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THE CHANDRA PLANETARY NEBULA SURVEY (CHANPLANS). II. X-RAY EMISSION FROM COMPACT PLANETARY NEBULAE

Titulo: 
THE CHANDRA PLANETARY NEBULA SURVEY (CHANPLANS). II. X-RAY EMISSION FROM COMPACT PLANETARY NEBULAE
Autores: 
Freeman, M; Montez, R; Kastner, JH; Balick, B; Frew, DJ; Jones, D; Miszalski, B; Sahai, R; Blackman, E; Chu, YH; De Marco, O; Frank, A; Guerrero, MA; Lopez, JA; Zijlstra, A; Bujarrabal, V; Corradi, RLM; Nordhaus, J; Parker, QA; Sandin, C; Schonberner, D; Soker, N; Sokoloski, JL; Steffen, M; Toala, JA; Ueta, T; Villaver, E
Resumen: 
We present results from the most recent set of observations obtained as part of the Chandra X-ray observatory Planetary Nebula Survey (ChanPlaNS), the first comprehensive X-ray survey of planetary nebulae (PNe) in the solar neighborhood (i.e., within similar to 1.5 kpc of the Sun). The survey is designed to place constraints on the frequency of appearance and range of X-ray spectral characteristics of X-ray-emitting PN central stars and the evolutionary timescales of wind-shock-heated bubbles within PNe. ChanPlaNS began with a combined Cycle 12 and archive Chandra survey of 35 PNe. ChanPlaNS continued via a Chandra Cycle 14 Large Program which targeted all (24) remaining known compact (R-neb less than or similar to 0.4 pc), young PNe that lie within similar to 1.5 kpc. Results from these Cycle 14 observations include first-time X-ray detections of hot bubbles within NGC 1501, 3918, 6153, and 6369, and point sources in HbDs 1, NGC 6337, and Sp 1. The addition of the Cycle 14 results brings the overall ChanPlaNS diffuse X-ray detection rate to similar to 27% and the point source detection rate to similar to 36%. It has become clearer that diffuse X-ray emission is associated with young (less than or similar to 5 x 10(3) yr), and likewise compact (R-neb less than or similar to 0.15 pc), PNe with closed structures and high central electron densities (n(e) greater than or similar to 1000 cm(-3)), and is rarely associated with PNe that show H-2 emission and/or pronounced butterfly structures. Hb 5 is one such exception of a PN with a butterfly structure that hosts diffuse X-ray emission. Additionally, two of the five new diffuse X-ray detections (NGC 1501 and NGC 6369) host [WR]-type central stars, supporting the hypothesis that PNe with central stars of [WR]-type are likely to display diffuse X-ray emission.
Autor principal: 
Freeman, M
Autor/es del IAA: 
Guerrero, M. A.; Toala, J. A.
DOI: 
10.1088/0004-637X/794/2/99
Revista: 
ASTROPHYSICAL JOURNAL
Fecha de publicación: 
2014/10/20
Volumen: 
794
Issue: 
2
Tipo de documento: 
Article
Palabras clave: 
binaries: general; planetary nebulae: individual (NGC 1501, NGC 3918, NGC 6153, NGC 6369, HbDs 1, NGC 6337, Sp 1); stars: AGB and post-AGB
Número de artículo: 
99

H2O maser emission associated with the planetary nebula IRAS 16333-4807

Titulo: 
H2O maser emission associated with the planetary nebula IRAS 16333-4807
Autores: 
Uscanga, L; Gomez, JF; Miranda, LF; Boumis, P; Suarez, O; Torrelles, JM; Anglada, G; Tafoya, D
Resumen: 
We present simultaneous observations of H2O maser emission and radio continuum at 1.3 cm carried out with the Australia Telescope Compact Array towards two sources, IRAS 16333-4807 and IRAS 12405-6219, catalogued as planetary nebula (PN) candidates, and where single-dish detections of H2O masers have been previously reported. Our goal was to unambiguously confirm the spatial association of the H2O masers with these two PN candidates. We detected and mapped H2O maser emission in both fields, but only in IRAS 16333-4807 the maser emission is spatially associated with the radio continuum emission. The properties of IRAS 16333-4807 provide strong support for the PN nature of the object, hereby confirming it as the fifth known case of an H2O maser-emitting PN. This source is bipolar, like the other four known H2O maser-emitting PNe, indicating that these sources might pertain to a usual, but short phase in the evolution of bipolar PNe. In IRAS 12405-6219, the H2O maser and radio continuum emission are not associated with each other and, in addition, the available data indicate that this source is an H II region rather than a PN.
Autor principal: 
Uscanga, L
Autor/es del IAA: 
Gomez, J. F.; Miranda, L. F.; Anglada, G.
DOI: 
10.1093/mnras/stu1468
Revista: 
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Fecha de publicación: 
2014/10/11
Volumen: 
444
Issue: 
1
Páginas: 
217-221
Tipo de documento: 
Article
Palabras clave: 
masers; planetary nebulae: general; planetary nebulae: individual: IRAS 16333-4807

