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1.
We present the results of U BV RI CCD photometry of giant HII regions in the spiral galaxy NGC 628, acquired with the 1.5 m telescope of the Mt. Maidanak Observatory (Uzbekistan) with an angular resolution better than 1″. We estimate the ages and interstellar extinctions of these regions and identify the acting star-formation mode by comparing the observed color indices with a detailed grid of evolutionary models covering the entire range of parameters of the initial mass function and of ages of the young star-formation complexes, and taking into account two star-formation modes. We find a radial gradient of the interstellar extinction in NGC 628, which is consistent with the radial abundance gradient found earlier by other authors from independent spectrophotometry. Our age estimates agree with abundance estimates from independent observations. 相似文献
3.
Amethod for determining the most probable spectral types, color excesses E B-V , and distances of stars from multicolor photometry is described. The main idea of the method is modeling the photometric data using various models for the stellar spectra and the interstellar extinction law, and applying the maximum likelihood method. The reliability of the method is estimated using stars with known spectral types and WBVR photometry, based on the empirical library of stellar spectra of Pickles and the model for the interstellar extinction law developed by Fluks et al. 相似文献
4.
The results of multicolor surface photometry of the S0 galaxies NGC 524, NGC 1138, and NGC 7280 and the spiral galaxies NGC 532, NGC 783, and NGC 1589 are reported. U BV RI observations were acquired with the 1.5-m telescope of the Maidanak Observatory (Uzbekistan), while JHK data were taken from the 2MASS catalog. The overall structure of the galaxies is analyzed and the galaxy images decomposed into bulge and disk components. The parameters of the galaxy components—rings, bars, spiral arms, and dust lanes—are determined. The bulge/disk decompositions based on averaged one-dimensional photometric profiles yield incorrect parameters for the bulges of the S0-Sa galaxies with bars and/or rings, whose inner regions are dominated by the radiation of the bulge. 相似文献
5.
Results of numerical simulations of a collision of the gaseous components of two identical disk galaxies during a head-on
collision of the galaxies in the polar direction are presented. When the relative velocity of the galaxy collision is small,
their gaseous components merge. At high relative velocities (100–500 km/s), the massive stellar components of the galaxies
( M
g
= 10 9
M
⊙) pass through each other nearly freely, leaving behind the gaseous components, which are decelerated and heated by the collision.
If the overall gaseous component of the colliding galaxies is able to cool to the virial temperature during the collision,
a new galaxy forms. At velocities V ≥ 500 km/s, the gaseous component does not have time to cool, and the gas is scattered into intergalactic space, supplying
it with heavy elements produced in supernovae in the colliding galaxies. High-velocity ( V ≥ 100 km/s) collisions of identical low-mass galaxies ( M
g
≤ 10 9
M
⊙) whose mass is dominated by the mass of gas lead to the disruption of their stellar components. The overall gaseous component
forms a new galaxy when V ≤ 500 km/s, and is scattered into intergalactic space if the velocity becomes higher than this. A galaxy collision increases
the star-formation rates in the disk galaxies by nearly a factor of 100. Rotation of the colliding galaxies in the same direction
increases the changes of the disruption of both the stellar and gaseous components of the galaxies. The merger of galaxies
during their collision can explain the presence of gaseous disks rotating opposite to the rotation of the stellar component
in some ordinary elliptical galaxies. Moreover, galaxy mergers can help explain the origin of a comparatively young stellar
population in some elliptical galaxies. 相似文献
6.
The parameters of the radiation of interstellar matter in star-forming complexes in the high-metallicity galaxies NGC 628, NGC 2976, and NGC 3351, which have different morphological types, are analyzed. The relationship between the emission in Hα and in lines of CO and HI is considered, as well as the relationship between Hα and the emission of dust in the infrared range (IR). The fluxes and surface brightnesses in the UV and IR correlate well with the Hα emission. The HI emission also correlates well with Hα, while the correlation between the CO and Hα emission is much weaker. The ratio of the fluxes at 8 and 24 µm decreases with increasing Hα flux. This may be due to changes in the properties of the dust ensemble (a decrease in the mass fraction of polycyclic aromatic hydrocarbons) or to changing excitation conditions. Analysis of the kinematics of the CO lines shows that the CO flux grows with increasing velocity scatter ΔV when ΔV ? 70 km/s. Preliminary evidence for the existence of star-forming complexes with higher values of ΔV is provided, when the increase in the velocity scatter is accompanied by a decrease in the CO luminosity of the complex. 相似文献
7.
