New Galactic star clusters discovered in the VVV survey

Context. VISTA Variables in the Via Lactea (VVV) is one of the six ESO Public Surveys operating on the new 4-m Visible and Infrared Survey Telescope for Astronomy (VISTA). VVV is scanning the Milky Way bulge and an adjacent section of the disk, where star formation activity is high. One of the principal goals of the VVV Survey is to find new star clusters of different ages. Aims. In order to trace the early epochs of star cluster formation we concentrated our search in the directions to those of known star formation regions, masers, radio, and infrared sources. Methods. The disk area covered by VVV was visually inspected using the pipeline processed and calibrated K(S)-band tile images for stellar over-densities. Subsequently, we examined the composite JHK(S) and ZJK(S) color images of each candidate. PSF photometry of 15 x 15 arcmin fields centered on the candidates was then performed on the Cambridge Astronomy Survey Unit reduced images. After statistical field-star decontamination, color-magnitude and color-color diagrams were constructed and analyzed. Results. We report the discovery of 96 new infrared open clusters and stellar groups. Most of the new cluster candidates are faint and compact (with small angular sizes), highly reddened, and younger than 5 Myr. For relatively well populated cluster candidates we derived their fundamental parameters such as reddening, distance, and age by fitting the solar-metallicity Padova isochrones to the color-magnitude diagrams.

Il viaggio di Faust in Italia : percorsi di ricezione di un mito moderno

La tesi descrive il fenomeno di ricezione del mito faustiano all'interno della tradizione letteraria italiana di Otto e Novecento (1808-1945) nel suo sviluppo diacronico, individuando i nodi processuali emergenti ritenuti sistematici accanto alle tipologie predominanti della risposta testuale e alle più proficue rifunzionalizzazioni letterarie. La storia del mito di Faust è stata considerata aristotelicamente nella sua natura complessa ed evolutiva di fabula rinarrata, e di volta in volta risemantizzata in nuovi sistemi di valori, estetici e ideologici. Ma soprattutto in nuovi sistemi testuali. Scopo primario è stato infatti quello di comprendere come il mito di Faust sia entrato dentro alla cultura letteraria italiana e come abbia agito al suo interno, interferendo con essa. Naturalmente lo scambio e gli sviluppi hanno investito in modo reciproco e la tradizione accogliente e il mito stesso, producendo un allargamento esegetico delle sue possibilità semantiche: è infatti emersa una storia testuale che tematizza nel tempo il medesimo mito lungo assi interpretative anche estremamente divergenti. La ricerca ha portato alla scoperta di una ricca testualità rimossa dal canone della storia della letteratura italiana, anche se spesso prevalgono i testi-documento sui testi esteticamente più validi e significativi in sé; si tratta di una testualità talmente quantitativamente ricca da invitare ad un ripensamento qualitativo del fenomeno generale. Il mito di Faust, per due secoli percepito dalla critica dominante come distante ed estraneo alla cultura letteraria italiana, è invece riuscito ad entrare nella tradizione letteraria italiana, anche se attraverso modalità molto controverse: in linea di massima è potuto passare dal canone statico al canone dinamico laddove ha saputo influenzare e stimolare nuove vie significative di sviluppo formale. Il confronto della cultura letteraria italiana con il mito di Faust è stato in effetti caratterizzato subito da un doppio movimento discratico di rifiuto e dialogo. Il principale fattore di rifiuto è stato di carattere culturale: la difficoltà ad accettare un equilibrio fatto non di antitesi risolte in una sintesi ma di polarità aperte, irrisolte, in perpetuo bilanciamento, anche a livello formale reso in una tragedia franta in scene apparentemente autonome, divisa in due parti così diverse e chiusa da un lieto fine, mal si confaceva ai diffusi canoni classicisti di equilibrio formale, nonché alle esigenze romantiche di poesia moralmente chiara nel suo messaggio. Da qui le diffuse accuse di scarsa chiarezza e ambiguità morale, che andavano direttamente ad incontrarsi e sommarsi con i pregiudizi più propriamente teologico- religiosi di estraneità a quel mito nato come saga luterana dichiaratamente anti-papale. La condanna di carattere moralistico-cattolico risulta nei fatti propria più di certa cultura che non del largo pubblico che invece nel corso dell'Ottocento dimostra di gradire le versioni per musica e balletto di argomento faustiano, per quanto semplificata ed edulcorate rispetto alla leggenda originaria così come rispetto alla tragedia goethiana. Rispetto a tutti questi elementi di resistenza e rifiuto l'opera Mefistofele di Boito si presenta come snodo di opposizione consapevole e riferimento duraturo d'interrogazione critica. La principale linea di avvicinamento invece tra la cultura letteraria italiana e il mito di Faust resta quella del parallelo, già ideato dagli stessi intellettuali tedeschi d'inizio Ottocento, con l'opera ritenuta massima nel nuovo canone nazionale italiano da fine Settecento ad oggi: la Divina Commedia. Tanta critica, almeno fino alla metà del XX secolo, si rifà più o meno esplicitamente a questo parallelo pregiudiziale e testualmente piuttosto infondato ma molto produttivo, come si è attestato, a livello creativo. Questa ricostruzione ha voluto nel suo complesso dimostrare sul campo il valore di questo macrotesto faustiano come una delle vie maestre della dialettica tra tradizione e modernità, ancor più significativa nell'ambito di una cultura letteraria come quella italiana che, dopo l'estinguersi della sua centralità in epoca rinascimentale, si è rivelata particolarmente resistente al dialogo con le altre letterature fino al pieno Novecento.