GRB 130925A: an ultralong gamma ray burst with a dust-echo afterglow, and implications for the origin of the ultralong GRBs

Titulo: 
GRB 130925A: an ultralong gamma ray burst with a dust-echo afterglow, and implications for the origin of the ultralong GRBs
Autores: 
Evans, PA; Willingale, R; Osborne, JP; O'Brien, PT; Tanvir, NR; Frederiks, DD; Pal'shin, VD; Svinkin, DS; Lien, A; Cummings, J; Xiong, S; Zhang, BB; Gotz, D; Savchenko, V; Negoro, H; Nakahira, S; Suzuki, K; Wiersema, K; Starling, RLC; Castro-Tirado, AJ; Beardmore, AP; Sanchez-Ramirez, R; Gorosabel, J; Jeong, S; Kennea, JA; Burrows, DN; Gehrels, N
Resumen: 
GRB 130925A was an unusual gamma ray burst (GRB), consisting of three distinct episodes of high-energy emission spanning similar to 20 ks, making it a member of the proposed category of 'ultralong' bursts. It was also unusual in that its late-time X-ray emission observed by Swift was very soft, and showed a strong hard-to-soft spectral evolution with time. This evolution, rarely seen in GRB afterglows, can be well modelled as the dust-scattered echo of the prompt emission, with stringent limits on the contribution from the normal afterglow (i.e. external shock) emission. We consider and reject the possibility that GRB 130925A was some form of tidal disruption event, and instead show that if the circumburst density around GRB 130925A is low, the long duration of the burst and faint external shock emission are naturally explained. Indeed, we suggest that the ultralong GRBs as a class can be explained as those with low circumburst densities, such that the deceleration time (at which point the material ejected from the nascent black hole is decelerated by the circumburst medium) is similar to 20 ks, as opposed to a few hundred seconds for the normal long GRBs. The increased deceleration radius means that more of the ejected shells can interact before reaching the external shock, naturally explaining both the increased duration of GRB 130925A, the duration of its prompt pulses, and the fainter-than-normal afterglow.
Autor principal: 
Evans, PA
Autor/es del IAA: 
Castro-Tirado, A. J.; Sanchez-Ramirez, R.; Gorosabel, J.; Jeong, S.
DOI: 
10.1093/mnras/stu1459
Revista: 
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Fecha de publicación: 
2014/10/11
Volumen: 
444
Issue: 
1
Páginas: 
250-267
Tipo de documento: 
Article
Palabras clave: 
gamma-ray burst: general; gamma-ray burst, individual: GRB 130925A

