Supporting: 14, Disputing: 3, Mentioning: 59 - ABSTRACTWe present a study of the three forbidden oxygen lines [OI] located in the optical region -i.e., 5577.339 Å (the green line), 6300.304 Å and 6363.776 Å (the two red lines) -in order to better understand the production of these atoms in cometary atmospheres. Search for other works by this author on: Oxford Academic. : Univ. ► We present observations of the atomic oxygen lines in Comet 103P/Hartley. Before spectra of oxygen ions became known, these lines once led to a spurious identification of the substance as a new chemical element. (2019) have observed several atomic oxygen (5577, 6300, & 6364 Å), carbon (8727, 9824, & 9850 Å) and nitrogen (5197 & 5200 Å) forbidden emission lines in C/2016 R2. The CO2/H2O ratio in 103P was also observed by the DIXI spacecraft to vary significantly with rotational phase of the nucleus, which explains the large range of oxygen line ratios observed. A large fraction of the more highly excited By continuing you agree to the use of cookies. De Keyser. Forbidden oxygen lines in the spectrum of 153P/2002 C1 (Ikeya-Zhang) January 2005; Authors: Maria Teresa Capria. 1 shows the electronic transitions of these forbidden emission lines. It is shown that the electric-field fluctuations give rise to satellite lines which are disposed symmetrically in pairs about the forbidden line and separated from it by 3Ω, where Ω is the plasma frequency. The term forbidden is misleading; a more accurate description would be … Its emission forbidden lines in the visible spectrum fall primarily at the wavelength 500.7 nm, and secondarily at 495.9 nm. The forbidden oxygen lines are also present as telluric emission features, therefore a combination of high spectral resolution and large geocentric velocity (and therefore large Doppler shift) is needed to resolve the cometary lines from the telluric features. forbidden oxygen lines in the inner coma of 67P/Churyumov-Gerasimenko. ► We confirm the idea that the oxygen lines are sensitive to the CO2 abundance. Krasnopolskii, V. A. Abstract. Politique de confidentialité FILMube . Oxygen is an important element in the chemistry of the solar system objects given its abundance and its presence in many molecules including H2O 80% of cometary ices). The ground configurations of OI, 011, NI, and Nil are each composed of three terms. forbidden lines Lines that are not found in spectra under normal terrestrial conditions but are observed in certain astronomical spectra. Numbering these terms I, 2, and 3 for the lowest, middle, and We aim to explore the photochemistry of all these forbidden atomic oxygen emissions ([OI] 2972, 5577, 6300, 6464 Å) in the Martian daylight upper atmosphere and suitable conditions for the simultaneous detection of these emissions lines in the dayside visible spectra. This was the main reason why the total number of stars with determined carbon and oxygen abundances was lower than that for lithium. In astronomy and atomic physics, doubly ionized oxygen is the ion O 2+ (also known as O III in spectroscopic notation).Its emission forbidden lines in the visible spectrum fall primarily at the wavelength 500.7 nm, and secondarily at 495.9 nm. state by forbidden radiation. 40.79; National Institute of Astrophysics; Gabriele Cremonese. We present observations and analysis of the forbidden oxygen lines in Comets C/2006 W3 (Christensen) and C/2007 Q3 (Siding Spring) at heliocentric distances of 3.13 and 2.96 AU, respectively. Three forbidden oxygen emission lines in optical region, the green line at 557.7330 nm (from 1 S to 1 D meta-stable state) and the red doublet lines at 630.0304 and 636.3776 nm (from 1 D meta-stable state to 3 P state) were observed. 2015; McKayetal.2015),andbymodelling(seee.g.Bhardwaj&Raghu-ram 2012, and references therein). A forbidden line arises when an electron in an excited (energized) atom jumps from a metastable state to a lower energy level. for 90% or more of the total visual brightness of an object such as a planetary We consider only the impact of the solar UV flux on the production of the three forbidden oxygen lines of interest. And in fact, globe valves are forbidden to be used either for the same reason. photon. The ground configurations of OI, 011, NI, and Nil are each composed of three terms. and parts of active galactic nuclei. Under normal Copyright © 2020 Elsevier B.V. or its licensors or contributors. 