Isolario in Versi

Kyseessä on Egeanmeren saarien kartasto, jossa annetaan sonetin muodossa ohjeet Egeanmeren purjehdukseen. Atlaksessa on 49 puupiirroskarttaa saarista. Meren karit on merkitty symbolein – ristillä ja pisteillä, joita käytetään vielä tänäkin päivänä. Tekijää, venetsialaista Bartolomeo da li Sonettia, ei tarkemmin tunneta. Hänen nimensä on ilmaistu teoksen toisessa sonetissa: "Per aprobar questa opereta fata per me bartolomeo da li sonetti intendo de monstrar con veri effetti quanto che londa egeia abia cerchatta..." Teosta tunnetaan alle 50 kappaletta maailmassa, ja kaikki kappaleet ovat keskenään hiukan erilaisia. Teos kuuluu A. E. Nordenskiöldin kokoelmaan, joka vanhan kartografisen ja maantieteellisen kirjallisuuden osalta on ainutlaatuinen ja kuuluu ainoana suomalaisena kohteena henkisen kulttuuriperinnön Memory of the World -rekisteriin. Nordenskiöld on ostanut teoksen joulukuussa 1892 Hoeplilta Milanosta.

PLANETARY NEBULAE IN THE INNER MILKY WAY II: THE BULGE-DISK TRANSITION

In this work, a sample of planetary nebulae located in the inner-disk and bulge of the Galaxy is used in order to find the galactocentric distance which better separates these two populations, from the point of view of abundances. Statistical distance scales are used to study the distribution of abundances across the disk-bulge interface. A Kolmogorov-Smirnov test is used to find the distance at which the chemical properties of these regions better separate. The results of the statistical analysis indicate that, on the average, the inner population has lower abundances than the outer. Additionally, for the a-element abundances, the inner population does not follow the disk radial gradient towards the galactic center. Based on our results, we suggest a bulge-disk interface at 1.5 kpc, marking the transition between the bulge and inner-disk of the Galaxy as defined by the intermediate mass population.

PLANETARY NEBULAE IN THE INNER MILKY WAY: NEW ABUNDANCES

The study of planetary nebulae in the inner-disk and bulge gives important information on the chemical abundances of elements such as He, N, O, Ar, Ne, and on the evolution of these abundances, which is associated with the evolution of intermediate-mass stars and the chemical evolution of time Galaxy. We present accurate abundances of the elements He, N, 5, 0, Ar, and Ne for a sample of 54 planetary nebulae located towards the bulge of the Galaxy, for 33 of which the abundances are derived here for the first time. The abundances are obtained based on observations in the optical domain made at the National Laboratory for Astrophysics (LNA, Brazil). The data show a good agreement; with other results in the literature, in the sense that the distribution of the abundances is similar to that of those works.