A NEW METHOD TO OBTAIN THE BROAD LINE REGION SIZE OF HIGH REDSHIFT QUASARS

Titulo: 
A NEW METHOD TO OBTAIN THE BROAD LINE REGION SIZE OF HIGH REDSHIFT QUASARS
Autores: 
Negrete, CA; Dultzin, D; Marziani, P; Sulentic, JW
Resumen: 
We present high signal-to-noise ratio UV spectra for eight quasars at z similar to 3 obtained with Very Large Telescope/FORS. The spectra enable us to analyze in detail the strong and weak emission features in the rest frame range 1300-2000 angstrom of each source (CIII] lambda 1909, Si III] lambda 1892, Al III lambda 1860, Si II lambda 1814, C IV lambda 1549 and blended Si IV lambda 1397+O IV] lambda 1402). The flux ratios Al III lambda 1860/Si III] lambda 1892, CIV lambda 1549/Al III lambda 1860, Si IV lambda 1397+O IV] lambda 1402/Si III lambda 1892 and Si IV lambda 1397+O IV] lambda 1402/C IV lambda 1549 strongly constrain ionizing photon flux and metallicity through the use of diagnostic maps built from CLOUDY simulations. The radius of the broad line region is then derived from the ionizing photon flux applying the definition of the ionization parameter. The rBLR estimate and the width of a virial component isolated in prominent UV lines yields an estimate of black hole mass. We compare our results with previous estimates obtained from the rBLR-luminosity correlation customarily employed to estimate the black hole masses of high redshift quasars.
Autor principal: 
Negrete, CA
Autor/es del IAA: 
Sulentic, Jack W.
DOI: 
10.1888/0004-637X/794/1/95
Revista: 
ASTROPHYSICAL JOURNAL
Fecha de publicación: 
2014/10/10
Volumen: 
794
Issue: 
1
Tipo de documento: 
Article
Palabras clave: 
galaxies: active; galaxies: high-redshift; quasars: emission lines; quasars: general
Número de artículo: 
95

Impact of lightning on the lower ionosphere of Saturn and possible generation of halos and sprites

Titulo: 
Impact of lightning on the lower ionosphere of Saturn and possible generation of halos and sprites
Autores: 
Dubrovin, D; Luque, A; Gordillo-Vazquez, FJ; Yair, Y; Parra-Rojas, FC; Ebert, U; Price, C
Resumen: 
We study the effect of lightning on the lower ionosphere of Saturn. A self-consistent one-dimensional model of the electric field and electron density is used to estimate the changes of the local electron and photon emissions. The chemical fingerprint and ion densities are determined using a detailed self-consistent kinetic model. Charge moment change, depth of lightning flashes and their duration are estimated based on the known constraints of saturnian lightning activity. We test two electron density profiles and find that the conservative estimation of lightning charge moment change 10(4) to 10(5) C km could lead to faint halos and possibly sprites if the base of the ionosphere is located at 1000 km above the 1 bar level; if the base of the ionosphere is located at 600 km then only the extreme scenario of a 10(6) C km charge moment change could induce considerable ionization, halos and possibly sprites. We found that H-3(+) ions are rapidly produced from the parent H-2(+) ions through the fast reaction H-2(+)+ H-2 --> H-3(+) + H, so that H-3(+) becomes the dominant ion in all the scenarios considered. The resulting light emissions, mostly in the blue and ultraviolet spectral regions, are below the detection threshold of Cassini. (C) 2014 Elsevier Inc. All rights reserved.
Autor principal: 
Dubrovin, D
Autor/es del IAA: 
Luque, A.; Gordillo-Vazquez, F. J.; Parra-Rojas, F. C.
DOI: 
10.1016/j.icarus.2014.06.025
Revista: 
ICARUS
Fecha de publicación: 
2014/10
Volumen: 
241
Páginas: 
313-328
Tipo de documento: 
Article
Palabras clave: 
Saturn; Lightning; Ionospheres

Vertical structure of stratospheric water vapour trends derived from merged satellite data

Titulo: 
Vertical structure of stratospheric water vapour trends derived from merged satellite data
Autores: 
Hegglin, MI; Plummer, DA; Shepherd, TG; Scinocca, JF; Anderson, J; Froidevaux, L; Funke, B; Hurst, D; Rozanov, A; Urban, J; von Clarmann, T; Walker, KA; Wang, HJ; Tegtmeier, S; Weigel, K
Resumen: 
Stratospheric water vapour is a powerful greenhouse gas. The longest available record from balloon observations over Boulder, Colorado, USA shows increases in stratospheric water vapour concentrations that cannot be fully explained by observed changes in the main drivers, tropical tropopause temperatures and methane. Satellite observations could help resolve the issue, but constructing a reliable long-term data record from individual short satellite records is challenging. Here we present an approach to merge satellite data sets with the help of a chemistry-climate model nudged to observed meteorology. We use the models' water vapour as a transfer function between data sets that overcomes issues arising from instrument drift and short overlap periods. In the lower stratosphere, our water vapour record extends back to 1988 and water vapour concentrations largely follow tropical tropopause temperatures. Lower and mid-stratospheric long-term trends are negative, and the trends from Boulder are shown not to be globally representative. In the upper stratosphere, our record extends back to 1986 and shows positive long-term trends. The altitudinal differences in the trends are explained by methane oxidation together with a strengthened lower-stratospheric and a weakened upper-stratospheric circulation inferred by this analysis. Our results call into question previous estimates of surface radiative forcing based on presumed global long-term increases in water vapour concentrations in the lower stratosphere.
Autor principal: 
Hegglin, MI
Autor/es del IAA: 
Funke, B.
DOI: 
10.1038/NGEO2236
Revista: 
NATURE GEOSCIENCE
Fecha de publicación: 
2014/10
Volumen: 
7
Issue: 
10
Páginas: 
768-776
Tipo de documento: 
Article

