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31.
A. Gil de Paz J. Zamorano J. Gallego 《Monthly notices of the Royal Astronomical Society》1999,306(4):975-987
We have studied the velocity field of the blue compact dwarf galaxy Mrk 86 (NGC 2537) using data provided by 14 long-slit optical spectra obtained in 10 different orientations and positions. This kinematical information is complemented with narrow-band ([O iii ]5007 Å and H α ) and broad-band ( B , V , Gunn r and K ) imaging. The analysis of the galaxy global velocity field suggests that the ionized gas could be distributed in a rotating inclined disc, with projected central angular velocity of Ω=34 km s−1 kpc−1 . The comparison between the stellar, H i and modelled dark matter density profile indicates that the total mass within its optical radius is dominated by the stellar component. Peculiarities observed in its velocity field can be explained by irregularities in the ionized gas distribution or local motions induced by star formation.
Kinematical evidences for two expanding bubbles, Mrk 86–B and Mrk 86–C, are given. They show expanding velocities of 34 and 17 km s−1 , H α luminosities of 3×1038 and 1.7×1039 erg s−1 , and physical radii of 374 and 120 pc, respectively. The change in the [S ii ]/H α , [N ii ]/H α , [O ii ]/[O iii ] and [O iii ]/H β line ratios with the distance to the bubble precursor suggests a diminution in the ionization parameter and, in the case of Mrk 86–B, an enhancement of the shock-excited gas emission. The optical–near-infrared colours of the bubble precursors are characteristic of low‐metallicity star‐forming regions (∼0.2 Z⊙ ) with burst strengths of about 1 per cent in mass. 相似文献
Kinematical evidences for two expanding bubbles, Mrk 86–B and Mrk 86–C, are given. They show expanding velocities of 34 and 17 km s
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The central Iberian zone of the Hesperian Massif hosts a series of late Hercynian vein-type Sb deposits. One of them is the Mari Rosa mineralization, hosted by metagreywackes and slates of the Schist-Greywacke Complex (Upper Precambrian). The mineralization is characterized by a complex paragenesis comprising three hydrothermal stages: stage H1 arsenopyrite-(pyrite); stage H2 stibnite-gold; and stage H3 pyrite-pyrrhotite-galena-sphalerite-chalcopyrite-tetrahedrite-boul-angerite-stibnite. Of these only the second episode was of importance and gave rise to the main mineralized bodies of the deposit. Hydrothermal alteration consists of a mild sericitization, chloritization and carbonatization of the metasedimentary rocks around the veins. Chemical changes in the hydrothermal halos include a remarkable increase in the ratio K2O/Na2O, and a decrease in the ratio SiO2/volatiles, together with a sharp increase in Sb, Mo, Au and N. Fluids associated with ore deposition lie in the H2O-NaCl-CO2-CH4-N2 compositional system. These fluids evolved, progressively cooling, from initial circulaion temperatures close to 400 °C in the early stage (H1) to temperatures of approximately 150 °C in the late one (H3). Fluid composition evolution was characterized by a progressive increase in the bulk water content of the fluids and with an increase in the relative proportion of N2 with respect to CH4 and CO2 in the volatile fraction. Massive stibnite deposition resulted from a boiling process developed at 300 °C and 0.9–1 Kb at a depth of 4–5 km. Geological, geochemical and fluid inclusion evidence suggest that the intrusion of the Alburquerque batholith (late Hercynian S-type granitoids) triggered hydrothermal activity leading to the transport and deposition of Sb and Au in Mari Rosa. 相似文献
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Ana?Ma?M.?Farrona Fernando?Domínguez-Castro Ma?Cruz?Gallego José?M.?VaqueroEmail author 《山地科学学报》2016,13(6):1047-1055
Antisana is a stratovolcano with an associated glacier located in the Ecuadorian Andes. Dr Aguirre made meteorological readings every day, at every hour from sunrise to sunset, from December 1845 to December 1846, at Antisana using a meteorological station at 4060 mamsl (meters above mean sea level). Unfortunately, only the monthly average data have been preserved. These meteorological data are here studied and compared with the closest modern stations for monthly values of temperature, rainfall, and pressure. According to these comparisons, the year 1846 was rainy and cold in comparison with the current climate. Moreover, these observations have been useful to help resolve a debate about a possible El Niño event in 1846 with the high precipitation in Antisana and Quito in 1846 discarding the occurrence of an El Niño event. The probable occurrence of a La Niña event is discussed. These data are the earliest known systematic instrumental meteorological observations taken at above 4000 mamsl. 相似文献
34.
