Results 171 to 180 of about 462 (193)

INDIGENOUS ORGANIC MATTER ON THE MOON. [PDF]

Proc Natl Acad Sci U S A, 1960
Sagan C.
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Stellar evolution I - Calibration of the Hertzsprung-Russell diagram in terms of age and mass for main-sequence B and A stars

, 1966
T. Kelsall, Bengt Stroemgren
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The dramatic transition of the extreme Red Supergiant WOH G64 to a Yellow Hypergiant

Munoz-Sanchez G, Kalitsounaki M, de Wit S, Antoniadis K, Bonanos A, Zapartas E, Boutsia K, Christodoulou E, Maravelias G, Soszyński I, Udalski A.   +10 more
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Impersonal parameters from Hertzsprung-Russell diagrams

Monthly Notices of the Royal Astronomical Society, 2003
An objective process for estimation of star cluster parameters from Hertzsprung-Russell (HR) diagrams is introduced, with direct inclusion of multiple stars, a least-squares fitting criterion, and standard error estimates. No role is played by conventional isochrones. Instead the quantity compared between observation and theory is the density of points
Wilson, Robert E., Hurley, Jarrod R.
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The Hertzsprung-Russell diagram

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 1961
The theory of stellar evolution aims at predicting the luminosity L and radius R of a star as a function of its mass M , its initial composition, and its age. As the time scales are so long, comparison with observation must necessarily be indirect.
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The Hertzsprung-Russell Diagram

2014
We have already covered many topics in our description of a star’s basic characteristics, such as its mass, radius, spectral type and temperature. We can now put all of these parameters together to form a picture of how a star evolves. This is often quite useful in many sciences to represent the characteristics, or data, about a group of objects in the
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The Hertzsprung-Russell Diagram

1958
Two of the fundamental quantities which describe a star are luminosity and temperature. A Hertzsprung-Russell diagram (H-R diagram) is a graphical representation of a group of stars which uses as coordinates their absolute magnitudes and spectral types. Spectral type is principally a temperature classification.
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Steps toward the Hertzsprung–Russell Diagram

Physics Today, 1978
In the late nineteenth century, astronomers seeking to classify stars by their spectra using then-current concepts of stellar evolution found a temperature–luminosity plot that revolutionized the subject.
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Magnetic Activity Across the Hertzsprung-Russell Diagram

1991
Emissions from the outer atmospheres of cool stars are discussed using flux-color, flux-flux, and flux-rotation diagrams. Two distinct components have been identified: a basal emission and a magnetically controlled emission (“magnetic activity”). The tight power-law relations between the flux densities point to one single activity parameter determining
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The Upper Boundaries of the Hertzsprung-Russell Diagram

1980
Why is it that there are no stars brighter than (roughly) a few million times the Sun, hotter than approximately a hundred-thousand degrees, or cooler than a few thousand degrees?
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