the resonant angles can be explained using the classical secular averaging method. We show that this artifact is only due to the severe damping of the amplitudes of the eigenmodes in the secular motion.Comment: 18 pages, 20 figures, accepted to A&

Las poblaciones precolombinas que habitaron el sector central del valle de Vinchina entre el 900-950 y 1600-1650 d.C. (dto. General Lamadrid, La Rioja, Argentina)

En este trabajo se desarrollan algunos aspectos relevantes que hacen al patrón de instalación, el tamaño de la población, la complejidad socio-política y la cronología, de las sociedades Aguada y Sanagasta que habitaron el oeste riojano aproximadamente entre el 900 y 1650 de la era. La información presentada constituye una síntesis de los resultados alcanzados en los trabajos que, desde hacemás de una década, estamos realizando en la zona. Se comentan, además, algunos componentes del registro arqueológico que facilitan la comprensión de las sociedades en cuestión.This paper deals with some issues related to the settlement pattern, population size, sociopolitical complexity and chronology of the Aguada and Sanagasta societies. These societies occupied the west of La Rioja province between 900 and 1650 AD. The paper synthesizes the results of research we have been carrying out in the area for more than a decade. Also, some of the components which are useful in the understanding of the two societies are discussed.Sociedad Argentina de Antropologí

Penning ionization of doped helium nanodroplets following EUV excitation

Helium nanodroplets are widely used as a cold, weakly interacting matrix for spectroscopy of embedded species. In this work we excite or ionize doped He droplets using synchrotron radiation and study the effect onto the dopant atoms depending on their location inside the droplets (rare gases) or outside at the droplet surface (alkali metals). Using photoelectron-photoion coincidence imaging spectroscopy at variable photon energies (20-25 eV), we compare the rates of charge-transfer to Penning ionization of the dopants in the two cases. The surprising finding is that alkali metals, in contrast to the rare gases, are efficiently Penning ionized upon excitation of the (n=2)-bands of the host droplets. This indicates rapid migration of the excitation to the droplet surface, followed by relaxation, and eventually energy transfer to the alkali dopants

Dinámica de reciprocidad entre la comunidad y el arqueólogo

En este trabajo comentaremos algunas experiencias positivas y negativas que hemos tenido en distintas comunidades donde realizamos trabajos arqueológicos de campo. Estos tuvieron lugar en localidades del N.E. y N.O. riojano, concretamente en Anillaco y Villa Castelli. Un hecho fundamental que observamos es la importancia que tiene la aceptación del arqueólogo por parte de la comunidad, donde este va a desarrollar sus trabajos. Esto ocurre, cuando se visita reiteradamente el lugar y se entabla una relación de: confianza➙comunicación➙ intercambio de información. Dicho proceso crea una dinámica de enriquecimiento mutuo, donde el arqueólogo obtiene información y ayuda en el trabajo de campo; a su vez debido a ello tiene obligación de retribuir de alguna manera a la comunidad que lo recibe y ayuda.Facultad de Ciencias Naturales y Muse

Intermediate-mass black holes and ultraluminous X-ray sources in the Cartwheel ring galaxy

Chandra and XMM-Newton observations of the Cartwheel galaxy show ∼17 bright X-ray sources (≳5 × 1038erg s−1), all within the gas-rich outer ring. We explore the hypothesis that these X-ray sources are powered by intermediate-mass black holes (IMBHs) accreting gas or undergoing mass transfer from a stellar companion. To this purpose, we run N-body/smoothed particle hydrodynamics simulations of the galaxy interaction which might have led to the formation of Cartwheel, tracking the dynamical evolution of two different IMBH populations: halo and disc IMBHs. Halo IMBHs cannot account for the observed X-ray sources, as only a few of them cross the outer ring. Instead, more than half of the disc IMBHs are pulled in the outer ring as a consequence of the galaxy collision. However, also in the case of disc IMBHs, accretion from surrounding gas clouds cannot account for the high luminosities of the observed sources. Finally, more than 500 disc IMBHs are required to produce ≲15 X-ray sources via mass transfer from very young stellar companions. Such number of IMBHs is very large and implies extreme assumptions. Thus, the hypothesis that all the observed X-ray sources in Cartwheel are associated with IMBHs is hardly consistent with our simulations, even if it is still possible that IMBHs account for the few (≲1-5) brightest ultraluminous X-ray source

The Response of Test Masses to Gravitational Waves in the Coordinates of a Local Observer

The response of laser interferometers to gravitational waves has been calculated in a number of different ways, particularly in the transverse-traceless and the local Lorentz gauges. At first sight, it would appear that these calculations lead to different results when the separation between the test masses becomes comparable to the wavelength of the gravitational wave. In this paper this discrepancy is resolved. We describe the response of free test masses to plane gravitational waves in the coordinate frame of a local observer and show that it acquires contributions from three different effects: the displacement of the test masses, the apparent change in the photon velocity, and the variation in the clock speed of the local observer, all of which are induced by the gravitational wave. Only when taken together do these three effects represent a quantity which is translationally invariant. This translationally-invariant quantity is identical to the response function calculated in the transverse-traceless gauge. We thus resolve the well-known discrepancy between the two coordinates systems, and show that the results found in the coordinate frame of a local observer are valid for large separation between the masses.Comment: 25 pages, 3 figures, Latex2

Defining the Substrate Spectrum of the TIM22 Complex Identifies Pyruvate Carrier Subunits as Unconventional Cargos

Mitochondria carrier proteins, which possess six transmembrane spans (TM), are transported by the TIM22 complex. By using a quantitative proteomic approach, Gomkale and Cruz-Zaragoza et al. reveal subunits of the mitochondrial pyruvate carrier (MPC) that possess two or three TMs as unexpected substrates of the carrier pathway

Coherently averaged dual-comb spectroscopy with a low-noise and high-power free-running gigahertz dual-comb laser

We present a new type of dual optical frequency comb source capable of scaling applications to high measurement speeds while combining high average power, ultra-low noise operation, and a compact setup. Our approach is based on a diode-pumped solid-state laser cavity which includes an intracavity biprism operated at Brewster angle to generate two spatially-separated modes with highly correlated properties. The 15-cm-long cavity uses an Yb:CALGO crystal and a SESAM as an end mirror to generate more than 3 W average power per comb, below 80 fs pulse duration, a repetition rate of 1.03 GHz, and a continuously tunable repetition rate difference up to 27 kHz. We carefully investigate the coherence properties of the dual-comb by a series of heterodyne measurements, revealing several important features: (1) ultra-low jitter on the uncorrelated part of the timing noise; (2) the radio frequency comb lines of the interferograms are fully resolved in free-running operation; (3) we validate that through a simple measurement of the interferograms we can determine the fluctuations of the phase of all the radio frequency comb lines; (4) this phase information is used in a post-processing routine to perform coherently averaged dual-comb spectroscopy of acetylene (C2H2) over long timescales. Our results represent a powerful and general approach to dual-comb applications by combining low noise and high power operation directly from a highly compact laser oscillator