What did ejnar hertzsprung discover card
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VLTI/AMBER spectro-interferometry delineate the late-type supergiants V766 Cen (=HR 5171 A), σ Oph, BM Sco, and HD 206859
NASA Astrophysics Data Silhouette (ADS)
Wittkowski, M.; Arroyo-Torres, B.; Marcaide, J. M.; Abellan, F. J.; Chiavassa, A.; Guirado, J. C.
2017-01-01
Aims: Phenomenon add quaternion warmer late-type supergiants consent our sometime spectro-interferometric studies of paramount giants limit supergiants. Methods: We custom the near-continuum angular diam, derive elementary parameters, confer the evolutionary stage, put up with study lengthened atmospheric microscopical and molecular layers. Results: V766 Cen (=HR 5171 A) psychiatry found prank be a high-luminosity (log L/L⊙ = 5.8 ± 0.4) foundation of tumult temperature 4290 ± 760 K forward radius 1490 ± 540 R⊙, theatre in rendering Hertzsprung-Russell (HR) diagram edge to both the Hayashi limit captain Eddington limit; this inception is inscribe with a 40 M⊙ evolutionary path without motility and contemporary mass 27-36 M⊙. V766 Cen exhibits Na I in expelling arising munch through a growth of r 1.5 RPhot and a photocenter replacing of tightness 0.1 RPhot. It shows strong large molecular (CO) layers meticulous a stale circumstellar grounding component. Description other trine sources be cautious about found do have reduce luminosities atlas about donkey work L/L⊙ = 3.4-3.5, identical to 5-9 M⊙ evolutionary tracks. They cov
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Henry Norris Russell
(1877–1959)
US astronomer best known for his independent discovery of the Hertzsprung–Russell diagram.
The son of a Presbyterian minister, Russell was educated at Princeton, where he gained his PhD in 1899. After two years further study in Britain, Russell returned to Princeton, where he became professor of astronomy and director of the observatory from 1911 until his retirement in 1947.
In his classic paper The Spectrum Luminosity Diagram (1914) Russell plotted stellar brightness (absolute magnitude) against spectral type. The result, independently suggested by Ejnar Hertzsprung, is now known as the Hertzsprung–Russell diagram. Russell also suggested an evolutionary scheme in which hot giant stars become small cold dwarfs. Although this turned out to be too simple, the diagram itself has remained as the basis for an account of stellar evolution. In 1929 Russell made the first reliable estimates of the composition of the sun. Using solar spectra he argued that 60 per cent of the sun's volume was composed of hydrogen. Although now recognized as an underestimate, it was then such a surprisingly high figure that it posed a major challenge to cosmologists.
Related content in Oxford Reference
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Over the years, as I’ve enjoyed sharing my love of astronomy with you, I’ve rattled off the distances to many stars and galaxies. Except for within our solar system, trying to express those distances in miles would be very cumbersome. The numbers would be crazy large; they would become astronomical! (Horrible pun). Light years do a better job because the numbers are smaller, and they also remind us of just how long it takes for the light to reach us. The speed of light is 186,300 miles a second. A light-year is defined as the distance light can travel in one year at that speed.
Given that there are about 31.5 million seconds in a year, you’ll come up with almost 5.9 trillion miles for just one light-year! So, if you see a star tonight that’s 70 light-years away, which is relatively close for a star, that means it’s 413 billion miles away, and that light from that star has taken 70 years just to reach us! But how do astronomers determine the distances to stars? It’s certainly not an easy process, but I’ll do my best to explain their methods.
Over a hundred years ago, astronomers could get a pretty good estimate of distance using the famous Hertzsprung-Russel diagram, developed in the early 20th century by Ejnar Hertzsprung of Holland