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1
Content available remote Looking for the Weak Members of the C60+ Family in the Interstellar Medium
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Galazutdinov G. A. , Krełowski J.
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2017
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tom Vol. 67, No. 2
159--169
EN
We demonstrate, using the high resolution spectra from the ESPADONS spectrograph, fed with the 3.6 m CFH telescope, that the strength ratios of the strong-to-weak spectral features, attributed to C60+, are variable. We found that in the range of expected 9366 Å C60+ feature there are two diffuse bands centered at 9362.0±0.1 Å and 9365.3±0.1 Å with variable intensity ratio. We confidently confirm the lack of 9428 Å feature which, in the laboratory spectra of C60+, is stronger than 9366 Å. The weakest laboratory feature, near 9348.4 Å, remains below the level of detection in all spectra. The intensity ratio 9577/9365 is variable. These facts contradict the possibility of their common origin and so - the identification of some interstellar spectral features as being carried by the cation of the "soccer ball". We also refined the rest wavelength position of the strongest diffuse band in this range: it is 9576.8±0.1 Å.
2
Content available remote On the Relations between Carriers of Interstellar Absorptions
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Krełowski J. , Strobel A.
Acta Astronomica
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2024
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tom Vol. 74, No. 1
69--76
EN
The paper demonstrates that intensities of the unidentified diffuse interstellar bands, likely carried by some complex molecules, are not correlated with the amount of reddening (color excess). Apparently the above mentioned molecules and dust grains causing the reddening do not occupy the same places in the interstellar medium extended along the sight-lines to the relatively nearby and young objects of the Eta Car stellar aggregate
3
Content available remote Gray Extinction in the Orion Trapezium
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Krełowski J. , Galazutdinov G. A. , Strobel A. , Mulas G.
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tom Vol. 66, No. 4
469--480
EN
We estimated distances to several Orion Trapezium stars using our CaII-method and confirm the distance recommended by Menten et al. However, we found that in the case of HD 37020 both individual distances (based on the trigonometric VLBI parallax and/or CaII-method) differ from the spectrophotometric distance by a factor of 2.5. We interpret this fact as a result of presence of gray (neutral) extinction of about 1.8 mag in front of this star. The correctness of the applied spectral type/ luminosity class, Sp/L, (based on new original spectra from HARPS-N) and measurements of color indices is discussed
4
Content available remote On the Relation between Interstellar Spectral Features and Reddening
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Krełowski J. , Galazutdinov G. , Godunova V. , Bondar A.
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2019
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tom Vol. 69, No. 2
159--175
EN
It is well known that interstellar spectral features correlate with color excess E(B-V). This suggests that measuring intensities of these features allows one to estimate reddening of stars. The aim of this paper is to check how tight intensities of interstellar diffuse bands (DIBs) are related to the amount of extinction, measured using E(B-V). We have measured equivalent widths of the strongest DIBs (centered at λλ 5780.6 Å, 5797.0 Å, 6196.0 Å, 6379.3 Å, 6613.5 Å, and 8620 Å), as well as of CH (near 4300.3 Å) and CH+ (near 4232.5 Å) in high resolution, high S/N ratio échelle spectra from several spectrographs. The equivalent widths of the 8620 DIB in noisy spectra were measured using a template which was constructed using the high quality spectrum of BD+40 4220. DIB relations with the color excess in the range 0.1-2.0 mag were examined. Our analysis demonstrates that all the above mentioned interstellar spectral features (except for, perhaps, 6379 DIB) do correlate with E(B-V) relatively tightly (with the Pearson's correlation coefficient of 0.8+). Moreover, the observed scatter is apparently not caused by measurement errors but of physical origin. We present several examples where the strength ratios of a DIB/molecule to E(B-V) are different than the average.
5
Content available remote Diffuse Interstellar Bands and Temperatures in the Interstellar Clouds
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Gnaciński P. , Weselak T. , Krełowski J.
Acta Astronomica
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2016
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tom Vol. 66, No. 1
121--130
EN
The diffuse interstellar bands (DIBs) observed in the optical and infrared spectrum of interstellar clouds remain the oldest unsolved problem in spectroscopy. We have analyzed correlations between normalized DIBs equivalent widths (EW's) and temperatures of interstellar H2 and CN molecules. The λ6284 Å DIB is well correlated with T temperature of H2. The correlation may be caused by DIB profile broadening or more effective production of DIB carrier at higher temperatures. The DIBs: λ4964 Å, λ5797 Å and λ6614 Å are anti-correlated with T temperature of H2. The anti-correlation may be attributed to destruction of DIBs carriers in high-UV radiation fields.