OMC/INTEGRAL photometric observations of pulsating components in eclipsing binaries and characterization of DY Aqr

Titulo: 
OMC/INTEGRAL photometric observations of pulsating components in eclipsing binaries and characterization of DY Aqr
Autores: 
Alfonso-Garzon, J; Montesinos, B; Moya, A; Mas-Hesse, JM; Martin-Ruiz, S
Resumen: 
We present the search for eclipsing binaries with a pulsating component in the first catalogue of optically variable sources observed by Optical Monitoring Camera (OMC)/INTEGRAL, which contains photometric data for more than 1000 eclipsing binaries. Five objects were found and a detailed analysis of one of them, DY Aqr, has been performed. Photometric and spectroscopic observations of DY Aqr were obtained to analyse the binary system and the pulsational characteristics of the primary component. By applying the binary modelling software PHOEBE to the OMC and ground-based photometric light curves, and to the radial velocity curve obtained using echelle high-resolution spectroscopy, the physical parameters of the system have been determined. Frequency analysis of the residual data has been performed using Fourier techniques to identify pulsational frequencies. We have built a grid of theoretical models to classify spectroscopically the primary component as an A7.5V star (plus or minus one spectral subtype). The best orbital fit was obtained for a semidetached system configuration. According to the binary modelling, the primary component has T-eff = 7625 +/- 125 K and log g = 4.1 +/- 0.1 and the secondary component has T-eff = 3800 +/- 200 K and log g = 3.3 +/- 0.1, although it is too faint to isolate its spectral features. From the analysis of the residuals, we have found a main pulsation frequency at 23.37 d(-1), which is typical of a delta Scuti star. In the O-C diagram, no evidence of orbital period changes over the last 8 yr has been found.
Autor principal: 
Alfonso-Garzon, J
Autor/es del IAA: 
Martin-Ruiz, S.
DOI: 
10.1093/mnras/stu1386
Revista: 
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Fecha de publicación: 
2014/10/01
Volumen: 
443
Issue: 
4
Páginas: 
3022-3032
Tipo de documento: 
Article
Palabras clave: 
techniques: photometric; techniques: radial velocities; techniques: spectroscopic; binaries: eclipsing; stars: variables: delta Scuti

First release of the IPHAS catalogue of new extended planetary nebulae

Titulo: 
First release of the IPHAS catalogue of new extended planetary nebulae
Autores: 
Sabin, L; Parker, QA; Corradi, RLM; Guzman-Ramirez, L; Morris, RAH; Zijlstra, AA; Bojicic, IS; Frew, DJ; Guerrero, M; Stupar, M; Barlow, MJ; Mora, FC; Drew, JE; Greimel, R; Groot, P; Irwin, JM; Irwin, MJ; Mampaso, A; Miszalski, B; Olguin, L; Phillipps, S; Garcia, MS; Viironen, K; Wright, NJ
Resumen: 
We present the first results of our search for new, extended planetary nebulae (PNe) based on careful, systematic, visual scrutiny of the imaging data from the Isaac Newton Telescope Photometric Ha Survey of the Northern Galactic plane (IPHAS). The newly uncovered PNe will help to improve the census of this important population of Galactic objects that serve as key windows into the late-stage evolution of low-to intermediate-mass stars. They will also facilitate study of the faint end of the ensemble Galactic PN luminosity function. The sensitivity and coverage of IPHAS allows PNe to be found in regions of greater extinction in the Galactic plane and/or those PNe in a more advanced evolutionary state and at larger distances compared to the general Galactic PN population. Using a set of newly revised optical diagnostic diagrams in combination with access to a powerful, new, multiwavelength imaging data base, we have identified 159 true, likely and possible PNe for this first catalogue release. The ability of IPHAS to unveil PNe at low Galactic latitudes and towards the Galactic Anticentre, compared to previous surveys, makes this survey an ideal tool to contribute to the improvement of our knowledge of the whole Galactic PN population.
Autor principal: 
Sabin, L
Autor/es del IAA: 
Guerrero, M.
DOI: 
10.1093/mnras/stu1404
Revista: 
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Fecha de publicación: 
2014/10/01
Volumen: 
443
Issue: 
4
Páginas: 
3388-3401
Tipo de documento: 
Article
Palabras clave: 
surveys; planetary nebulae: general