Advanced functionality for radio analysis in the Offline software framework of the Pierre Auger Observatory

The advent of the Auger Engineering Radio Array (AERA) necessitates the development of a powerful framework for the analysis of radio measurements of cosmic ray air showers. As AERA performs ""radio-hybrid"" measurements of air shower radio emission in coincidence with the surface particle detectors and fluorescence telescopes of the Pierre Auger Observatory, the radio analysis functionality had to be incorporated in the existing hybrid analysis solutions for fluorescence and surface detector data. This goal has been achieved in a natural way by extending the existing Auger Offline software framework with radio functionality. In this article, we lay out the design, highlights and features of the radio extension implemented in the Auger Offline framework. Its functionality has achieved a high degree of sophistication and offers advanced features such as vectorial reconstruction of the electric field, advanced signal processing algorithms, a transparent and efficient handling of FFTs, a very detailed simulation of detector effects, and the read-in of multiple data formats including data from various radio simulation codes. The source code of this radio functionality can be made available to interested parties on request. (C) 2011 Elsevier B.V. All rights reserved.

Search for first harmonic modulation in the right ascension distribution of cosmic rays detected at the Pierre Auger Observatory

We present the results of searches for dipolar-type anisotropies in different energy ranges above 2.5 x 10(17) eV with the surface detector array of the Pierre Auger Observatory, reporting on both the phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99% C.L. for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations. (C) 2011 Elsevier B.V. All rights reserved.

MASSLESS PARTICLE CREATION IN A F(R) ACCELERATING UNIVERSE

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A cyclic bipolar wind in the interacting binary V 393 Scorpii

V393 Scorpii is a double periodic variable characterized by a relatively stable non-orbital photometric cycle of 253 d. Mennickent et al. argue for the presence of a massive optically thick disc around the more massive B-type component and describe the evolutionary stage of the system. In this paper, we analyse the behaviour of the main spectroscopic optical lines during the long non-orbital photometric cycle. We study the radial velocity of the donor determining its orbital elements and find a small but significant orbital eccentricity (e = 0.04). The donor spectral features are modelled and removed from the spectrum at every observing epoch using the light-curve model given by Mennickent et al. We find that the line emission is larger during eclipses and mostly comes from a bipolar wind. We also find that the long cycle is explained in terms of a modulation of the wind strength; the wind has a larger line and continuum emissivity at the high state. We report the discovery of highly variable chromospheric emission in the donor, as revealed by the Doppler maps of the emission lines Mg II 4481 and C I 6588. We discuss notable and some novel spectroscopic features like discrete absorption components, especially visible at blue depressed O I 7773 absorption wings during the second half-cycle, Balmer double emission with V/R curves showing 'Z-type' and 'S-type' excursions around secondary and main eclipses, respectively, and H beta emission wings extending up to +/- 2000 km s(-1). We also discuss possible causes for these phenomena and for their modulations with the long cycle.

VVV DR1: The first data release of the Milky Way bulge and southern plane from the near-infrared ESO public survey VISTA variables in the Via Lactea

Context. The ESO public survey VISTA variables in the Via Lactea (VVV) started in 2010. VVV targets 562 sq. deg in the Galactic bulge and an adjacent plane region and is expected to run for about five years. Aims. We describe the progress of the survey observations in the first observing season, the observing strategy, and quality of the data obtained. Methods. The observations are carried out on the 4-m VISTA telescope in the ZYJHK(s) filters. In addition to the multi-band imaging the variability monitoring campaign in the K-s filter has started. Data reduction is carried out using the pipeline at the Cambridge Astronomical Survey Unit. The photometric and astrometric calibration is performed via the numerous 2MASS sources observed in each pointing. Results. The first data release contains the aperture photometry and astrometric catalogues for 348 individual pointings in the ZYJHK(s) filters taken in the 2010 observing season. The typical image quality is similar to 0 ''.9-1 ''.0. The stringent photometric and image quality requirements of the survey are satisfied in 100% of the JHK(s) images in the disk area and 90% of the JHK(s) images in the bulge area. The completeness in the Z and Y images is 84% in the disk, and 40% in the bulge. The first season catalogues contain 1.28 x 10(8) stellar sources in the bulge and 1.68 x 10(8) in the disk area detected in at least one of the photometric bands. The combined, multi-band catalogues contain more than 1.63 x 10(8) stellar sources. About 10% of these are double detections because of overlapping adjacent pointings. These overlapping multiple detections are used to characterise the quality of the data. The images in the JHK(s) bands extend typically similar to 4 mag deeper than 2MASS. The magnitude limit and photometric quality depend strongly on crowding in the inner Galactic regions. The astrometry for K-s = 15-18 mag has rms similar to 35-175 mas. Conclusions. The VVV Survey data products offer a unique dataset to map the stellar populations in the Galactic bulge and the adjacent plane and provide an exciting new tool for the study of the structure, content, and star-formation history of our Galaxy, as well as for investigations of the newly discovered star clusters, star-forming regions in the disk, high proper motion stars, asteroids, planetary nebulae, and other interesting objects.

