Astronomers use the term "luminosity" to refer to the total amount of energy emitted by a celestial body per unit time. The red line in the diagram represents the threshold luminosity for the 4U ...
Using ESA's XMM-Newton satellite, astronomers from Stanford University and elsewhere have conducted deep X-ray observations ...
A glance at the night sky above Earth shows that some stars are much brighter than others. However, the brightness of a star depends on its composition and how far it is from the planet. Astronomers ...
Over the 25 years I’ve written this column, I’ve often marveled at the mind-boggling distances to many celestial objects. Astronomers don’t often use miles to express stellar and galactic distances ...
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How did Edwin Hubble prove Andromeda was a galaxy?
How did a Cepheid variable star help Edwin Hubble prove the Andromeda Nebula was a galaxy? Roger Brady San Quentin, California Cepheids are rare variable stars with periods ranging from about 1 to 120 ...
The birth of massive stars is still a mystery to us. This is because these stars are embedded in an extremely dense medium of gas and dust, says Rolf Kuiper, the leader of the Emmy Noether Research ...
Over the 25 years I’ve written this column, I’ve often marveled at the mind-boggling distances to many celestial objects. Astronomers don’t often use miles to express stellar and galactic distances ...
When we look up at the night sky, we see a glittering carpet of stars. These twinkling pinpricks of light are actually massive balls of plasma—super-heated helium and hydrogen gas. They are powered by ...
Cepheid stars have predictable brightness changes linked to their periods. This period-brightness relationship lets astronomers calculate a Cepheid's distance. Hubble found a Cepheid in the Andromeda ...
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