Most altered clay minerals in uranium ore deposits in granites in the selected provinces of South China have δ
18O
m
values ranging from 6.22 to 7.24, δD m from −60 to −70, δ
18O
from +3.05 to −3.07, and
from −20.2 to −37.5‰. Relative enrichment of 32S in the uranium ore deposits and greater variations in Pb isotopic composition of galenas from them show that uranium ores
in the granites were formed in such a way that uranium in shallow-source granites had been mobilized by heated meteoric waters
and then migrated to local favourable locations along great faults to form uranium ore deposits.
Zhang Shaoli, Yang Wenjin, Tang Chunjing and Xu Wenxin did part of this work. 相似文献
8.
Britvinite, a new mineral species, has been found in manganese ore at the Långban deposit, Bergslagen ore district, Filipstad, Värmland County, Sweden. Calcite, barytocalcite, brucite, cerussite, and hausmannite are associated minerals. Britvinite occurs as pale yellow to colorless transparent plates with a white streak up to 0.2 × 0.5 × 0.5 mm in size, which are flat parallel to {001}; the luster is adamantine. Thin lamellae are flexible, whereas thick ones are brittle; the Mohs hardness is 3. The cleavage is eminent parallel to {001}. The calculated density is 5.51 g/cm 3. In the infrared spectrum of the new mineral, the bands of (OH)?, (CO 3) 2?, and (BO 3) 3? are recorded, whereas those corresponding to water molecules are absent. Britvinite is optically biaxial and negative, α = 1.896(2), β = 1.903(2), γ = 1.903(2), 2 Vmeas = 20(10), Z≈ c. Dispersion is strong, r< v. The chemical composition (electron microprobe; H 2O determined with the Alimarin method, CO 2, with selective sorption) is (wt %) 7.95 MgO, 71.92 PbO, 0.41 Al 2O 3, 12.77 SiO 2, 2.2 H 2O, 2.1 CO 2, 2.67 B 2O 3 (calculated on the basis of structural data); total 100.02. The empirical formula calculated on the basis of 59 anions (O + OH) ( Z = 1) is as follows: Pb 14.75Mg 9.03Si 9.73Al 0.37O 30.76(BO 3) 3.51(CO 3) 2.18(OH) 11.7. The simplified formula ( Z = 2) is Pb 7 + x Mg 4.5(Si 5O 14)(BO 3) 2(CO 3)(OH,O) 7 ( x < 0.5). The crystal structure of britvinite has been studied on a single crystal at 173 K; R = 0.0547. The new mineral is triclinic, space group P $ \bar 1 Britvinite, a new mineral species, has been found in manganese ore at the L?ngban deposit, Bergslagen ore district, Filipstad,
V?rmland County, Sweden. Calcite, barytocalcite, brucite, cerussite, and hausmannite are associated minerals. Britvinite occurs
as pale yellow to colorless transparent plates with a white streak up to 0.2 × 0.5 × 0.5 mm in size, which are flat parallel
to {001}; the luster is adamantine. Thin lamellae are flexible, whereas thick ones are brittle; the Mohs hardness is 3. The
cleavage is eminent parallel to {001}. The calculated density is 5.51 g/cm3. In the infrared spectrum of the new mineral, the bands of (OH)−, (CO3)2−, and (BO3)3− are recorded, whereas those corresponding to water molecules are absent. Britvinite is optically biaxial and negative, α
= 1.896(2), β = 1.903(2), γ = 1.903(2), 2Vmeas = 20(10), Z≈c. Dispersion is strong, r<v. The chemical composition (electron microprobe; H2O determined with the Alimarin method, CO2, with selective sorption) is (wt %) 7.95 MgO, 71.92 PbO, 0.41 Al2O3, 12.77 SiO2, 2.2 H2O, 2.1 CO2, 2.67 B2O3 (calculated on the basis of structural data); total 100.02. The empirical formula calculated on the basis of 59 anions (O
+ OH) (Z = 1) is as follows: Pb14.75Mg9.03Si9.73Al0.37O30.76(BO3)3.51(CO3)2.18(OH)11.7. The simplified formula (Z = 2) is Pb7 + x
Mg4.5(Si5O14)(BO3)2(CO3)(OH,O)7 (x < 0.5). The crystal structure of britvinite has been studied on a single crystal at 173 K; R = 0.0547. The new mineral is triclinic, space group P