OXYGEN ABUNDANCES IN LOW- AND HIGH-alpha FIELD HALO STARS AND THE DISCOVERY OF TWO FIELD STARS BORN IN GLOBULAR CLUSTERS

Oxygen abundances of 67 dwarf stars in the metallicity range -1.6 < [Fe/H] < -0.4 are derived from a non-LTE analysis of the 777 nm O I triplet lines. These stars have precise atmospheric parameters measured by Nissen and Schuster, who find that they separate into three groups based on their kinematics and alpha-element (Mg, Si, Ca, Ti) abundances: thick disk, high-alpha halo, and low-alpha halo. We find the oxygen abundance trends of thick-disk and high-alpha halo stars very similar. The low-alpha stars show a larger star-to-star scatter in [O/Fe] at a given [Fe/H] and have systematically lower oxygen abundances compared to the other two groups. Thus, we find the behavior of oxygen abundances in these groups of stars similar to that of the a elements. We use previously published oxygen abundance data of disk and very metal-poor halo stars to present an overall view (-2.3 < [Fe/H] < +0.3) of oxygen abundance trends of stars in the solar neighborhood. Two field halo dwarf stars stand out in their O and Na abundances. Both G53-41 and G150-40 have very low oxygen and very high sodium abundances, which are key signatures of the abundance anomalies observed in globular cluster (GC) stars. Therefore, they are likely field halo stars born in GCs. If true, we estimate that at least 3% +/- 2% of the local field metal-poor star population was born in GCs.

Stochastic gravito-inertial modes discovered by CoRoT in the hot Be star HD51452

Context. Be stars are rapidly rotating stars with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the kappa-mechanism, i.e. an effect of the opacity of iron-peak elements in the envelope of the star. In the Milky Way, p-modes are observed in stars that are hotter than or equal to the B3 spectral type, while g-modes are observed at the B2 spectral type and cooler. Aims. We observed a B0IVe star, HD51452, with the high-precision, high-cadence photometric CoRoT satellite and high-resolution, ground-based HARPS and SOPHIE spectrographs to study its pulsations in great detail. We also used the lower resolution spectra available in the BeSS database. Methods. We analyzed the CoRoT and spectroscopic data with several methods: CLEAN-NG, FREQFIND, and a sliding window method. We also analyzed spectral quantities, such as the violet over red (V/R) emission variations, to obtain information about the variation in the circumstellar environment. We calculated a stellar structure model with the ESTER code to test the various interpretation of the results. Results. We detect 189 frequencies of variations in the CoRoT light curve in the range between 0 and 4.5 c d(-1). The main frequencies are also recovered in the spectroscopic data. In particular we find that HD51452 undergoes gravito-inertial modes that are not in the domain of those excited by the kappa-mechanism. We propose that these are stochastic modes excited in the convective zones and that at least some of them are a multiplet of r-modes (i.e. subinertial modes mainly driven by the Coriolis acceleration). Stochastically excited gravito-inertial modes had never been observed in any star, and theory predicted that their very low amplitudes would be undetectable even with CoRoT. We suggest that the amplitudes are enhanced in HD51452 because of the very rapid stellar rotation. In addition, we find that the amplitude variations of these modes are related to the occurrence of minor outbursts. Conclusions. Thanks to CoRoT data, we have detected a new kind of pulsations in HD51452, which are stochastically excited gravito-inertial modes, probably due to its very rapid rotation. These modes are probably also present in other rapidly rotating hot Be stars.