In this paper we present a measure of the synodic solar rotation rate derived from an analysis of a Flamsteed drawing, corroborating the decrease of the solar rotation in the deep Maunder minimum (1666–1700). 相似文献
35.
We present the sunspot ideas and observations of the 18th century Portuguese scholar Teodoro de Almeida (1722 – 1804) and
Mexican scientist José Antonio Alzate (1737 – 1799). We describe the implications of dating a single sunspot observation performed
by Almeida in the early 1760s, during the maximum of cycle number 1. A possible solar cycle peak in 1760 (instead of 1761)
is investigated. We present several observations of sunspots obtained by Alzate during 1769 (partially associated with the
Venus and Mercury transits) and also on 20 July 1786. We estimate 100±34 as the Group Sunspot Number for this date. These
records were unknown and, therefore, not included in the database compiled by Hoyt and Schatten (1998). 相似文献
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Cindy Mora Diana Comte Ray Russo Alejandro Gallego Victor Mocanu 《Journal of Seismology》2010,14(4):683-691
A seismic swarm at the Aysén fjord started in January, 2007, reaching its highest activity between January and April, 2007. It was punctuated by the Mw5.3 23rd January event and the Mw6.2 21st April event which triggered a water-wave due to massive landslides; both with dextral strike slip focal mechanisms. More than 100 events were relocated with the Joint Hypocenter Determination method to study the depth distribution of the events of the swarm recorded by the Chile Ridge Subduction Project local network. The events are associated to a small area of approximately 7?×?7 km located in the Aysén fjord, on one of the main branches of the Liquiñe–Ofqui fault. Distribution in depth is located between 0 and 8 km and presents a west high dip with almost NS strike, consistent with the main trending of the Liquiñe–Ofqui fault and the published focal mechanisms. These characteristics, among others, suggest that the Liquiñe–Ofqui fault is active in this region and thus seismic risk has to be re-determined. 相似文献
38.
Francisco Javier Acero María Cruz Gallego José Agustín García 《Theoretical and Applied Climatology》2012,108(3-4):411-423
In order to analyze the effects of the duration of precipitation events, trends in extreme rainfall over the Iberian Peninsula (IP) for multi-day extreme precipitation events (1 to 7?days) were evaluated from records of 52 observatories regularly distributed over Iberia with no missing data for the common period 1958–2004. Two approaches were used: first, the nonparametric Mann–Kendall test together with the Sen method, and second, a parametric test based on the statistical theory of extreme values, involving time-dependent parameters to account for possible temporal changes in the frequency distribution. It was found that, in winter, there were significant negative trends for a great part of the Iberian Peninsula, but significant positive trends for the southeast over areas that shrank as the number of days considered for the precipitation event increased. Spring also showed negative trends for a great part of the IP but with a major area of positive trend over the northeast that remained unchanged when considering the maxima of from 1 to 7?days of rainfall. Autumn showed a bipolar spatial pattern, with the west being positive and the east negative. 相似文献
39.
A spectral analysis of Iberian Peninsula monthly rainfall 总被引:2,自引:0,他引:2
J. A. García A. Serrano M. de la Cruz Gallego 《Theoretical and Applied Climatology》2002,71(1-2):77-95
Summary A spectral analysis of Iberian Peninsula monthly rainfall series was carried out. The data set consists of monthly precipitation
records from 40 meteorological observatories over 74 years (1919–1992). The stations are representative of most of the Iberian
Peninsula. The rainfall series were analyzed spatially by means of Principal Component Analysis (PCA) and temporally by means
of the Multi-Taper Method (MTM) of spectral analysis of by Monte-Carlo Singular Spectrum Analysis (MCSSA). The PCA gave six
dominant modes of variation which explain 75% of the variance with each component affecting a different region of the Peninsula.
The spectral analysis showed 7 year oscillations for the dominant pattern and 2.7 and 16 years for the third pattern. The
7-year oscillation seems to be related to other climatic oscillations recorded in the northern hemisphere while the 2.7-year
oscillation could be related to the ENSO phenomenon.
Received July 18, 2000 Revised April 19, 2001 相似文献
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