; the unit-cell dimensions are a = 9.3409(8), b = 9.3597(7), c = 18.8333(14) ?, α = 80.365(6)°, β = 75.816(6)°, γ = 59.870(5)°, V = 1378.74(19) ?3. The structure consists of alternating TOT stacks (containing octahedral brucite-like and discontinuous tetrahedral (Si5O14)∞∞ layers) and multilayered [Pb7.1(OH)3.6(CO3)(BO3)1.75(SiO4)0.25]∞∞ blocks. The strongest reflections in the X-ray powder diffraction pattern [d, ? (I, %)(hkl)] are 18.1(100)(001), 3.39(30)(12, 14, 015), 3.02(90)(006, 130, 106, 20, 11), 2.698(70)(332, 134, 030, 1), 2.275(30)(008, 420, 424), 1.867(30)(446, 239, 2.1.10, 18), 1.766(40)(151, 31, 10, 453, 542, 512, 42), 1.519(40)(0.0.12). The mineral has been named in honor of Sergei Nikolaevich Britvin (b. 1965), a Russian mineralogist.
The type material of britvinite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow. The
registration number is 3458/1.
Original Russian Text ? N.V. Chukanov, O.V. Yakubovich, I.V. Pekov, D.I. Belakovsky, W. Massa, 2007, published in Zapiski
Rossiiskogo Mineralogicheskogo Obshchestva, 2007, Pt CXXXVI, No. 6, pp. 18–25.
The new mineral britvinite and its name were accepted by the Commission on New Minerals and Mineral Names, Russian Mineralogical
Society, June 7, 2006, and approved by the Commission on New Minerals and Mineral Names, International Mineralogical Association,
October 17, 2006. 相似文献
9.
We use UBVRI CCD photometry to study star-forming regions (SFRs) in the galaxies NGC 5585 and IC 1525. The observations were acquired
with the 1.5-m telescope of the Mt. Maidanak Observatory of the Astronomical Institute of the Uzbek Academy of Sciences (Uzbekistan),
with seeing of 0.8″–1.8″. We identified 47 SFRs in NGC 5585 and 16 SFRs in IC 1525. We estimated the ages and internal extinctions
of the SFRs using the PEGASE2 evolution models. The sizes of the SFRs were also determined. We discuss in detail the techniques
applied to evaluate the SFR parameters from photometric analysis. The age range for the studied SFRs is (2–40) × 10 6 yrs, and the internal extinctions are A( V ) ≤ 1.5 m. The age distributions of the SFRs in both galaxies are typical of stellar systems with intense, extended star formation.
The internal extinction in the SFRs decreases with distance from the galactic centers: A( V ) ∝ − r. For both galaxies, the scale length for the decrease of the dust surface density, estimated from the A( V )− r relation for SFRs, is close to the scale length for the disk brightness decrease in the V and R bands. Relatively larger and older SFRs are observed in the galaxies’ rings, while such SFRs are not found in the spiral
arms. We detected different SFR parameters for different spiral arms of NGC 5585. 相似文献
10.
The paper reports the results of BV RI surface photometry of the giant galaxy NGC 5351 based on CCD observations obtained on the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. Analysis of the structure and radial brightness distribution in the galaxy shows that NGC 5351 has a complex and, in some places, asymmetric structure. The galaxy possesses a large quantity of dust. The average internal extinction due to dust is AV=1.2 m±0.4 m. After correcting for the effect of this dust, the parameters of the galaxy are typical of late-type spirals. The compositions of the stellar population in various parts of the galaxy are estimated using two-color diagrams. Star-forming regions in NGC 5351 are identified and studied. Most of the star-forming regions are located in the ring of the galaxy. Evolutionary modeling is used to estimate the ages of regions of violent star formation. An elliptical companion galaxy to NGC 5351 was found. The rotation curve of the galaxy is modeled and its mass estimated. The disk of NGC 5351 is self-gravitating within its optical radius. 相似文献
11.
