排序方式： 共有6条查询结果，搜索用时 15 毫秒
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The interstellar reddening law in the Taurus dark clouds is investigated from visual, infrared, and ground based ultraviolet photometric observations of heavily reddened stars HD 29647, HDE 283701, and HDE 283812. The star HD 29647 located in the center of a very dense dark cloud Khavtassi 278 shows a reddening law which is anomalous in the wavelengths shorter than 400 nm. When combined with observations by Snow and Seab from the IUE it can be represented by a single straight line from 1 m to 250 nm. Other two stars situated in less dense parts of the Taurus dark clouds show normal reddening law. 相似文献
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A. F. Kowalski S. L. Hawley J. A. Holtzman J. P. Wisniewski E. J. Hilton 《Solar physics》2012,277(1):21-29
The white light during M dwarf flares has long been known to exhibit the broadband shape of a T≈10 000 K blackbody, and the white light in solar-flares is thought to arise primarily from hydrogen recombination. Yet, a
current lack of broad-wavelength coverage solar flare spectra in the optical/near-UV region prohibits a direct comparison
of the continuum properties to determine if they are indeed so different. New spectroscopic observations of a secondary flare
during the decay of a megaflare on the dM4.5e star YZ CMi have revealed multiple components in the white-light continuum of
stellar flares, including both a blackbody-like spectrum and a hydrogen-recombination spectrum. One of the most surprising
findings is that these two components are anti-correlated in their temporal evolution. We combine initial phenomenological
modeling of the continuum components with spectra from radiative hydrodynamic models to show that continuum veiling causes
the measured anti-correlation. This modeling allows us to use the components’ inferred properties to predict how a similar
spatially resolved, multiple-component, white-light continuum might appear using analogies to several solar-flare phenomena.
We also compare the properties of the optical stellar flare white light to Ellerman bombs on the Sun. 相似文献
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Wieslaw Z. Wisniewski 《Icarus》1976,28(1):87-90
Spectrophotometric and broad-band photoelectric observations of Eros are reported. No existing meteorite spectrum matches the asteroid data directly. Assemblages of iron or stony-iron with ordinary-chondrite material generate the best match for the reflectivity curve of Eros. Variability was found in the 0.6 micron band and V-R and V-I colors. 相似文献
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Five narrowband interference filters centered at wavelengths 0.365, 0.387, 0.406, 0.484, and 0.514 μm have been selected by the International Astronomical Union to represent ultraviolet continuum, CN emission, C3 emission, blue continuum, and C2 emission in the spectra of comets, respectively. We present adopted magnitudes and colors in this filter system for 50 standard stars ranging in blue magnitude 4 to 12, in spectral type from O to K, and mostly distributed around equatorial regions of the sky. Tabulated uncertainties are generally on the order of 0.02 mag or smaller. The zero points of the photometric system are chosen such that blue-continuum magnitudes are approximately equivalent to Johnson B, and such that color indices average zero for solar analog stars. 相似文献
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