排序方式： 共有65条查询结果，搜索用时 31 毫秒
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A. C. Becker E. Agol N. M. Silvestri J. J. Bochanski C. Laws A. A. West G. Basri V. Belokurov D. M. Bramich J. M. Carpenter P. Challis K. R. Covey R. M. Cutri N. W. Evans M. Fellhauer A. Garg G. Gilmore P. Hewett P. Plavchan D. P. Schneider C. L. Slesnick S. Vidrih L. M. Walkowicz D. B. Zucker 《Monthly notices of the Royal Astronomical Society》2008,386(1):416-424
We report on Two-Micron All-Sky Survey (2MASS) J01542930+0053266, a faint eclipsing system composed of two M dwarfs. The variability of this system was originally discovered during a pilot study of the 2MASS Calibration Point Source Working Data base. Additional photometry from the Sloan Digital Sky Survey yields an eight-passband light curve from which we derive an orbital period of 2.639 0157 ± 0.000 0016 d. Spectroscopic followup confirms our photometric classification of the system, which is likely composed of M0 and M1 dwarfs. Radial velocity measurements allow us to derive the masses (M1 = 0.66 ± 0.03 M⊙ ; M2 = 0.62 ± 0.03 M⊙ ) and radii (R1 = 0.64 ± 0.08 R⊙ ; R2 = 0.61 ± 0.09 R⊙ ) of the components, which are consistent with empirical mass–radius relationships for low-mass stars in binary systems. We perform Monte Carlo simulations of the light curves which allow us to uncover complicated degeneracies between the system parameters. Both stars show evidence of Hα emission, something not common in early-type M dwarfs. This suggests that binarity may influence the magnetic activity properties of low-mass stars; activity in the binary may persist long after the dynamos in their isolated counterparts have decayed, yielding a new potential foreground of flaring activity for next generation variability surveys. 相似文献
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Alexander Kurnosov Hauke Marquardt Leonid Dubrovinsky Vasily Potapkin 《Comptes Rendus Geoscience》2019,351(2-3):280-285
Fiber-based laser heating systems offer high flexibility and are increasingly used in high-pressure/high-temperature research. Previous fiber-based laser heating systems were based on lasers delivering radiation with 1-μm wavelength that show unfavorable heating characteristics for many sample materials. We report on the development and first experiments of a waveguide (fiber)-based CO2-laser heating system that can be used in a flexible manner for high-temperature research and for high-pressure/temperature experiments when combined with diamond-anvil cells. The waveguide-based CO2-laser heating system allows convenient heating of optically transparent samples without the need for adding an additional laser absorber. In a pilot experiment, the flexible heating system has been installed on a Brillouin scattering system to measure high-temperature sound-wave velocities in single-crystal MgO. The waveguide-based CO2-laser heating system offers perspectives for a variety of scientific applications, most importantly those that require the use of synchrotron facilities where space is limited and flexible solutions are required. 相似文献
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Naki Akçar Susan Ivy-Ochs Vasily Alfimov Anne Claude Hans R. Graf Andreas Dehnert Peter W. Kubik Meinert Rahn Joachim Kuhlemann Christian Schlüchter 《Swiss Journal of Geoscience》2014,107(2-3):337-347
The Swiss Deckenschotter (“cover gravels”) is the oldest Quaternary units in the northern Swiss Alpine Foreland. They are a succession of glaciofluvial gravel layers intercalated with glacial and/or overbank deposits. This lithostratigraphic sequence is called Deckenschotter because it “covers” Molasse or Mesozoic bedrock and forms mesa-type hill-tops. Deckenschotter occurs both within and beyond the extent of the Last Glacial Maximum glaciers. The Swiss Deckenschotter consist of two sub-units: Höhere (Higher) and Tiefere (Lower) Deckenschotter. Although the Höhere Deckenschotter sub-unit (HDS) is topographically higher than the Tiefere Deckenschotter, it is older. The only available age for the Swiss Deckenschotter is 2.5–1.8 Ma based on mammal remains found in HDS at the Irchel site. In this study, we present an exposure age for the topographically lowest HDS, calculated from a cosmogenic 10Be depth-profile. Our results show that the first phase of the Deckenschotter glaciations in the Swiss Alps terminated at least 1,020\(_{ - 120}^{ + 80}\) ka ago, which is indicated by a significant fluvial incision. This line of evidence seems to be close to synchronous with the beginning of the Mid-Pleistocene Revolution, when the frequency of the glacial-interglacial cyclicity changed from 41 to 100 ka and the amplitude from low to high, between marine isotope stages 23 and 22. 相似文献
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Donald B. Percival Donald W. Denbo Marie C. Eblé Edison Gica Harold O. Mofjeld Michael C. Spillane Liujuan Tang Vasily V. Titov 《Natural Hazards》2011,58(1):567-590
The ability to accurately forecast potential hazards posed to coastal communities by tsunamis generated seismically in both
the near and far field requires knowledge of so-called source coefficients, from which the strength of a tsunami can be deduced.
