ChemInform Abstract: ORGANOBORON MONOSACCHARIDES. 7. PURE D‐GULOSE FROM D‐GULONO‐1,4‐LACTONE

Koêster, R.; Idelmann, Peter; Dahlhoff, W. V.

doi:10.1002/chin.198042272

Cited by 11 publications

(30 citation statements)

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“…(4) with 3 ≤ n ≤ 8, on the basis of DB white dwarf atmosphere models from Koester (1980) for log g = 8 and T eff = 12 000 K and 14 000 K, as functions of log τ, where τ is the Rosseland optical depth. and its behavior in the atmospheres of the considered DB white dwarfs (which is very important for the studied processes) is presented in Fig.…”

Section: Fig 2 Behavior Of Quantities F (+)mentioning

confidence: 99%

“…and its behavior in the atmospheres of the considered DB white dwarfs (which is very important for the studied processes) is presented in Fig. 1. Figure 2 illustrates the behavior of the quantity F (+) n with 3 ≤ n ≤ 8 in the DB white dwarf atmospheres described by the models presented in Koester (1980), for log g = 8 and T eff = 12 000 K and 14 000 K. All results were obtained using the data from Koester (1980), and these quantities are presented as functions of log τ, where τ is the Rosseland optical depth. Figure 2 unambiguously shows that for DB white dwarf atmospheres with T eff 14 000 K, the excitation processes (1) in the lower part of the Rydberg block (3 ≤ n ≤ 8) must be taken into account as a new important factor that influences the helium Rydberg-state populations.…”

Section: Fig 2 Behavior Of Quantities F (+)mentioning

confidence: 99%

“…However, since the influence of strong electromagnetic emission is the same in helium-rich atmospheres as in the Sun, the distribution shape of the helium excited-atom population probably deviates considerably from the Boltzmann distribution. Taking this into account and because the data on the relative efficiencies of atom-Rydberg atom processes and the relevant concurrent processes would be useful for future non-LTE stellar-atmosphere models, the chemi-ionization processes in He * (n) + He collisions were studied in Mihajlov et al (2003) in the context of DB white dwarf atmospheres, within the models proposed by Koester (1980). In the current A&A 552, A33 (2013) study, for the same reason and using the same models, the efficiencies of the excitation processes…”

Section: Introductionmentioning

confidence: 99%

“…The necessary calculations were performed using the models in Koester (1980) for DB white dwarf atmospheres with log g = 8 and T eff = 12 000 K and T eff = 14 000 K.…”

Section: Introductionmentioning

confidence: 99%

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Excitation and deexcitation processes in atom-Rydberg atom collisions in helium-rich white dwarf atmospheres

Srećković

Mihajlov

Ignjatović

et al. 2013

A&A

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We aim to show the importance of non-elastic excitation and deexcitation processes in He * (n) + He(1s 2 ) collisions with the principal quantum number n ≥ 3 for helium-rich white dwarf atmospheres. We compare the efficiencies of these processes with those of the known non-elastic electron-He * (n) atom processes in the atmospheres of some DB white dwarfs. We show that in significant parts of the considered atmospheres, which contain weakly ionized layers (the ionization degree 10 −3 ), the influence of the studied atomRydberg atom processes on excited helium atom populations is dominant or at least comparable to the influence of the concurrent electron-He * (n)-atom processes.

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Section: Fig 2 Behavior Of Quantities F (+)mentioning

confidence: 99%

Section: Fig 2 Behavior Of Quantities F (+)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The necessary calculations were performed using the models in Koester (1980) for DB white dwarf atmospheres with log g = 8 and T eff = 12 000 K and T eff = 14 000 K.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Excitation and deexcitation processes in atom-Rydberg atom collisions in helium-rich white dwarf atmospheres

Srećković

Mihajlov

Ignjatović

et al. 2013

A&A

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“…We therefore classify it as a DB WD. The equivalent width of the He i 4471 Å absorption line is 13.4 Å, suggesting T eff ∼ 15,000 K for log g = 8.0 (Koester 1980). A detailed analysis of this object and its probability of cluster membership will be presented in a future paper.…”

Section: Notes On Individual Objectsmentioning

confidence: 99%

The White Dwarf Population in NGC 1039 (M34) and the White Dwarf Initial-Final Mass Relation

Rubin

Williams

Bolte

et al. 2008

The Astronomical Journal

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We present the first detailed photometric and spectroscopic study of the white dwarfs (WDs) in the field of the ∼225 Myr old (log τ cl = 8.35) open cluster NGC 1039 (M34) as part of the ongoing Lick-Arizona White Dwarf Survey. Using wide-field UBV imaging, we photometrically select 44 WD candidates in this field. We spectroscopically identify 19 of these objects as WDs; 17 are hydrogen-atmosphere DA WDs, one is a heliumatmosphere DB WD, and one is a cool DC WD that exhibits no detectable absorption lines. We find an effective temperature (T eff ) and surface gravity (log g) for each DA WD by fitting Balmer-line profiles from model atmospheres to the observed spectra. WD evolutionary models are then invoked to derive masses and cooling times for each DA WD. Of the 17 DAs, five are at the approximate distance modulus of the cluster. Another WD with a distance modulus 0.45 mag brighter than that of the cluster could be a double-degenerate binary cluster member, but is more likely to be a field WD. We place the five single cluster member WDs in the empirical initial-final mass relation and find that three of them lie very close to the previously derived linear relation; two have WD masses significantly below the relation. These outliers may have experienced some sort of enhanced mass loss or binary evolution; however, it is quite possible that these WDs are simply interlopers from the field WD population. Eight of the 17 DA WDs show significant Ca ii K absorption; comparison of the absorption strength with the WD distances suggests that the absorption is interstellar, though this cannot be confirmed with the current data.

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The self-consistent determination of HF electroconductivity of strongly coupled plasmas

Srećković¹,

Adamyan

Ignjatović³

et al. 2010

Physics Letters A

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Here is presented the calculation of the dynamic electrical conductivity of fully ionized, strongly coupled plasmas as a function of the external electric field frequency ω. The calculations are based on the the formula for the energy-dependent collision frequency which is determined by means of the Green function theory methods, as a sum over the Matsubara frequencies. The domain of extremely high electron density: 10 21 ≤ n e ≤ 10 24 cm −3 , and for the temperature varying from 10 kK to 1.000 kK was examined. The real and imaginary parts of the conductivity for every electron density are presented in the generalized Drude-like form as a two-parameter function of the frequency ω in the region 0 < ω < 0.5ω p , where ω p is the plasma frequency. A good agreement between the obtained results and the existing theoretical and computing simulation data is shown.

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ChemInform Abstract: ORGANOBORON MONOSACCHARIDES. 7. PURE D‐GULOSE FROM D‐GULONO‐1,4‐LACTONE

Cited by 11 publications

References 1 publication

Excitation and deexcitation processes in atom-Rydberg atom collisions in helium-rich white dwarf atmospheres

Excitation and deexcitation processes in atom-Rydberg atom collisions in helium-rich white dwarf atmospheres

The White Dwarf Population in NGC 1039 (M34) and the White Dwarf Initial-Final Mass Relation

The self-consistent determination of HF electroconductivity of strongly coupled plasmas

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