Chianti—an Atomic Database for Emission Lines. Xiii. Soft X-Ray Improvements and Other Changes

Landi, E.; Young, Peter R.; Dere, K. P.; Zanna, G. Del; Mason, H. E.

doi:10.1088/0004-637x/763/2/86

Cited by 449 publications

(416 citation statements)

References 56 publications

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“…Wittmann (1974) following Mihalas (1967). I found them in the github LTE repository of A. Asensio Ramos and extended them with data and routines in the SolarSoft CHIANTI package (e.g., Dere et al 1997;Landi et al 2013). My codes are available under IDL on my website.…”

Section: Equations and Implementationmentioning

confidence: 99%

Hαfeatures with hot onsets

Rutten

2016

A&A

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Ellerman bombs are transient brightenings of the wings of the Balmer lines that uniquely mark reconnection in the solar photosphere.They are also bright in strong Ca ii and ultraviolet lines and in ultraviolet continua, but they are not visible in the optical continuum and the Na i D and Mg i b lines. These discordant visibilities invalidate all published Ellerman bomb modeling. I argue that the assumption of Saha-Boltzmann lower-level populations is informative to estimate bomb-onset opacities for these diverse diagnostics, even and especially for Hα, and employ such estimates to gauge the visibilities of Ellerman bomb onsets in all of them. They constrain Ellerman bomb formation to temperatures 10 000−20 000 K and hydrogen densities around 10 15 cm −3 . Similar arguments likely hold for Hα visibility in other transient phenomena with hot and dense onsets.

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Section: Equations and Implementationmentioning

confidence: 99%

Hαfeatures with hot onsets

Rutten

2016

A&A

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“…The synthetic X-ray emission for each model at each time is computed using the extensively tested chianti database and software package (Version 7.1.3; Dere et al 1997Dere et al , 2009Landi et al 2013). The calculation performed by chianti includes the contributions due to lines and to free-free, freebound, and two-photon continua.…”

Section: Spectramentioning

confidence: 99%

“…The calculation performed by chianti includes the contributions due to lines and to free-free, freebound, and two-photon continua. We used the updated default ionization equilibrium ion fractions included in the latest version of chianti 4 (see Landi et al 2013, and references therein). The abundances used to compute the spectra are those defined for a standard PN composition in Cloudy version 13.0 (Ferland et al 2013), for consistency with Paper I.…”

Section: Spectramentioning

confidence: 99%

Formation and X-ray emission from hot bubbles in planetary nebulae – II. Hot bubble X-ray emission

Toalá¹,

Arthur²

2016

Mon. Not. R. Astron. Soc.

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We present a study of the X-ray emission from numerical simulations of hot bubbles in planetary nebulae (PNe). High-resolution, two-dimensional, radiation-hydrodynamical simulations of the formation and evolution of hot bubbles in PNe, with and without thermal conduction, are used to calculate the X-ray emission and study its timedependence and relationship to the changing stellar parameters. Instabilities in the wind-wind interaction zone produce clumps and filaments in the swept-up shell of nebular material. Turbulent mixing and thermal conduction at the corrugated interface can produce quantities of intermediate temperature and density gas between the hot, shocked wind bubble and the swept-up photoionized nebular material, which can emit in soft, diffuse X-rays. We use the chianti software to compute synthetic spectra for the models and calculate their luminosities. We find that models both with conduction and those without can produce the X-ray temperatures and luminosities that are in the ranges reported in observations, although the models including thermal conduction are an order of magnitude more luminous than those without. Our results show that at early times the diffuse X-ray emission should be dominated by the contribution from the hot, shocked stellar wind, whereas at later times the nebular gas will dominate the spectrum. We analyse the effect of sampling on the resultant spectra and conclude that a minimum of 200 counts is required to reliably reproduce the spectral shape. Likewise, heavily smoothed surface-brightness profiles obtained from low-count detections of PNe do not provide a reliable description of the spatial distribution of the X-ray emitting gas.

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“…For simplicity, we will quote the lifetimes derived from the calculations of Del Zanna (2009), which are tabulated in the CHIANTI atomic database (Landi et al 2013 In order to estimate the metastable fraction in the ion beam, we have used the procedure described by Lestinsky et al (2012) to evolve the level populations in time, based on the radiative transition rates. For the radiative transition data, we used the rates from the CHIANTI database, which includes 104 levels from the ground state up to an excitation energy of 132.66 eV (Del Zanna 2009;Landi et al 2013). The initial populations for this calculation were determined using a Boltzmann distribution with k B T e = 100 eV, where k B is the Boltzmann constant and T e is the electron temperature.…”

Section: Metastablesmentioning

confidence: 99%

Storage ring cross section measurements for electron impact ionization of Fe⁸⁺

Hahn

Becker

Bernhardt

et al. 2016

J. Phys. B: At. Mol. Opt. Phys.

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We have measured electron impact ionization (EII) for Fe 7+ from the ionization threshold up to 1200 eV. The measurements were performed using the TSR heavy ion storage ring. The ions were stored long enough prior to measurement to remove most metastables, resulting in a beam of 94% ground state ions. Comparing with the previously recommended atomic data, we find that the Arnaud & Raymond (1992) cross section is up to about 40% larger than our measurement, with the largest discrepancies below about 400 eV. The cross section of Dere (2007) agrees to within 10%, which is about the magnitude of the experimental uncertainties. The remaining discrepancies between measurement and the most recent theory are likely due to shortcomings in the theoretical treatment of the excitation-autoionization contribution.

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Chianti—an Atomic Database for Emission Lines. Xiii. Soft X-Ray Improvements and Other Changes

Cited by 449 publications

References 56 publications

Hαfeatures with hot onsets

Hαfeatures with hot onsets

Formation and X-ray emission from hot bubbles in planetary nebulae – II. Hot bubble X-ray emission

Storage ring cross section measurements for electron impact ionization of Fe⁸⁺

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Chianti—an Atomic Database for Emission Lines. Xiii. Soft X-Ray Improvements and Other Changes

Cited by 449 publications

References 56 publications

Hαfeatures with hot onsets

Hαfeatures with hot onsets

Formation and X-ray emission from hot bubbles in planetary nebulae – II. Hot bubble X-ray emission

Storage ring cross section measurements for electron impact ionization of Fe8+

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Resources

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Storage ring cross section measurements for electron impact ionization of Fe⁸⁺