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1
Content available remote Relation between NH and other Simple Molecules
Weselak T.
Acta Astronomica
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2023
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Vol. 73, No. 3
233--242
EN
Relations between abundances of interstellar NH molecule and other diatomic species as OH, CH, CH+ and molecular/atomic hydrogen are presented based on 16 available sight-lines. Spacial correlations between column densities of diatomic molecules suggest that the NH molecule is rather related to interstellar CN (correlation coefficient equal to 0.82±0.09). A good relation with molecular hydrogen with correlation coefficient equal to 0.79±0.12 is also presented.
2
Content available remote 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+.
3
Content available remote Profiles of Interstellar Spectral Features Caused by Physical Parameters of Clouds
Krełowski J., Bondar A.
Acta Astronomica
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2022
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Vol. 72, No. 1
69--76
EN
The disk of our Galaxy is filled with clouds of diffuse matter, modifying spectra of distant stars. These clouds are sources of extinction, polarization and of spectral features such as atomic and molecular lines as well as the diffuse interstellar bands (DIBs), still of unknown origin, though likely molecular. Apparently physical parameters of individual translucent clouds are various. We try to provide some constraints on theoretical models of translucent interstellar clouds. It is demonstrated that intensities and profile details of DIBs can be determined using the ESPRESSO spectrograph fed by VLT. This possibility follows its very high resolution and signal-to-noise ratio, necessary to analyze atomic and molecular features, detectable in spectra of OB-stars, and originated in single (thus - likely optically thin) interstellar clouds. Our set of five high resolution (λ/δλ =140 000) ESPRESSO spectra of hot, reddened stars allows us to analyze profiles of some DIBs. It is argued that more high quality spectra from ESPRESSO are necessary to identify the DIB cariers.
4
Content available remote On the Relation between OH and CH Radicals, Molecular/Neutral Hydrogen and Major 5780/5797 Diffuse Interstellar Bands
Weselak T.
Acta Astronomica
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2022
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Vol. 72, No. 3
233--243
EN
A precise relation between column densities of OH and CH molecule in the ISM has been found based on spectra of 24 stars (four of them new) and new published oscillator strengths of lines near 3078 Å and 30828 Å of OH molecule (0.001007 and 0.0006226, respectively). Observed column density ratio of OH and CH molecules in the ISM is equal to 3.20±0.17. A very good relation (with correlation coefficient equal to 0.85) between abundances of OH molecule and molecular hydrogen is also presented.
5
Content available remote On the Relation between OH+, OH and CH+ Molecules, Neutral/Molecular Hydrogen and Major 5780/5797 DIBs
Weselak T.
Acta Astronomica
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2020
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Vol. 70, No. 4
301--312
EN
Relations between column densities of OH+, OH+ and CH+ molecules and between atomic and molecular hydrogen and intensities of major 5780 Å and 5797 Å diffuse interstellar bands are examined based on spectra of 46 stars. Data on OH+, OH, CH+ and atomic/molecular hydrogen were taken from the literature. Data on 5780 Å and 5797 Å DIBs are based mostly on our own measurements. Column densities of the OH+ are very well correlated with abundances of OH molecule and not correlated with CH+ and hydrogen in any form. Column densities of OH+ are better correlated with narrow 5797 Å than 5780 Å major DIB. The value of abundance ratio in the case of OH and OH+ molecules in the ISM is equal to 5.73±0.45.
6
Content available remote 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.
7
Content available remote 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.
8
Content available remote 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.
9
Content available remote Diffuse Interstellar Bands and Temperatures in the Interstellar Clouds
Gnaciński P., Weselak T., Krełowski J.
Acta Astronomica
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2016
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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.
10
Content available remote Consistent System of Oscillator Strengths of A2Δ-X2Π (0,0) and B2Σ--X2Π (0,0) Bands of CH Molecule
Weselak T., Galazutdinov G. A., Gnaciński P., Krełowski J.
Acta Astronomica
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2014
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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.
11
Content available remote Carriers of 4964 and 6196 Diffuse Interstellar Bands and Environments Dominated by either CH or CH+ Molecules
Weselak T., Galazutdinov G. A., Sergeev O., Godunova V., Kołos R., Krełowski J.
Acta Astronomica
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2014
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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.
12
Content available remote A Comparison of c-C3H2 and l-C3H2 in the Spiral Arm Clouds
Kulczak-Jastrzębska M., Lis D., Gerin M.
Acta Astronomica
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2012
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Vol. 62, No. 3
313--321
EN
Using the IRAM 30-m telescope, we observed molecular absorption lines from c-C3H2 produced in diffuse clouds toward the high-mass star forming regions W51 e1/e2 and W49N to determine the abundance ratio between the cyclic and linear isomers of C3H2 (Nc/Nl). The abundance ratio is found to be 3-5 in the sources where l-C3H2 was previously detected. A possible source of uncertainty in the determination of Nc/Nl is related to the estimate of N(c-C3H2). The main goal of this paper is verification of this hypothesis.
13
Content available remote Interstellar Medium in the M43 Nebula
Gnaciński P.
Acta Astronomica
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2009
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Vol. 59, No. 3
325--334
EN
We present a list of interstellar absorption lines in the direction of HD 37061 in the M43 nebula. Some of the absorption lines arise from atomic excited levels that are uncommon in interstellar clouds. The excited levels of FeII are populated by fluorescence. We found a large number of H2 molecular absorption lines arising from vibrationally excited levels. The ortho/para H2 ratio is equal to 2.7. The H2 rotational temperature of vibrational levels 1-5 exceeds 2000 K.
14
Content available remote Interstellar C2 Toward X Persei (HD 24534)
Kaczmarczyk G.
Acta Astronomica
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2000
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Vol. 50, No. 1
151--162
EN
Interstellar C2 bands D-X (2313 Å) and F-X (1342 Å) in the spectrum of X Per were detected in the archive echelle spectra acquired by the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope. The population of C2 rotational levels was determined from the rotational lines in the D-X band to obtain kinetic temperature Tk=45±15 K. The total C2 column density N(C2)=(3.4±0.5)×1013 cm-2 was calculated using the D-X band with f-value of 0.0545. The analysis of F-X band with an adopted f-value of 0.1 gave different population of rotational levels of C2. Possible reasons of this discrepancy are discussed. The FWHM of the C2 line profile was estimated to be ΔV=2.7±1.0 km/s.
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