Extrasolar Planets in Mean-Motion Resonance: Apses Alignment and Asymmetric Stationary Solutions

In recent years several pairs of extrasolar planets have been discovered in the vicinity of mean-motion commensurabilities. In some cases, such as the Gliese 876 system, the planets seem to be trapped in a stationary solution, the system exhibiting a simultaneous libration of the resonant angle theta_1 = 2 lambda_2 - lambda_1 - varpi_1 and of the relative position of the pericenters. In this paper we analyze the existence and location of these stable solutions, for the 2/1 and 3/1 resonances, as function of the masses and orbital elements of both planets. This is undertaken via an analytical model for the resonant Hamiltonian function. The results are compared with those of numerical simulations of the exact equations. In the 2/1 commensurability, we show the existence of three principal families of stationary solutions: (i) aligned orbits, in which theta_1 and varpi_1 - varpi_2 both librate around zero, (ii) anti-aligned orbits, in which theta_1=0 and the difference in pericenter is 180 degrees, and (iii) asymmetric stationary solutions, where both the resonant angle and varpi_1 - varpi_2 are constants with values different of 0 or 180 degrees. Each family exists in a different domain of values of the mass ratio and eccentricities of both planets. Similar results are also found in the 3/1 resonance. We discuss the application of these results to the extrasolar planetary systems and develop a chart of possible planetary orbits with apsidal corotation. We estimate, also, the maximum planetary masses in order that the stationary solutions are dynamically stable.Comment: 25 pages, 10 figures. Submitted to Ap

Origin of the heavy elements in HD 140283. Measurement of europium abundance

HD 140283 is a nearby (V=7.7) subgiant metal-poor star, extensively analysed in the literature. Although many spectra have been obtained for this star, none showed a signal-to-noise (S/N) ratio high enough to enable a very accurate derivation of abundances from weak lines. The detection of europium proves that the neutron-capture elements in this star originate in the r-process, and not in the s-process, as recently claimed in the literature. Based on the OSMARCS 1D LTE atmospheric model and with a consistent approach based on the spectrum synthesis code Turbospectrum, we measured the europium lines at 4129 {\AA} and 4205 {\AA}, taking into account the hyperfine structure of the transitions. The spectrum, obtained with a long exposure time of seven hours at the Canada-France-Hawaii Telescope (CFHT), has a resolving power of 81000 and a S/N ratio of 800 at 4100 {\AA}. We were able to determine the abundance A(Eu)=-2.35 dex, compatible with the value predicted for the europium from the r-process. The abundance ratio [Eu/Ba]=+0.58 dex agrees with the trend observed in metal-poor stars and is also compatible with a strong r-process contribution to the origin of the neutron-capture elements in HD 140283.Comment: 10 pages, 7 figures. To be published in A\&

Electronic Phase Separation Transition as the Origin of the Superconductivity and the Pseudogap Phase of Cuprates

We propose a new phase of matter, an electronic phase separation transition that starts near the upper pseudogap and segregates the holes into high and low density domains. The Cahn-Hilliard approach is used to follow quantitatively this second order transition. The resulting grain boundary potential confines the charge in domains and favors the development of intragrain superconducting amplitudes. The zero resistivity transition arises only when the intergrain Josephson coupling $E_J$ is of the order of the thermal energy and phase locking among the superconducting grains takes place. We show that this approach explains the pseudogap and superconducting phases in a natural way and reproduces some recent scanning tunneling microscopy dataComment: 4 pages and 5 eps fig

Ongoing Mass Transfer in the Interacting Galaxy Pair NGC 1409/10

I present two-band HST STIS imaging, and WIYN spectral mapping, of ongoing mass transfer in the interacting galaxy pair NGC 1409/10 (where NGC 1410 is the Seyfert galaxy also catalogued as III Zw 55). Archival snapshot WFPC2 imaging from the survey by Malkan et al. showed a dust feature stretching between the galaxies, apparently being captured by NGC 1409. The new images allow estimates of the mass being transferred and rate of transfer. An absorption lane typically 0.25" (100 pc) wide with a representative optical depth tau_B = 0.2 cuts across the spiral structure of NGC 1410, crosses the 7-kpc projected space between the nuclei, wraps in front of and, at the limits of detection, behind NGC 1409, and becomes a denser (tau_B = 0.4) polar feature around the core of NGC 1409. Combination of extinction data in two passbands allows a crude three-dimensional recovery of the dust structure, supporting the front/back geometry derived from colors and extinction estimates. The whole feature contains of order $10^6$ solar masses in dust, implying about 2x10^7 solar masses of gas, requiring a mass transfer rate averaging ~1 solar mass per year unless we are particularly unlucky in viewing angle. Curiously, this demonstrable case of mass transfer seems to be independent of the occurrence of a Seyfert nucleus, since the Seyfert galaxy in this pair is the donor of the material. Likewise, the recipient shows no signs of recent star formation from incoming gas, although NGC 1410 has numerous luminous young star clusters and widespread H-alpha emission.Comment: 27 pages, 9 figures. Accepted for the Astronomical Journal, March 200

Statistical fluctuations of the parametric derivative of the transmission and reflection coefficients in absorbing chaotic cavities

Motivated by recent theoretical and experimental works, we study the statistical fluctuations of the parametric derivative of the transmission T and reflection R coefficients in ballistic chaotic cavities in the presence of absorption. Analytical results for the variance of the parametric derivative of T and R, with and without time-reversal symmetry, are obtained for both asymmetric and left-right symmetric cavities. These results are valid for arbitrary number of channels, in completely agreement with the one channel case in the absence of absorption studied in the literature.Comment: Modified version as accepted in PR