Seismic information alone can be used to set the source coefficients, but the values so derived reflect the dynamics of movement
at or below the seabed and hence might not accurately describe how this motion is manifested in the overlaying water column.
We describe here a method for refining source coefficient estimates based on seismic information by making use of data from
Deep-ocean Assessment and Reporting of Tsunamis (DART
\circledR^{\circledR}) buoys (tsunameters). The method involves using these data to adjust precomputed models via an inversion algorithm so that
residuals between the adjusted models and the DART
\circledR^{\circledR} data are as small as possible in a least squares sense. The inversion algorithm is statistically based and hence has the
ability to assess uncertainty in the estimated source coefficients. We describe this inversion algorithm in detail and apply
it to the November 2006 Kuril Islands event as a case study. 相似文献
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GAIA is the 'super- Hipparcos ' satellite scheduled for launch in 2010 by the European Space Agency. It is a scanning satellite that carries out multi-colour, multi-epoch photometry on all objects brighter than 20th mag. We conduct detailed simulations of supernovae (SNe) detection by GAIA . Supernovae of each type are chosen according to the observed distributions of absolute magnitudes, and located in nearby galaxies according to the local large-scale structure. Using an extinction model of the Galaxy and the scanning law of the GAIA satellite, we calculate how many SNe are detectable as a function of the phase of the light curve. Our study shows that GAIA will report data on ∼21 400 SNe during the five-year mission lifetime, of which ∼14 300 are SNe Ia, ∼1400 are SNe Ib/c and ∼5700 are SNe II. Using the simulations, we estimate that the numbers caught before maximum are ∼6300 SNe Ia, ∼500 SNe Ib/c and ∼1700 SNe II. During the mission lifetime, GAIA will issue about 5 SNe alerts a day.
The most distant SNe accessible to GAIA are at a redshift z ∼ 0.14 and so GAIA will provide a huge sample of local SNe. There will be many examples of the rarer subluminous events, over-luminous events, SNe Ib/c and SNe II-L. SNe rates will be found as a function of galaxy type, as well as extinction and position in the host galaxy. Amongst other applications, there may be about 26 SNe each year for which detection of gravitational waves is possible and about 180 SNe each year for which detection of gamma-rays is possible. GAIA 's astrometry will provide the SN position to better than milliarcseconds, offering opportunities for the identification of progenitors in nearby galaxies and for studying the spatial distribution of SNe of different types in galaxies. 相似文献
The most distant SNe accessible to GAIA are at a redshift z ∼ 0.14 and so GAIA will provide a huge sample of local SNe. There will be many examples of the rarer subluminous events, over-luminous events, SNe Ib/c and SNe II-L. SNe rates will be found as a function of galaxy type, as well as extinction and position in the host galaxy. Amongst other applications, there may be about 26 SNe each year for which detection of gravitational waves is possible and about 180 SNe each year for which detection of gamma-rays is possible. GAIA 's astrometry will provide the SN position to better than milliarcseconds, offering opportunities for the identification of progenitors in nearby galaxies and for studying the spatial distribution of SNe of different types in galaxies. 相似文献
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Jose C. Borrero Brian McAdoo Bruce Jaffe Lori Dengler Guy Gelfenbaum Bretwood Higman Rahman Hidayat Andrew Moore Widjo Kongko Lukijanto Robert Peters Gegar Prasetya Vasily Titov Eko Yulianto 《Pure and Applied Geophysics》2011,168(6-7):1075-1088
On the evening of March 28, 2005 at 11:09?p.m. local time (16:09 UTC), a large earthquake occurred offshore of West Sumatra, Indonesia. With a moment magnitude (M w) of 8.6, the event caused substantial shaking damage and land level changes between Simeulue Island in the north and the Batu Islands in the south. The earthquake also generated a tsunami, which was observed throughout the source region as well as on distant tide gauges. While the tsunami was not as extreme as the tsunami of December 26th, 2004, it did cause significant flooding and damage at some locations. The spatial and temporal proximity of the two events led to a unique set of observational data from the earthquake and tsunami as well as insights relevant to tsunami hazard planning and education efforts. 相似文献
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