Molecular absorption in transition region spectral lines
نویسندگان
چکیده
منابع مشابه
Properties of the Lower Transition Region: the Widths of Optically Allowed and Intersystem Spectral Lines
The widths of spectral lines in the ultraviolet (UV) and extreme ultraviolet (EUV) spectral regions that are formed in the solar transition region and corona are usually greater than the optically thin widths due to thermal Doppler broadening calculated under the assumption of ionization equilibrium. Although opacity can explain the widths of some lines, there are a host of optically thin lines...
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The four known molecular absorption line systems at redshifts z=0.25–0.89 are discussed. Two of the systems originate in the galaxy hosting the ‘background’ AGN, while in two cases the absorption occurs in truely intervening galaxies. Indirect evidence for the existence of very small scale structure in the molecular ISM is presented. A new absorption line at z=0.89 towards PKS1830–211 opens up ...
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We address the hypothesis that downdrafts driven by radiatively-cooling condensations in the solar transition region are able to produce significant redshifts in UV lines as frequently observed on the solar disk and, more recently, on other stars. In a first paper, significant redshifted line components at several km/s have been found from modeling the evolution of an isobaric perturbation twic...
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We have obtained short exposure (3 s) time series of strong upper chromospheric and transition region emission lines from the quiet Sun with the SUMER instrument onboard SOHO during two 1 hour periods in 1996. With a Nyqvist frequency of 167 mHz and relatively high count rates the dataset is uniquely suited for searching for high frequency variations in intensity and Doppler velocity. From Mont...
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We present the results of a z > 2.9 survey for H I 21-cm and molecular absorption in the hosts of radio quasars using the Giant Metrewave Radio Telescope and the Tidbinbilla 70m telescope. Although the atomic gas has been searched to limits capable of detecting most known absorption systems, no H I was detected in any of the ten sources. Previously published searches, which are overwhelmingly a...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2014
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361/201424432