Influence of chemi-ionization and chemi-recombination  processes
on hydrogen line shapes in M dwarfs

Mihajlov, A. A.; Jevremović, D.; Hauschildt, P. H.; Dimitrijevic, M. S.; Ignjatovic, Lj.; Alard, F.

doi:10.1051/0004-6361:20077517

Cited by 26 publications

(72 citation statements)

References 12 publications

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“…Another important thing is that the presented results suggest that these processes, due to their influence on free electron density and excited state populations in the atmospheres of M red dwarfs, should also influence the atomic spectral line shapes (see e.g. Mihajlov et al (2007b)). …”

Section: Introductionmentioning

confidence: 77%

“…In previous works (Mihajlov et al 2003(Mihajlov et al , 2007b related to the photosphere of a M red dwarf with temperature near to 4000 K, it has been shown that on populations of hydrogenic Rydberg states in this photosphere as well as on its other characteristics, influence strongly just the chemi-ionization processes (1a) and (1b) with 4 ≤ n ≤ 8. It is clear that, already because of this, it is indispensable to take into account the changes of rate coefficients of these processes, which, in accordance with our results, are particularly large for n ≤ 6.…”

Section: Resultsmentioning

confidence: 99%

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Non-Elastic Processes in Atom Rydberg-Atom Collisions: Review of State of Art and Problems

et al. 2015

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In our previous research, it has been demonstrated that such inelastic processes in atom Rydbergatom collisions, as chemi-ionization and (n-n') mixing, should be considered together. Here we will review the present state of the art and the actual problems will be discussed. In this context, we will consider the influence of the (n-n')-mixing during a symmetric atom Rydberg-atom collision processes on the intensity of chemi-ionization process. It will be taken into account H(1s) + H*(n) collisional systems, where the principal quantum number n >> 1. It will be demonstrated that the inclusion of (nn') mixing in the calculation, influences significantly on the values of chemi-ionization rate coefficients, particularly in the lower part of the block of the Rydberg states. Different possible channels of the (n-n')-mixing influence on chemi-ionization rate coefficients will be demonstrated. The possibility of interpretation of the (n-n')-mixing influence will be considered on the basis of two existing methods for describing of the inelastic processes in symmetrical atom Rydberg-atom collisions.

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Section: Introductionmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Non-Elastic Processes in Atom Rydberg-Atom Collisions: Review of State of Art and Problems

et al. 2015

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“…This suggests that the examined processes, due to their influence on the excited state populations and the free electron density, should also influence the atomic spectral line shapes. Figure 5 (from [23]) shows the line profiles of H α , H δ , H Pa with and without the inclusion of (1a) and (1b) processes. Profiles are synthesized with PHOENIX code [8] with Stark broadening contribution.…”

Section: Astrophysical Targetsmentioning

confidence: 99%

The Collisional Atomic Processes of Rydberg Hydrogen and Helium Atoms: Astrophysical Relevance

et al. 2018

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Abstract:Elementary processes in astrophysical environments traditionally attract researchers' attention. We present the data needed for the inclusion of the specific atomic collisional processes in the investigation of the optical and kinetic properties of weakly ionized stellar atmosphere layers. The first type of processes are collisional ionisation (chemi-ionization) processes, and the second ones are excitation and de-excitation (i.e., (n − n )-mixing processes). We give the rate coefficients of the aforementioned processes for the conditions that exist in the solar photosphere, the atmosphere of DB white dwarfs, M-type red dwarfs, etc.

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“…It was demonstrated that the absorption processes (1) in the optical part of spectra should be considered in the Solar photosphere and the lower chromosphere together, since in this case their influences on the opacity are similar. In subsequent papers (Mihajlov et al 1993(Mihajlov et al , 1994a, the absorption processes (1) were investigated in more detail and their contributions to the solar opacity were determined by using standard Solar atmosphere models (Vernazza et al 1981;Maltby et al 1986). Then, these contributions were compared with the contributions of other relevant radiative processes, namely…”

Section: Introductionmentioning

confidence: 99%

“…In Mihajlov et al (1993Mihajlov et al ( , 1994a) the part of the optical region 365 nm ≤ λ ≤ 820 nm was taken into account. It was found that in this region the processes (1) give a contribution of 10-12% in comparison with processes (2).…”

Section: Introductionmentioning

confidence: 99%

The influence of H$\mathsf{_{2}^{+}}$- photo-dissociation and (H + H$\mathsf{^{+}}$)- radiative collisions on the solar atmosphere opacity in UV and VUV regions

Mihajlov¹,

Ignjatović²,

Sakan³

et al. 2007

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Aims. To estimate the total contribution of the absorption processes λ + H + 2 (X 2 Σ + g ) ⇒ H(1s) + H + and λ + H(1s) + H + ⇒ H + + H(1s) to the opacity of Solar atmosphere in UV and VUV region, and compare it with the contribution of other relevant radiative processes included in standard models. Methods. The strict quantum-mechanical method was used for the determination of the average cross-section for the photodissociation of the molecular ion H + 2 (X 2 Σ + g ); the previously developed quasi-static method was used for determination of the corresponding spectral coefficient which characterizes the absorption charge exchange in H(1s) + H + collisions. Results. Spectral absorption coefficients characterizing the considered processes were calculated for the solar photosphere and lower chromosphere, within the 90 nm ≤ λ ≤ 370 nm spectral range; the total contribution of the considered processes to the solar opacity was estimated and compared to relevant radiative processes included in standard Solar models. Conclusions. In comparison with other absorption processes included in standard Solar models, the contribution of the considered processes in the UV and VUV regions is so important that they have to be taken into account in modeling the Solar photosphere and the lower chromosphere.

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Influence of chemi-ionization and chemi-recombination processes on hydrogen line shapes in M dwarfs

Cited by 26 publications

References 12 publications

Non-Elastic Processes in Atom Rydberg-Atom Collisions: Review of State of Art and Problems

Non-Elastic Processes in Atom Rydberg-Atom Collisions: Review of State of Art and Problems

The Collisional Atomic Processes of Rydberg Hydrogen and Helium Atoms: Astrophysical Relevance

The influence of H$\mathsf{_{2}^{+}}$- photo-dissociation and (H + H$\mathsf{^{+}}$)- radiative collisions on the solar atmosphere opacity in UV and VUV regions

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