Formation and X-ray emission from hot bubbles in planetary nebulae - I. Hot bubble formation

Titulo: 
Formation and X-ray emission from hot bubbles in planetary nebulae - I. Hot bubble formation
Autores: 
Toala, JA; Arthur, SJ
Resumen: 
We carry out high-resolution two-dimensional radiation-hydrodynamic numerical simulations to study the formation and evolution of hot bubbles inside planetary nebulae. We take into account the evolution of the stellar parameters, wind velocity and mass-loss rate from the final thermal pulses during the asymptotic giant branch (AGB) through to the post-AGB stage for a range of initial stellarmasses. The instabilities that form at the interface between the hot bubble and the swept-up AGB wind shell lead to hydrodynamical interactions, photoevaporation flows and opacity variations. We explore the effects of hydrodynamical mixing combined with thermal conduction at this interface on the dynamics, photoionization, and emissivity of our models. We find that even models without thermal conduction mix significant amounts of mass into the hot bubble. When thermal conduction is not included, hot gas can leak through the gaps between clumps and filaments in the broken swept-up AGB shell and this depressurises the bubble. The inclusion of thermal conduction evaporates and heats material from the clumpy shell, which expands to seal the gaps, preventing a loss in bubble pressure. The dynamics of bubbles without conduction is dominated by the thermal pressure of the thick photoionized shell, while for bubbles with thermal conduction it is dominated by the hot, shocked wind.
Autor principal: 
Toala, JA
Autor/es del IAA: 
Toala, J. A.
DOI: 
10.1093/mnras/stu1360
Revista: 
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Fecha de publicación: 
2014/10/01
Volumen: 
443
Issue: 
4
Páginas: 
3486-3505
Tipo de documento: 
Article
Palabras clave: 
hydrodynamics; radiative transfer; planetary nebulae: general; X-rays: ISM

A dynamical model of the local cosmic expansion

Titulo: 
A dynamical model of the local cosmic expansion
Autores: 
Penarrubia, J; Ma, YZ; Walker, MG; McConnachie, A
Resumen: 
We combine the equations of motion that govern the dynamics of galaxies in the local volume with Bayesian techniques in order to fit orbits to published distances and velocities of galaxies within 3 Mpc. We find a Local Group (LG) mass 2.3 +/- 0.7 x 10(12)M(circle dot) that is consistent with the combined dynamical masses of M31 and the Milky Way, and a mass ratio 0.54(-0.17)(+0.23) that rules out models where our Galaxy is more massive than M31 with similar to 95 per cent confidence. The Milky Way's circular velocity at the solar radius is relatively high, 245 +/- 23 km s(-1), which helps to reconcile the mass derived from the local Hubble flow with the larger value suggested by the 'timing argument'. Adopting Planck's bounds on Omega(Lambda) yields a (local) Hubble constant H-0 = 67 +/- 5 kms(-1) Mpc(-1) which is consistent with the value found on cosmological scales. Restricted N-body experiments show that substructures tend to fall on to the LG along the Milky Way-M31 axis, where the quadrupole attraction is maximum. Tests against mock data indicate that neglecting this effect slightly overestimates the LG mass without biasing the rest of model parameters. We also show that both the time dependence of the LG potential and the cosmological constant have little impact on the observed local Hubble flow.
Autor principal: 
Penarrubia, J
Autor/es del IAA: 
Penarrubia, Jorge
DOI: 
10.1093/mnras/stu879
Revista: 
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Fecha de publicación: 
2014/09/21
Volumen: 
443
Issue: 
3
Páginas: 
2204-2222
Tipo de documento: 
Article
Palabras clave: 
Galaxy: fundamental parameters; Galaxy: kinematics and dynamics; Local Group; cosmological parameters; dark energy; dark matter

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