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1

Buckminster Fullerene and Interstellar Extinction

Gnaciński P.

Acta Astronomica

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2023

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Vol. 73, No. 2

179--186

EN

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+.

2

On the Relation between Interstellar Spectral Features and Reddening

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

Acta Astronomica

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2019

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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.

3

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

Galazutdinov G. A., Krełowski J.

Acta Astronomica

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2017

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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.

4

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

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

Acta Astronomica

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2017

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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.

5

Observations of HDO in the High-Mass Star Forming Regions

Kulczak-Jastrzębska M.

Acta Astronomica

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2016

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Vol. 66, No. 2

239--254

EN

I present observations of the ground state (10,1-00,0) rotational transition of HDO at 464.925 GHz toward several high-mass star forming regions carried out with the Caltech Submillimeter Observatory. The spectra are modeled together with observations of higher-energy HDO transitions and submillimeter dust continuum fluxes present in the literature. Spherically symmetric radiative transfer model was used to derive the radial distribution of the HDO abundance in the target sources. The abundance profile is divided into an inner hot core region, with kinetic temperatures higher than 100 K, and a cold outer envelope. The derived HDO abundances relative to H2 are: (0.6-3.5)×10-8 and (0.1-25)×10-11 in the hot inner region and the cold outer envelope, respectively.