Kn 26, a New Quadrupolar Planetary Nebula

Once classified as an emission line source, the planetary nebula (PN) nature of the source Kn 26 has been only recently recognized in digital sky surveys. To investigate the spectral properties and spatio-kinematical structure of Kn 26, we have obtained high spatial-resolution optical and near-IR narrow-band images, high-dispersion long-slit echelle spectra, and intermediate-resolution spectroscopic observations. The new data reveal an hourglass morphology typical of bipolar PNe. A detailed analysis of its morphology and kinematics discloses the presence of a second pair of bipolar lobes, making Kn 26 a new member of the subclass of quadrupolar PNe. The time-lap between the ejection of the two pairs of bipolar lobes is much smaller than their dynamical ages, implying a rapid change of the preferential direction of the central engine. The chemical composition of Kn 26 is particularly unusual among PNe, with a low N/O ratio (as of type II PNe) and a high helium abundance (as of type I PNe), although not atypical among symbiotic stars. Such an anomalous chemical composition may have resulted from the curtail of the time in the Asymptotic Giant Branch by the evolution of the progenitor star through a common envelope phase.Comment: 9 pages, 5 figures, accepted for publication in A&

Vector meson quasinormal modes in a finite-temperature AdS/QCD model

We study the spectrum of vector mesons in a finite temperature plasma. The plasma is holographically described by a black hole AdS/QCD model. We compute the boundary retarded Green's function using AdS/CFT prescriptions. The corresponding thermal spectral functions show quasiparticle peaks at low temperatures. Then we calculate the quasinormal modes of vector mesons in the soft-wall black hole geometry and analyse their temperature and momentum dependences.Comment: 27 pages, 9 figure

CRIRES-VLT high-resolution spectro-astrometry as a tool in the search of small structures at the cores of Planetary Nebulae

The onset of the asymmetry in planetary nebulae (PNe) occurs during the short transition between the end of the asymptotic giant branch (AGB) phase and the beginning of the PN phase. Sources in this transition phase are compact and emit intensely in infrared wavelengths, making high spatial resolution observations in the infrared mandatory to investigate the shaping process of PNe. Interferometric VLTI IR observations have revealed compelling evidence of disks at the cores of PNe, but the limited sensitivity, strong observational constraints, and limited spatial coverage place severe limits on the universal use of this technique. Inspired by the successful detection of proto-planetary disks using spectro-astrometric observations, we apply here for the first time this technique to search for sub-arcsecond structures in PNe. Our exploratory study using CRIRES (CRyogenic high-resolution Infra-Red Echelle Spectrograph) commissioning data of the proto-PN IRAS 17516-2525 and the young PN SwSt 1 has revealed small-sized structures after the spectro-astrometric analysis of the two sources. In IRAS 17516-2525, the spectro-astrometric signal has a size of only 12 mas, as detected in the Brackett-gamma line, whereas the structures found in SwSt 1 have sizes of 230 mas in the [Fe III] line and 130 mas in the Brackett-gamma line. The spectroscopic observations required to perform spectro-astrometry of sources in the transition towards the PN phase are less time consuming and much more sensitive than VLTI IR observations. The results presented here open a new window in the search of the small-sized collimating agents that shape the complex morphologies of extremely axisymmetric PNe.Comment: 6 pages, 4 figure

VISIR-VLT Images of the Water Maser Emitting Planetary Nebula K 3-35

K3-35 is an extremely young bipolar planetary nebula that contains a precessing bipolar jet and a small (radius 80 AU) water maser equatorial ring. We have obtained VISIR- VLT images of K 3-35 in the PAH1 ({\lambda}=8.6 {\mu}m), [S iv] ({\lambda}=10.6 {\mu}m), and SiC ({\lambda}=11.85 {\mu}m) filters to analize the mid-IR morphology and the temperature structure of its dust emission. The images show the innermost nebular regions undetected at optical wavelegths and the precessing bipolar jets. The temperature map shows variations in the temperature in the equatorial zone and in regions associated to its jets.Comment: 2 pages, 2 figures, 283 IAU Symp. Planetary Nebulae an Eye to the Futur

A new species of \u3cem\u3eAnanteris\u3c/em\u3e (Scorpiones: Buthidae) from Panama

A new buthid species belonging to the genus Ananteris Thorell, 1891 is herein described from Panama Oeste Province, Panama. This is the second Ananteris species known from this Central American country and clearly differs from Ananteris platnicki Lourenço, 1993, distributed in Costa Rica and Panama, by its smaller size and male having a different hemispermatophore and telson similar to that of the female

Predation of \u3cem\u3eAnanteris\u3c/em\u3e spp. (Scorpiones: Buthidae) by ants and a social wasp (Hymenoptera: Formicidae, Vespidae) in Panama, Central America

Two events of predation on Ananteris spp. were observed in the Parque Nacional Darién, Darién Province, Panama. The first case involved the social wasp Agelaia centralis (Cameron, 1907) (Vespidae); the second one, a ponerine ant Leptogenys cf. cuneata Lattke, 2011 (Formicidae). This is the first time that predation by a social wasp on a scorpion is observed. They also represent the first recorded predators for Panamanian Ananteris species