ABSTRACT
Considered here is the interrelation between five diffuse interstellar bands (DIBs), λλ 5545, 6113, 6196, 6445 and 6614 Å. Two DIBs (λλ 6196 and 6614 Å) are already known as being well ...correlated with each other; their relation with three other weaker bands is investigated for the first time. To accomplish this task, high-resolution spectra (λ/δλ ≈100 000) with high signal-to-noise ratios (S/N) of 54 hot O–B stars with reddening 0.12–1.45 mag were used. Analysis of measured equivalent widths has allowed us to establish linear dependences and evaluate linear correlation coefficients as high as 0.968–0.988 between the intensities of these five DIBs. Such a degree of correlation may indicate their common origin. Several spacings in wavenumbers found between these DIBs correspond to the energies of vibrational transitions in some polycyclic aromatic hydrocarbons resulting in IR emissions at λλ 16.4, 11.3, 7.7, 6.2 and 3.3 μm.
ABSTRACT
The goal of this study is tracking of possible changes in the spectrum of the interstellar cloud seen along the sightline towards a runaway star AE Aur. The study considers variations in the ...radial velocities of the interstellar molecules and atoms, dwelling in the cloud, for the period ≈17 yr. The most recent results of 6 yr monitoring of equivalent widths variability for the CH and CH+ absorption lines are also presented. The study was done using the CH B-X(0,0) 3886 Å, A-X (0,0) 4300 Å and the CH+ A-X (1-0) 3958 Å, A-X (0,0) 4232 Å lines as well as the interstellar potassium K i 7699 Å line. Moreover, a short discussion concerning the distance to the star is included. The present study is a continuation of our previous works and works of other researchers dedicated to the problem of small-scale structure in diffuse interstellar clouds. High resolution optical spectra from different spectrographs have been used in this work. The results of the study do not demonstrate significant changes in the radial velocities of the spectral features mentioned. The intensities of the CH and CH+ lines show slight tendency to vary at 1–3 per cent level.
This paper presents an atlas of diffuse interstellar bands together with tables with measurements of their parameters: central wavelengths, full widths at half-maximum and equivalent widths. For this ...goal the spectra of ten reddened, early-type stars have been selected. The spectra are of high resolution, ∼100 000, and reasonable signal-to-noise ratio, S/N > 300; they cover a wide spectral range 3500-10 000 Å and show a lack of evident Doppler splitting in the interstellar K i line. The measurement technique has allowed a homogeneous set of data to be achieved. As a result, the identity of 336 DIBs from previous surveys has been confirmed and 21 new bands have been found. The spectral plots and the tables are available online.
The thermodynamic description of the entire ternary Al-Nb-Ti system is obtained by CALPHAD modelling of the Gibbs energy of all individual phases, taking into account experimental data on phase ...equilibria and thermodynamic properties published and complemented by own experiments. The description includes a re-evaluation of the constituent binary Al-Nb system. Selected equilibrium calculations were performed with the Thermo-Calc software using the proposed description. They are shown to well reproduce experimental data on both, phase equilibria and thermodynamic properties in the entire Al-Nb-Ti system.
Charge asymmetry in decays B →DD¯K Bondar, A. E.; Milstein, A. I.
The journal of high energy physics,
12/2020, Volume:
2020, Issue:
12
Journal Article
Peer reviewed
Open access
A
bstract
We discusses the charge asymmetry in
B →
D
D
¯
K
decays with an invariant mass of the
D
D
¯
pair near the Ψ(3770) resonance. Unlike Ψ(3770) decays in
e
+
e
−
annihilation, in
B
+
decays the ...probability of
D
0
D
¯
0
production is almost three times higher than
D
+
D
−
. In
B
0
decays, the ratio of these probabilities will be opposite. The effect is explained by the fact that, in
B
-meson decays, the
D
D
¯
pair is produced in a superposition of isoscalar and isovector states, and only in combination with
K
-mesons the total state has 1
/
2 isospin. We present a simple model in which the interference of the nonresonant isovector amplitude with the resonant isoscalar amplitude explains the experimental data.
A method for measuring cross sections at
colliders for the case where the center-of-mass frame of colliding particles moves in the laboratory frame is proposed. Within this method, the energy ...dependence of the cross section is extracted from the angular distribution of interaction products. The method applied to the
process is found to be sensitive. This method provides the possibility of studying the fine structure of the cross section near the threshold at scales much less than the energy spread of the beams used. Similar measurements may be implemented in experiments at the Super Charm-Tau Factory.
The thermodynamic description of the binary system Al-Ti is obtained by modelling the Gibbs energy of all individual phases using the CALPHAD approach. The model parameters have been evaluated by ...means of the computer optimization module PARROT, available within Thermo-Calc, taking into account recent experimental data and critically assessed information on phase equilibria and thermodynamic properties. The calculations are in close agreement with the experimental data on both phase equilibria and thermodynamics in the entire Al-Ti system.
A
bstract
A method for measuring the average longitudinal polarization of the electron beam at an electron-positron collider operating near the
J
/
ψ
resonance is proposed. The method utilizes the ...differential cross-section of
J
/
ψ
→
Λ
→
p
π
−
Λ
→
p
¯
π
+
decay. It can be used to measure the average longitudinal polarization of electrons with the statistical precision better than 10
−3
at a Super Charm-Tau factory operating at the luminosity of 10
35
cm
−2
s
−1
. The method is discussed in the context of the weak mixing angle measurement in the same experiment.
The laboratory gas-phase spectrum recently published by Campbell et al. has reinvigorated attempts to confirm the presence of the C... cation in the interstellar medium, through an analysis of the ...spectra of hot, reddened stars. This search is hindered by at least two issues that need to be addressed: (i) the wavelength range of interest is severely polluted by strong water-vapour lines coming from the Earth's atmosphere; (ii) one of the major bands attributed to C... , at 9633 A, is blended with the stellar Mg ii line, which is susceptible to non-local thermodynamic equilibrium effects in hot stellar atmospheres. Both these issues are carefully considered here for the first time, based on high-resolution and high signal-to-noise ratio echelle spectra for 19 lines of sight. The result is that the presence of C... in interstellar clouds is brought into question. (ProQuest: ... denotes formulae/symbols omitted.)
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