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5 Acta Astronomica

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Looking for the Weak Members of the C60+ Family in the Interstellar Medium

100%

Galazutdinov G. A. , Krełowski J.

2017

tom Vol. 67, No. 2

159--169

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.

On the Relation between Interstellar Spectral Features and Reddening

80%

Krełowski J. , Galazutdinov G. , Godunova V. , Bondar A.

Acta Astronomica

2019

tom Vol. 69, No. 2

159--175

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.

On the Relations between Carriers of Interstellar Absorptions

80%

Krełowski J. , Strobel A.

Acta Astronomica

2024

tom Vol. 74, No. 1

69--76

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

Buckminster Fullerene and Interstellar Extinction

80%

Gnaciński P.

Acta Astronomica

2023

tom Vol. 73, No. 2

179--186

Most of over 500 Diffuse Interstellar Bands (DIBs) can not be assigned to any carrier. Only the infrared DIBs at 9348-9632 Å are known to be absorption lines of the buckminster fullerene cation C60+. We show that equivalent width of the 9577 Å DIB is correlated with the bump area on the ultraviolet extinction curve and with interstellar reddening E(B-V). Physical conditions must be similar for forming dust particles responsible for the UV-bump and forming C60+.

Constant Intensities of Diffuse Interstellar Bands in the Spectrum of AE Aur

80%

Krełowski J. , Galazutdinov G. A. , Bondar A. , Byeong-Cheol L.

2017

tom Vol. 67, No. 1

71--80

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.