2015), and by modelling (see e.g. out of its metastable state by collision and not be given time to emit a A comparison of calculations and measurements of the 2972 and 6300/64 A lines is spectra of comet Bradfield shows that the yield of singlet states of atomic oxygen during the dissociation of H2O in the 1216 A line and the neighboring spectral region is about 10 percent. Decock et al. spectrum (to which the human eye is most sensitive) at 4959 and 5007 Å. Forbidden Atomic Oxygen and Nitrogen Lines The spectroscopic nomenclature adopted in this book is summarized in Sec­ tion 1.1.2. KW - Comets, Composition A theory is given for the effect of very strong stochastic electric fields on forbidden lines of atomic absorption spectra. Since these emissions originate from metastable allowed transitions from higher states, they remain there undisturbed until In astronomy and atomic physics, doubly ionized oxygen is the ion O (also known as O III in spectroscopic notation). Before spectra of oxygen ions became known, these lines once led to a spurious identification of the substance as a new chemical element. Therefore, the forbidden oxygen emission lines are dealt with the tracer of water molecules in the coma. osti.gov journal article: auroral excitation of the forbidden lines of atomic oxygen. The excited oxygen states come mainly from the photodisso-ciation of H 2O, CO 2,O 2, and CO as suggested both by remote observations of atomic oxygen lines (see e.g. According to the regulations of valve materials in GB 16912 Oxygen and Related Gas Safety Technical Regulations, when the pressure is greater than 0.1MPa, it is strictly forbidden to use gate valves.When the pressure is between 0.1 and 0.6MPa, the valve disc should be made from stainless steel. PY - 2012/7. Various forbidden atomic emission lines of [CI], [NI], and [OI] were observed in the optical spectrum of this comet when it was at 2.8 au from the Sun. forbidden lines Lines that are not found in spectra under normal terrestrial conditions but are observed in certain astronomical spectra. Decock et al. Forbidden lines are denoted by enclosing them in brackets. KW - Comets, Coma. But in an environment like that of a planetary nebula, the time 1 Space Physics Division, Royal Belgian Institute for Space Aeronomy, Ringlaan 3, B-1180 Brussels, Belgium ★ E-mail: gael.cessateur@aeronomie.be. AURORAL EXCITATION OF THE FORBIDDEN LINES OF ATOMIC OXYGEN. Forbidden Atomic Oxygen and Nitrogen Lines The spectroscopic nomenclature adopted in this book is summarized in Sec­ tion 1.1.2. High spatial resolution observations of comet Bradfield (1979X) with the IUE spectrograph have made it possible to tentatively identify a feature at 2972 A as the 1S-3P forbidden transition of oxygen atoms. Oxygen is an important element in the chemistry of the Solar System objects given its abundance and its presence in many molecules including H2O, which constitutes 80% of cometary ices. Forbidden oxygen lines at various nucleocentric distances in comets Decock A. Jehin E. Rousselot P. 1 Hutsemékers D. Manfroid J. Raghuram S. Bhardwaj A. Hubert B. Détails. The excited oxygen states come mainly from the photodissociation of H 2 O, CO 2, O 2, and CO as suggested both by remote observations of atomic oxygen lines (see e.g. These observations of the forbidden oxygen lines in 103P, a comet for which a directly observed CO2/H2O ratio is available, suggest that high quality observations of the forbidden oxygen lines in comets can serve as a proxy for CO2/H2O ratio measurements. In the above figure of the oxygen spectrum these lines are not present at all! Consequently, narrow band-pass filtersthat isolate the 501 nm and 496 n… Abstract. More than half a century To study the formation of the [OI] lines - i.e., 5577 A (the green line), 6300 A and 6364 A (the two red lines) - in the coma of comets and to determine the parent species of the oxygen atoms using the green to red-doublet emission intensity ratio (G/R ratio) and the lines velocity widths. 2015; McKay et al. Copyright © 2012 Elsevier Inc. All rights reserved. This advanced XML editor provides the most intuitive tools for XML editing, authoring, and development. AU - McKay, Adam J. 2D photochemical model for forbidden oxygen line emission for comet 1P/Halley G. Cessateur. ions eventually drop into these states and, in a nebular environment, practically Forbidden lines of oxygen in comet spectra Krasnopolskiy, V. A. Abstract. The NLTE effects affecting oxygen-abundance determinations of solar-type stars are discussed. Lines that are not present at all G. Cessateur Editor for Windows, Mac, and Nil each. The solar UV flux on the Opitom et al Jeffrey P. AU - Morgenthaler, Jeffrey P. AU Russo... An environment like that of a couple-chemistry emission model Walker, J C.G from metastable. Lines in the framework of a couple-chemistry emission oxygen forbidden lines chemical element present at all the Astrophysical Consortium...: Oxford Academic spurious identification of the three forbidden oxygen lines of oxygen atoms in comets provide. 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