Hubble Space Telescope archive data are used to perform photometry of stars in seven fields at the center and periphery of the galaxy NGC 2366. The variation of the number density of stars of various ages with galactocentric radius and along the minor axis of the galaxy are determined. The boundaries of the thin and thick disks of the galaxy are found. The inferred sizes of the subsystems of NGC 2366 ( Z thin = 4 kpc and Z thick = 8 kpc for the thin and thick disks, respectively) are more typical for spiral galaxies. Evidence for a stellar halo is found at the periphery of NGC 2366 beyond the thick disk of the galaxy. 相似文献
12.
The four well studied spiral galaxies M33, M81, M100, and M101 are used to analyze the dependences of the star-formation rate (SFR) and star-formation efficiency (SFE = SFR/ M gas ) on galactocentric distance R and the photometric and some kinematic parameters of galactic disks. The dependences SFR( R) were estimated based on UV and far-infrared data using published extinction-corrected UV brightness profiles of the galaxies. The local SFE values are most closely related to the surface brightness (density) of the galactic disk at a given R, with this dependence being the same for all four galaxies (except for their central regions). In order to explain the observed disk densities in terms of a simple conservative model (“toy model”) for the evolution of the gas density, the local value of the parameter N in the Schmidt law for the disk (SFR ~ σ gas N ) must not exceed unity. In this case, the observed dependences σ gas ( R) and SFE( R) can be matched assuming that accretion is occuring in the central regions of the disks. 相似文献
13.
Data on about forty virialized galaxy clusters with bright central galaxies, for which both the galactic velocity dispersion ( ?? gal) and the stellar velocity dispersion in the brightest galaxies ( ??*) are measured, have been used to obtain several approximate relations between ?? gal, ??*, the absolute B magnitude of the brightest central galaxy M B BCG , and the mass of the central massive black hole M BH: $\begin{gathered} \log \sigma _* = (0.12 \pm 0.14)\log \sigma _{gal} + (2.1 \pm 0.4), \hfill \\ \log \sigma _* = - (0.15 \pm 0.02)M_B^{BCG} + (0.85 \pm 0.5), \hfill \\ \log M_{BH} = 0.51\log \sigma _{gal} + 7.28. \hfill \\ \end{gathered} $ . These relations can be used to derive crude estimates of MBH in the nuclei of the brightest galaxies using the parameters of the both host galaxies and the host galaxy clusters. The last relation above confirms earlier suggestions of a quadratic relation between the masses of the coronas of the host systems and the masses their central objects: M hg halo ?? M cent 2 . The relations obtained are consistent with the common evolution of subsystems with different scales and masses formed in the process of hierarchical clustering. 相似文献
14.
The temperature dependences of the crystal structure and intensities of the (113) and (211) reflections in calcite, CaCO 3, were studied using Rietveld structure refinements based on synchrotron powder X-ray diffraction data. Calcite transforms
from to at about T
c = 1,240 K. A CO 3 group occupies, statistically, two positions with equal frequency in the disordered phase, but with unequal frequency in the partially ordered phase. One position for the CO 3 group is rotated by 180° with respect to the other. The unequal occupancy of the two orientations in the partially ordered
phase is obtained directly from the occupancy factor, x, for the O1 site and gives rise to the order parameter, S = 2 x − 1. The a cell parameter shows a negative thermal expansion at low T, followed by a plateau region at higher T, then a steeper contraction towards T
c, where the CO 3 groups disorder in a rapid process. Using a modified Bragg–Williams model, fits were obtained for the order parameter S, and for the intensities of the (113) and (211) reflections.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
We have analyzed the radial scales, central surface brightnesses, and colors of 400 disks of various types of galaxies. For nine galaxies, the brightness decrease and the central disk brightness were obtained via a two-dimensional decomposition of the U BV RI J H K photometric images into bulge and disk components. We used published disk parameters for 392 of the galaxies. The central surface brightness μ 0,i 0 and linear (disk) scale length h vary smoothly along the Hubble sequence of galaxies within a rather narrow interval. The disks of relatively early-type galaxies display higher central K surface brightnesses, higher central surface densities, higher central mass-to-luminosity ratios M/L( B), smaller sizes (relative to the diameter of the galaxy D 25), redder integrated colors, and redder central colors. The color gradient normalized to the radius of the galaxy and the “blue” central surface brightness of the disk, μ 0,i/0( B), are both independent of the galaxy type. The radial disk scales in different photometric bands differ less in early-type than in late-type galaxies. A correlation between the central disk surface brightness and the total luminosity of the galaxy is observed. We also consider the influence of dust on the photometric parameters of the disks. 相似文献
16.
