8 research outputs found
Herschel PACS and SPIRE observations of blazar PKS 1510-089: a case for two blazar zones
We present the results of observations of blazar PKS 1510-089 with the
Herschel Space Observatory PACS and SPIRE instruments, together with
multiwavelength data from Fermi/LAT, Swift, SMARTS and SMA. The source was
found in a quiet state, and its far-infrared spectrum is consistent with a
power-law with a spectral index of alpha ~ 0.7. Our Herschel observations were
preceded by two 'orphan' gamma-ray flares. The near-infrared data reveal the
high-energy cut-off in the main synchrotron component, which cannot be
associated with the main gamma-ray component in a one-zone leptonic model. This
is because in such a model the luminosity ratio of the External-Compton and
synchrotron components is tightly related to the frequency ratio of these
components, and in this particular case an unrealistically high energy density
of the external radiation would be implied. Therefore, we consider a
well-constrained two-zone blazar model to interpret the entire dataset. In this
framework, the observed infrared emission is associated with the synchrotron
component produced in the hot-dust region at the supra-pc scale, while the
gamma-ray emission is associated with the External-Compton component produced
in the broad-line region at the sub-pc scale. In addition, the optical/UV
emission is associated with the accretion disk thermal emission, with the
accretion disk corona likely contributing to the X-ray emission.Comment: 13 pages, 8 figures, 7 tables; accepted for publication in the
Astrophysical Journa
A Herschel study of Planetary Nebulae
We present Herschel PACS and SPIRE images of the dust shells around the
planetary nebulae NGC 650, NGC 6853, and NGC 6720, as well as images showing
the dust temperature in their shells. The latter shows a rich structure, which
indicates that internal extinction in the UV is important despite the highly
evolved status of the nebulae.Comment: 2 pages, 1 figure, 2012, proceedings IAU Symposium 283 Planetary
Nebulae: An Eye to the Futur
The Herschel Planetary Nebula Survey (HerPlaNS) - a comprehensive dusty photoionization model of NGC6781
We perform a comprehensive analysis of the planetary nebula (PN) NGC6781 to
investigate the physical conditions of each of its ionized, atomic, and
molecular gas and dust components and the object's evolution, based on
panchromatic observational data ranging from UV to radio. Empirical nebular
elemental abundances, compared with theoretical predictions via nucleosynthesis
models of asymptotic giant branch (AGB) stars, indicate that the progenitor is
a solar-metallicity, 2.25-3.0 Msun initial-mass star. We derive the best-fit
distance of 0.46 kpc by fitting the stellar luminosity (as a function of the
distance and effective temperature of the central star) with the adopted
post-AGB evolutionary tracks. Our excitation energy diagram analysis indicate
high excitation temperatures in the photodissociation region (PDR) beyond the
ionized part of the nebula, suggesting extra heating by shock interactions
between the slow AGB wind and the fast PN wind. Through iterative fitting using
the Cloudy code with empirically-derived constraints, we find the best-fit
dusty photoionization model of the object that would inclusively reproduce all
of the adopted panchromatic observational data. The estimated total gas mass
(0.41 Msun) corresponds to the mass ejected during the last AGB thermal pulse
event predicted for a 2.5 Msun initial-mass star. A significant fraction of the
total mass (about 70 percent) is found to exist in the PDR, demonstrating the
critical importance of the PDR in PNe that are generally recognized as the
hallmark of ionized/H+ regions.Comment: 34 pages, 13 Figures and 16 Tables, accepted for publication in the
Astrophysical Journal Supplement Serie
Herschel Planetary Nebula Survey (HerPlaNS): Hydrogen Recombination Laser Lines in Mz 3
The bipolar nebula Menzel 3 (Mz 3) was observed as part of the
\textit{Herschel} Planetary Nebula Survey (\textit{HerPlaNS}), which used the
PACS and SPIRE instruments aboard the \textit{Herschel Space Observatory} to
study a sample of planetary nebulae (PNe). In this paper, one of the series
describing \textit{HerPlaNS} results, we report the detection of H I
recombination lines (HRLs) in the spectrum of Mz 3. Inspection of the spectrum
reveals the presence of 12 HRLs in the 55 to 680 m range covered by the
PACS and SPIRE instruments (H11 to H21 and H14). The
presence of HRLs in this range is unusual for PNe and has not been reported in
Mz 3 before. Our analysis indicates that the HRLs we observed are enhanced by
laser effect occurring in the core of Mz 3. Our arguments for this are: (i) the
available Mz 3 optical to submillimetre HRL line intensity ratios are
not well reproduced by the spontaneous emission of optically thin ionized gas,
as would be typical for nebular gas in PNe; (ii) the compact core of Mz 3 is
responsible for a large fraction of the Herschel HRLs emission; (iii) the line
intensity ratios for Mz 3 are very similar to those in the core emission of the
well known star MWC 349A, where laser effect is responsible for the enhancement
of HRLs in the Herschel wavelength range; (iv) the physical characteristics
relevant to cause laser effect in the core of MWC 349A are very similar to
those in the core of Mz 3.Comment: Published in MNRAS. ESA Portal Story. 13 Pages, 7 figure
EOSC-Life Report on the work of the initial demonstrators
Leitner F, Carazo JM, Bischof J, et al. EOSC-Life Report on the work of the initial demonstrators.This deliverable 3.2 is a report on the demonstrator projects, the eight scientific and technical pilot projects that were selected to provide concrete scientific use-cases and guide and structure the work done in EOSC-Life to build an open digital and collaborative space for biological and medical research.
We report in this deliverable
the process of integration of the demonstrators within EOSC-Life,
the achievement of the demonstrators who developed and made available to the scientific community several valuable resources (databases, workflows, web platform...),
the actions undertaken within EOSC-Life to disseminate the demonstrator achievement and finally
the results of the demonstrator survey to learn from the demonstrator experience and improve the integration of the new pilot project within EOSC-Life.
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âBe sustainableâ: EOSCâLife recommendations for implementation of FAIR principles in life science data handling
The main goals and challenges for the life science communities in the Open Science framework are to increase reuse and sustainability of data resources, software tools, and workflows, especially in largeâscale dataâdriven research and computational analyses. Here, we present key findings, procedures, effective measures and recommendations for generating and establishing sustainable life science resources based on the collaborative, crossâdisciplinary work done within the EOSCâLife (European Open Science Cloud for Life Sciences) consortium. Bringing together 13 European life science research infrastructures, it has laid the foundation for an open, digital space to support biological and medical research. Using lessons learned from 27 selected projects, we describe the organisational, technical, financial and legal/ethical challenges that represent the main barriers to sustainability in the life sciences. We show how EOSCâLife provides a model for sustainable data management according to FAIR (findability, accessibility, interoperability, and reusability) principles, including solutions for sensitiveâ and industryârelated resources, by means of crossâdisciplinary training and best practices sharing. Finally, we illustrate how data harmonisation and collaborative work facilitate interoperability of tools, data, solutions and lead to a better understanding of concepts, semantics and functionalities in the life sciences