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Yu. S. Sholudchenko I. Yu. Izotova L. S. Pilyugin 《Kinematics and Physics of Celestial Bodies》2007,23(4):163-170
We examined the Sloan Digital Sky Survey (SDSS) spectra of the H II regions in the disk of the spiral galaxy M101 (NGC 5457), and 17 H II regions with the auroral oxygen line [O III] λ 436.3 nm in their spectra were selected for line intensity measurements. The measurement data were used to determine the oxygen abundance in the H II region sample. We demonstrate that the spectral SDSS data supplemented with the information on the nebular oxygen line [O II] λ 372.7 nm based on the recently found ff-relation between the oxygen line intensities in the spectra of H II regions allow the oxygen abundance to be determined as accurately as in the standard T e method. The parameters of the radial oxygen abundance distribution in the M101 disk (the abundance at the galactic center and the radial gradient) are estimated. 相似文献
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Paleoproterozoic carbonaceous shales in the Tim-Yastrebovskii ancient rift, which underwent zonal metamorphism at 350–550°C,
contain REE mineralization of silicates (allanite, thorite, and Ce-P huttonite) fluorcarbonates (bastnaesite and synchysite),
phosphates (monazite and xenotime), and REE-bearing apatite. The reason for the wide occurrence of bastnaesite and other REE
minerals is relatively high REE concentrations in the sulfide-bearing carbonaceous shales, with these elements accumulated
in the organic matter in the course of diagenesis. Reaction textures with REE-bearing chlorite, bastnaesite, and allanite
suggest that REE-bearing chlorite and bastnaesite provided REE for the forming of higher temperature allanite and monazite.
This is corroborated by the REE patterns of the monazite, allanite, and bastnaesite, which are almost identical and are characterized
by the strong predominance of LREE. The replacements of REE minerals during metamorphism at 350–550°C took place via a number
successive transitions: (1) Mnz → Aln, Chl
REE → Bst, Chl
REE → Aln, Bst → Aln and (2) Bst → Mnz and Ap
LREE → Mnz. These replacements can be accounted for by prograde metamorphic reactions. 相似文献
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Leonid S. Pilyugin Trinh X. Thuan José M. Vílchez 《Monthly notices of the Royal Astronomical Society》2007,376(1):353-360
We search for the maximum oxygen abundance in spiral galaxies. Because this maximum value is expected to occur in the centres of the most luminous galaxies, we have constructed the luminosity – central metallicity diagram for spiral galaxies, based on a large compilation of existing data on oxygen abundances of H ii regions in spiral galaxies. We found that this diagram shows a plateau at high luminosities (−22.3 ≲ M B ≲−20.3) , with a constant maximum value of the gas-phase oxygen abundance 12 + log (O/H) ∼ 8.87 . This provides strong evidence that the oxygen abundance in the centres of the most luminous metal-rich galaxies reaches the maximum attainable value of oxygen abundance. Since some fraction of the oxygen (about 0.08 dex) is expected to be locked into dust grains, the maximum value of the true gas + dust oxygen abundance in spiral galaxies is 12 + log(O/H) ∼ 8.95. This value is a factor of ∼2 higher than the recently estimated solar value. Based on the derived maximum oxygen abundance in galaxies, we found the oxygen yield to be about 0.0035, depending on the fraction of oxygen incorporated into dust grains. 相似文献
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Leonid Pilyugin 《Astrophysics and Space Science》2003,284(2):775-778
Spiral galaxies with a reported bend in the slope of the oxygen abundance O/HR
23, derived with the traditionally used R23-method, are examined. It is shown that the artificial origin of the reported bends can be naturally explained. Two causes
of the false bend in the slope of O/HR
23 are indicated.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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New expressions for ON and NS calibrations (we call them ON11 and NS11 calibrations) for the determination of oxygen and nitrogen abundances in HII regions are proposed. New criteria for the division of HII regions into three classes (hot, warm, and cold) are also proposed. ON11 and NS11 calibrations provide more accurate determination of oxygen and nitrogen abundances from integrated emission spectra, in comparison with ON and NS calibrations. Oxygen and nitrogen abundances are estimated for a sample of 57 470 SDSS galaxies using ON11 and NS11 calibrations. Strongline flux measurements for SDSS spectra of these galaxies are taken from the MPA/JHU catalog. A ??mass-metallicity?? diagram for several redshift ranges is constructed. It is found that the interstellar medium of galaxies with high masses log(M/M ??) > 11.3 was hardly enriched with either oxygen or nitrogen over the last 4 Gyrs (corresponding to the redshift interval z = 0?C0.4). This indicates that an active stage of star formation in massive galaxies was completed more than 4 Gyrs ago. For galaxies of lower masses, changes in oxygen and nitrogen abundances over the time period under consideration increase as galaxy mass decreases. 相似文献
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L. S. Pilyugin I. A. Zinchenko T. X. Thuan 《Kinematics and Physics of Celestial Bodies》2010,26(5):215-232
A sample of 93 emission-line high luminosity galaxies from the Sloan Digital Sky Survey (SDSS) has been investigated. Line
intensities have been measured in 116 SDSS spectra. Oxygen abundance has been determined in the studied galaxies. Since the
auroral line of twice ionized oxygen [O III] λ 436.3 nm cannot be detected in the spectra of the sample, the intensity ratio
of nebular to auroral lines needed to determine the electron temperature is calculated using the ff-relation. The oxygen abundances obtained in SDSS high luminosity galaxies are 0.2–0.5 dex lower than the maximum attainable
value. This is caused by the fact that the sample includes only the gas-rich galaxies in which intense bursts of star formation
occur. The equivalent number of O7 V stars which are responsible for excitation of luminescent H II regions in the studied
sample is two or three orders of magnitude more than the number of stars which cause the luminescence of the brightest H II
regions in nearby galaxies, and it exceeds by one order of magnitude the number of stars which cause gas in SBS 0335-052 E
to glow. 相似文献
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B. Ya. Melekh L. S. Pilyugin R. I. Korytko 《Kinematics and Physics of Celestial Bodies》2012,28(4):189-202
The method of determination of heavy element abundances in H II regions (the strong-line method) uses the assumption that some combinations of strong emission line intensities in spectra of H II regions can serve as indicators of metallicities and electron temperatures in nebulosities. Three sets of strong lines are considered, namely, A (R 3, R 2, N 2, S 2 lines), B (R 3, R 2, N 2 lines), and C (R 3, N 2, S 2 lines). Strong line intensities are normalized to the H ?? intensity). We searched for an unambiguous relationship between strong emission line intensities of these line sets in spectra of H II regions and their compositions. The extensive model grid for H II regions is computed. Chemical compositions of nebulosities and intensities of A and C lines are shown to be related unambiguously. For the B line set, 5% of model H II regions do not have any unambiguous relationship, namely, the models with appreciably different oxygen and nitrogen abundances in H II regions can have similar intensities of the B set lines. The versions of strong-line method (calibrations) using the A and C lines are more reliable than those based on the B lines. 相似文献