The thermodynamic stability constants for the hydrolysis and formation of mercury (Hg 2+) chloride complexes
have been used to calculate the activity coefficients for Hg(OH)
n
(2–n)+ and HgCl
n
(2–n)+ complexes using the Pitzer specific interaction model. These values have been used to determine the Pitzer parameters for
the hydroxide and chloro complexes and C
ML). The values of and have been determined for the neutral complexes (Hg(OH) 2 and HgCl 2). The resultant parameters yield calculated values for the measured values of log to ±0.01 from I = 0.1 to 3 m at 25°C. Since the activity coefficients of and are in reasonable agreement with the values for Pb(II), we have estimated the effect of temperature on the chloride constants
for Hg(II) from 0 to 300°C and I = 0–6 m using the Pitzer parameters for complexes. The resulting parameters can be used to examine the speciation of Hg(II) with Cl − in natural waters over a wide range of conditions. 相似文献
17.
Elpasolite, K 2NaAlF 6, has been found for the first time in a pegmatite related to peralkaline foid syenite at Mt. Koashva, Khibiny alkaline pluton, Kola Peninsula, Russia, as pale pink octahedral crystals up to 2 mm in size within cavities in the natrolite core of pegmatite in association with amicite, sodalite, aegirine, pectolite, catapleiite, sitinakite, lemmleinite-K, and vinogradovite. The chemical composition determined with an electron microprobe is as follows, wt %: 31.53 K; 9.22 Na; 11.20 Al; 47.21 F; total is 99.16. The empirical formula is K 1.96Na 0.98Al 1.01F 6.05. The infrared spectrum is given. The crystal structure has been refined to R = 0.030, space group Fm $ \bar 3 Elpasolite, K2NaAlF6, has been found for the first time in a pegmatite related to peralkaline foid syenite at Mt. Koashva, Khibiny alkaline pluton,
Kola Peninsula, Russia, as pale pink octahedral crystals up to 2 mm in size within cavities in the natrolite core of pegmatite
in association with amicite, sodalite, aegirine, pectolite, catapleiite, sitinakite, lemmleinite-K, and vinogradovite. The
chemical composition determined with an electron microprobe is as follows, wt %: 31.53 K; 9.22 Na; 11.20 Al; 47.21 F; total
is 99.16. The empirical formula is K1.96Na0.98Al1.01F6.05. The infrared spectrum is given. The crystal structure has been refined to R = 0.030, space group Fm
m, a = 8.092 ?. The result of a special X-ray powder diffraction study confirmed the suggestion made by Morss (1974) that reflections
violating space group Fm
m in some published X-ray powder patterns of natural elpasolite are Kβ-lines.
Original Russian Text ? I.V. Pekov, N.V. Chukanov, N.N. Kononkova, N.V. Zubkova, M.Kh. Rabadanov, D.Yu. Pushcharovsky, 2007,
published in Zapiski Rossiiskogo Mineralogicheskogo Obshchestva, 2007, No. 6, pp. 76–84. 相似文献
18.