6
Content available remote Consistent System of Oscillator Strengths of A2Δ-X2Π (0,0) and B2Σ--X2Π (0,0) Bands of CH Molecule
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Weselak T. , Galazutdinov G. A. , Gnaciński P. , Krełowski J.
Acta Astronomica
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2014
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tom Vol. 64, No. 3
277--292
EN
Detailed analysis of intensity ratios of unsaturated methylidyne (CH) A-X and B-X bands suggests consistency of the recently published oscillator strengths of A2Δ-X2Π (0,0) - 4300 Å and B2Σ- - X2Π (0,0) - (3878 Å, 3886 Å and 3890 Å) bands (i.e. 506, 107, 320 and 213×10-5 respectively). This result is based on extremely high S/N ratio spectra of 45 stars, acquired with three high-resolution spectrographs, situated in Chile: ESO La Silla (HARPS), ESO Paranal (UVES) and Las Campanas (MIKE) and MAESTRO instrument situated in Northern Caucasus (Russia). The calculated methylidyne column densities, obtained using the consistent system of the oscillator strengths toward the observed targets, are given as well. We verify oscillator strengths of the CH+ A-X (0,0) and (0,1) bands at 4232 Å and 3957 Å equal to 545 and 342×10-5 respectively. We also confirm the lack of correlation between abundances of neutral CH and CH+ which demonstrates that they are originated in different environments.
7
Content available remote Constant Intensities of Diffuse Interstellar Bands in the Spectrum of AE Aur
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Krełowski J. , Galazutdinov G. A. , Bondar A. , Byeong-Cheol L.
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tom Vol. 67, No. 1
71--80
EN
Using spectra of the star AE Aur (HD 34078), covering the period 1997-2016, we prove that all strong diffuse interstellar bands are of the same intensity during the whole period of observations (inside 3-5% of the intensity). This is in sharp contrast to the behavior of both CH and CH+ features which, during the last six years, declined sharply by 13% and 28% respectively. Diffuse bands seem to behave more or less as interstellar atomic lines. We checked also the behavior of CaII lines which should be of constant intensities as the carrier fills the space evenly. Our observations confirm this and allow us to re-estimate the distance to HD 34078.
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Content available remote Spectrophotometric Distances - Problem of Interstellar Extinction
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Krełowski J. , Galazutdinov G. A. , Strobel A. , Bondar A.
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2017
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tom Vol. 67, No. 3
281--296
EN
Distances to 112 hot reddened stars in the thin Galactic disk have been estimated with different methods and, their accuracies have been compared. Also, we have applied the CaII-method to test its relation to trigonometric parallax and the spectrophotometric one. Some interstellar clouds apparently contain especially large size dust grains which cause interstellar gray (neutral) extinction. The latter does not correlate with the typical color extinction and may falsify spectrophotometric distance estimates. We conclude that CaII and TiII based method provides in many cases the most correct and reliable distance estimates to hot, bright, distant stars in the thin disk of the Milky Way - more accurate than obtained with the spectrophotometric method.
9
Content available remote Carriers of 4964 and 6196 Diffuse Interstellar Bands and Environments Dominated by either CH or CH+ Molecules
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Weselak T. , Galazutdinov G. A. , Sergeev O. , Godunova V. , Kołos R. , Krełowski J.
Acta Astronomica
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2014
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tom Vol. 64, No. 4
371--382
EN
The analysis of radial velocities of interstellar spectral features: CH, CH+ as well as 4964 and 6196 diffuse interstellar bands, seen in spectra of HD 151932 and HD 152233, suggests that carrier of the former is spatially correlated with CH while that of the latter - with CH+. A further analysis, done in this paper and based on the sample of 106 reddened OB stars, partly confirms this suggestion, showing that the CH column density correlates indeed much better with the equivalent width of the 4964 DIB than with that of the 6196 DIB. However, the strengths of the 6196 DIB correlate only marginally better with CH+ than with CH.
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Content available remote Variable Intensities of Molecular Features in the Spectrum of AE Aur
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Krełowski J. , Galazutdinov G. A. , Mulas G. , Bondar A. , Musaev F. A. , Shapovalova A. , Cecchi-Pestellini C. , Beletsky Y. , Lee B. C.
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tom Vol. 66, No. 3
391--403
EN
Using spectra of the star AE Aur (HD 34078), covering the period 1997-2015, we suggest that two strong molecular features of CH and CH+ underwent detectable changes of intensity. In the last five years both CH and CH+ declined sharply and systematically, with the CH/CH+ ratio steadily growing. No variations in the radial velocities of the observed interstellar features was detected during the covered period.
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