The Acceleration of the Nebular Shells in Planetary Nebulae in the Milky Way Bulge

We present a systematic study of line widths in the [\ion{O}{3}]$\lambda$5007 and H$\alpha$ lines for a sample of 86 planetary nebulae in the Milky Way bulge based upon spectroscopy obtained at the \facility{Observatorio Astron\'omico Nacional in the Sierra San Pedro M\'artir (OAN-SPM)} using the Manchester Echelle Spectrograph. The planetary nebulae were selected with the intention of simulating samples of bright extragalactic planetary nebulae. We separate the planetary nebulae into two samples containing cooler and hotter central stars, defined by the absence or presence, respectively, of the \ion{He}{2} $\lambda$6560 line in the H$\alpha$ spectra. This division separates samples of younger and more evolved planetary nebulae. The sample of planetary nebulae with hotter central stars has systematically larger line widths, larger radii, lower electron densities, and lower H$\beta$ luminosities. The distributions of these parameters in the two samples all differ at significance levels exceeding 99%. These differences are all in agreement with the expectations from hydrodynamical models, but for the first time confirmed for a homogeneous and statistically significant sample of galactic planetary nebulae. We interpret these differences as evidence for the acceleration of the nebular shells during the early evolution of these intrinsically bright planetary nebulae. As is the case for planetary nebulae in the Magellanic Clouds, the acceleration of the nebular shells appears to be the direct result of the evolution of the central stars.Comment: accepted for publication in Astrophysical Journa

Analytical Solutions for Systems of Singular Partial Differential-Algebraic Equations

This paper proposes power series method (PSM) in order to find solutions for singular partial differential-algebraic equations (SPDAEs). We will solve three examples to show that PSM method can be used to search for analytical solutions of SPDAEs. What is more, we will see that, in some cases, Padé posttreatment, besides enlarging the domain of convergence, may be employed in order to get the exact solution from the truncated series solutions of PSM

Analytical Solutions for Systems of Singular Partial Differential-Algebraic Equations

This paper proposes power series method (PSM) in order to find solutions for singular partial differential-algebraic equations (SPDAEs). We will solve three examples to show that PSM method can be used to search for analytical solutions of SPDAEs. What is more, we will see that, in some cases, Padé posttreatment, besides enlarging the domain of convergence, may be employed in order to get the exact solution from the truncated series solutions of PSM

Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)

This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Localization and Broadband Follow-up of the Gravitational-wave Transient GW150914

A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams. </p

Localization and broadband follow-up of the gravitational-wave transient GW150914

A gravitational-wave transient was identified in data recorded by the Advanced LIGO detectors on 2015 September 14. The event candidate, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the gravitational wave data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network Circulars, giving an overview of the participating facilities, the gravitational wave sky localization coverage, the timeline and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the electromagnetic data and results of the electromagnetic follow-up campaign will be disseminated in the papers of the individual teams

Influencia de la niña y el niño sobre la precipitación de la ciudad de Villahermosa, Tabasco, México

The La Niña and El Niño effect was analized from the precipitation of Villahermosa city, in Tabasco, during the dry, moist and canicular periods. This effect was graphically and statistically analyzed from the average of ten days precipitation of the years of La Niña (cold phase), of El Niño (warm phase) and of the mixed years (which are ones influenced by the warm, the cold and normal phase, or sometimes by the three) with the normal years (years without event), between the period of 1950-2000. During La Niña¿s events the precipitation of the dry period decreased by 36 % with regard to the normal value, and in the moist and canicular periods it increased by 9 % and 57 %, respectively. When El Niño occurred the precipitation of the dry period decreased by 27 %, while for the moist and canicular periods it increased 0.5 % and 12 %, respectively. In the mixed years the precipitation decreased in all periods: in the dry period by 30 %, in the moist perid by 18 % and in the canicular period by 6 %. Afterwards, the Fisher's variances comparison test was applied, to estimate whether the variation of ten days precipitation during the event was aleatory or whether it originated from an ocean-atmosphere phenomenon. The variation of the precipitation of the dry and canicular periods during La Niña was significant (p = 0.001) and although it was not significant for the moist period (p = 0.05). In El Niño's case it was significant (p = 0.01) for the dry and canicular periods, but it was not significant for the moist period (p = 0.05). For the mixed years the decrease of the precipitation of the dry and moist periods was significant ( p = 0.001) and it was also significant for the canicular period (p = 0.05). The statistical analysis showed that the El Niño and La Niña events, affected the precipitation of the dry and canicular periods of Villahermosa city and for the mixed years it affects all periods.El efecto de La Niña y El Niño se estudió sobre la precipitación de la ciudad de Villahermosa, Tabasco, durante los períodos seco, húmedo y canicular. Este efecto se analizó gráficamente y estadísticamente mediante la precipitación promedio por decena, de los años de La Niña (fase fría), El Niño (fase caliente) y años mixtos (estos años tienen influencia de fase caliente, fría y fase normal o de las tres) con los años normales (años sin evento) del período 1950-2000. Durante los eventos de La Niña la precipitación del período seco disminuyó 36 % con respecto al valor normal, y en el período húmedo y canicular aumentó 9 % y 57 %, respectivamente. Cuando se presentó El Niño la precipitación del período seco disminuyó 27 %, mientras que para el período húmedo y canicular aumentó 0.5 % y 12 %, respectivamente. En los años mixtos la precipitación disminuyó en todos los períodos: el seco 30 %, el húmedo 18 % y el canicular 6 %. Posteriormente, la prueba de comparación de varianzas de Fisher se aplicó para estimar sí la variación de la precipitación por decena, durante el evento era aleatoria o se debía a un fenómeno océano-atmósfera. La variación de la precipitación de los períodos seco y canicular durante La Niña fue significativa (p = 0.001), y no resultó significativa para el período húmedo (p = 0.05 ). En el caso de El Niño resultó significativa (p = 0.01) para los períodos seco y canicular y no significativa (p = 0.05) para el período húmedo. Para años mixtos la disminución de la precipitación de los períodos seco (p=0.001), húmedo (p = 0.001), y canicular (p = 0.05) fueron significativas. El análisis estadístico indicó que los eventos El Niño y La Niña afectaron la precipitación del período seco y canicular de la ciudad de Villahermosa y para años mixtos el efecto es en todos los período

Modified nonlinearities distribution Homotopy Perturbation method as a tool to find power series solutions to ordinary differential equations

En este artículo, el método modificado de perturbación homotópica con distribución de no linealidades (MNDHPM) es utilizado para encontrar soluciones en series de potencias de ecuaciones diferenciales ordinarias, tanto lineales como no lineales. Se verá que el método es particularmente relevante en algunos casos de ecuaciones con coeficientes no polinomiales e inhomogéneas con términos no homogéneos no polinomiales