An analysis of high-resolution CCD spectra of the giant 25 Mon, which shows signs of metallicity, and the normal giant HR 7389 is presented. The derived effective temperatures, gravitational accelerations, and microturbulence velocities are Teff = 6700 K, log g = 3.24, and ξ t = 3.1 km/s for 25 Mon and Teff = 6630 K, log g = 3.71, and ξ t = 2.6 km/s for HR 7389. The abundances (log ε) of nine elements are determined: carbon, nitrogen, oxygen, sodium, silicon, calcium, iron, nickel, and barium. The derived excess carbon abundances are 0.23 dex for 25 Mon and 0.16 dex for HR 7389. 25 Mon displays a modest (0.08 dex) oxygen excess, with the oxygen excess for HR 7389 being somewhat higher (0.15 dex). The nitrogen abundance is probably no lower than the solar value for both stars. The abundances of iron, sodium, calcium (for HR 7389), barium, and nickel exceed the solar values by 0.22–0.40 dex for both stars. The highest excess (0.62 dex) is exhibited by the calcium abundance for 25 Mon. Silicon displays a nearly solar abundance in both stars—small deficits of ?0.03 dex and ?0.07 dex for 25 Mon and HR 7389, respectively. No fundamental differences in the elemental abundances were found in the atmospheres of 25 Mon and HR 7389. Based on their Teff and log g values, as well as theoretical calculations, A. Claret estimated the masses, radii, luminosities, and ages of 25 Mon ( M/M⊙ = 2.45, log( R/R⊙) = 0.79, log( L/L⊙) = 1.85, t = 5.3 × 10 8 yr) and HR 7389 ( M/M⊙ = 2.36, log( R/R⊙) = 0.50, log( L/L⊙) = 1.24, t = 4.6 × 10 8 yr), and also of the stars 20 Peg ( M/M⊙ = 2.36, log( R/R⊙) = 0.73, log( L/L⊙) = 1.79, t = 4.9 × 10 8 yr) and 30 LMi ( M/M⊙ = 2.47, log( R/R⊙) = 0.73, log( L/L⊙) = 1.88, t = 4.8 × 10 8 yr) studied by the author earlier. 相似文献
19.
Olivine crystals were grown in the presence of a hydrous silicate fluid during multi-anvil experiments at 8 GPa and 1,000–1,600°C.
Experiments were conducted both in a simple system (FeO–MgO–SiO 2–H 2O) and in a more complex system containing additional elements (CaO–Na 2O–Al 2O 3–Cr 2O 3–TiO 2–FeO–MgO–SiO 2–H 2O). Silica activity was buffered by the presence of either pyroxene (high a
SiO2) or ferropericlase (low a
SiO2), and was buffered by the presence of Ni + NiO or Fe + FeO, or constrained by the presence of Fe 2O 3. Raman spectroscopy was used to identify pyroxene polymorphs in the run products. Clinoenstatite was present in the 1,000°C
experiment, and enstatite in experiments at 1,400–1,520°C. The H 2O content of olivine was measured using secondary ion mass spectroscopy, and infrared spectroscopy was used to investigate
the nature of hydrous defects. The H 2O storage capacity of olivine decreases with increasing temperature at 8 GPa. In contrast to previous experimental results
at ≤2 GPa, no significant effect of varying oxygen fugacity is evident, but H 2O storage capacity is enhanced under conditions of low silica activity. No significant growth of low wavenumber (<3,400 cm −1) peaks, generally associated with high at low pressure, was observed in the FTIR spectra of olivine from the high experiments. Our experiments show that previous high pressure H 2O storage capacity measurements for olivine synthesized under more oxidizing conditions than the Earth’s mantle are not likely
to be compromised by the of the experiments. However, the considerable effect of temperature on H 2O storage capacity in olivine must be taken into account to avoid overestimation of the bulk upper mantle H 2O storage capacity. 相似文献
20.
Two-color photometric data obtained on the 6-m telescope of the Special Astrophysical Observatory are used to analyze the
structure of 13 large disk galaxies in the NGC 80 group. Nine of the 13 studied galaxies are classified as lenticular galaxies.
The stellar populations in the galaxies are very diverse, from old stars with ages of T > 10 billion years (IC 1541) to relatively young stars with ages of T ∼ 1–3 billion years (IC 1548, NGC 85); in one case, star formation is ongoing (UCM 0018+2216). In most of the studied galaxies,
more precisely in all of them brighter than M
B ∼ −18, two-tiered stellar disks are detected, whose radial surface-brightness profiles can be described by two exponential
segments with different characteristic scales—shorter near the center and longer at the periphery. All of the dwarf S0 galaxies
with single-tiered disks are close companions to larger galaxies. Except for this fact, no dependence of the properties of
S0 galaxies on distance from the center of the group is found. Morphological signs of a “minor merger” are found in the lenticular
galaxy NGC 85. Based on these last two results, it is concluded that the most probable mechanism for their transformation
of spiral into lenticular galaxies in groups is gravitational (minor mergers and tidal interactions). 相似文献
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