Oscillator strengths and transition probabilities of O II

Nahar, Sultana N.

doi:10.1016/j.adt.2010.07.002

Cited by 6 publications

(4 citation statements)

References 21 publications

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“…is that LS coupling is not assumed. More recently, non-LS oscillator strengths have become available through the Iron Project (Hummer et al 1993), and work done by the atomic-data group at Ohio State University (Nahar 2010). Other important sources of radiative data for Fe include Becker & Butler (1992, Nahar (1995).…”

Section: Discussionmentioning

confidence: 99%

Evidence for sub-Chandrasekhar-mass progenitors of Type Ia supernovae at the faint end of the width–luminosity relation

Blondin

Dessart

Hillier

et al. 2017

Monthly Notices of the Royal Astronomical Society

101

137

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The faster light-curve evolution of low-luminosity Type Ia supernovae (SNe Ia) suggests that they could result from the explosion of white dwarf (WD) progenitors below the Chandrasekhar mass (M Ch ). Here we present 1D non-local thermodynamic equilibrium time-dependent radiative transfer simulations of pure central detonations of carbon-oxygen WDs with a mass (M tot ) between 0.88 M ⊙ and 1.15 M ⊙ , and a 56 Ni yield between 0.08 M ⊙ and 0.84 M ⊙ . Their lower ejecta density compared to M Ch models results in a more rapid increase of the luminosity at early times and an enhanced γ-ray escape fraction past maximum light. Consequently, their bolometric light curves display shorter rise times and larger post-maximum decline rates. Moreover, the higher M( 56 Ni)/M tot ratio at a given 56 Ni mass enhances the temperature and ionization level in the spectrum-formation region for the less luminous models, giving rise to bluer colours at maximum light and a faster post-maximum evolution of the B − V colour. For sub-M Ch models fainter than M B ≈ −18.5 mag at peak, the greater bolometric decline and faster colour evolution lead to a larger B-band post-maximum decline rate, ∆M 15 (B). In particular, all of our previously-published M Ch models (standard and pulsational delayed detonations) are confined to ∆M 15 (B) < 1.4 mag, while the sub-M Ch models with M tot 1 M ⊙ extend beyond this limit to ∆M 15 (B) ≈ 1.65 mag for a peak M B ≈ −17 mag, in better agreement with the observed width-luminosity relation (WLR). Regardless of the precise ignition mechanism, these simulations suggest that fast-declining SNe Ia at the faint end of the WLR could result from the explosion of WDs whose mass is significantly below the Chandrasekhar limit.

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Section: Discussionmentioning

confidence: 99%

Evidence for sub-Chandrasekhar-mass progenitors of Type Ia supernovae at the faint end of the width–luminosity relation

Blondin

Dessart

Hillier

et al. 2017

Monthly Notices of the Royal Astronomical Society

101

137

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“…The ξ -factors for carbon were calculated with the use of photoionization cross section from [10] assuming the local thermodynamic equilibrium (LTE). The results are shown in Fig.…”

Section: Photon Absorptionmentioning

confidence: 99%

The effect of laser wavelength on heating of ablated carbon plume

2011

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The effect of laser wavelength on heating of the ablated carbon plume is studied. The plasma absorption coefficients are calculated in order to analyze the results and an experiment is conducted using the first, second, and third harmonic of a Nd:YAG laser. Plasma temperature and electron density in the early phase of expansion in vacuum are studied as a function of distance from the target. The calculations show that the ratio between absorption coefficients for 1064, 532, and 355 nm is approximately 9:2:1. The experimental results do not agree well with the theoretical predictions. Indeed, the plasma temperatures are highest in the case of 1064 nm but no clear differences between 532 nm and 355 nm have been found.

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“…Lines with the upper terms 3d 4 P and 3d 4 D also tend to be underestimated in our calculations, and the reason appears to be uncertainties in the transition probabilities. The A values for these terms calculated by Nahar () are significantly lower than those quoted in the NIST data base from Veres & Wise () and Bell et al (). The NIST values give a much better – albeit insufficient – match to observations with predicted intensities 0.09–0.4 times the measured value, far below the assumed observational uncertainty.…”

Section: Resultsmentioning

confidence: 61%

“…We used the transition probabilities of Nahar () supplemented with the intermediate‐coupling calculations for the 3d–4f array by Liu et al (), who found significant effects of LS coupling breakdown in 4f and some 3d terms. Terms with l ≥ 3 are better described in LK coupling (Wenåker ).…”

Section: Atomic Datamentioning

confidence: 99%

Excitation of emission lines by fluorescence and recombination in IC 418

Escalante

Morisset²,

Георгиев

2012

Monthly Notices of the Royal Astronomical Society

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We compare calculated intensities of lines of C ii, N i, N ii, O i and O ii with a published deep spectroscopic survey of IC 418. Our calculations use a self‐consistent nebular model and a synthetic spectrum of the central star atmosphere to take into account line excitation by continuum fluorescence and electron recombination. We found that the N ii spectrum of the s, p and most d states is excited by fluorescence due to the low‐excitation conditions of the nebula. Many C ii and O ii lines have significant amount of excitation by fluorescence. Recombination excites all the lines from the f and g states and most O ii lines. In the neutral‐ionized boundary, the N i quartet and O i triplet dipole‐allowed lines are excited by fluorescence, while the quintet O i lines are excited by recombination. Electron excitation produces the forbidden optical lines of O i, and continuum fluorescence enhances the N i forbidden line intensities. Lines excited by fluorescence of light below the Lyman limit thus suggest a new diagnostic to explore the inner boundary of the photodissociation region of the nebula.

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Oscillator strengths and transition probabilities of O II

Cited by 6 publications

References 21 publications

Evidence for sub-Chandrasekhar-mass progenitors of Type Ia supernovae at the faint end of the width–luminosity relation

Evidence for sub-Chandrasekhar-mass progenitors of Type Ia supernovae at the faint end of the width–luminosity relation

The effect of laser wavelength on heating of ablated carbon plume

Excitation of emission lines by fluorescence and recombination in IC 418

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