14. Stars 1

Transcript: A parsec is a distance unit appropriate to the study of stars. It’s the distance that produces a parallax s... Read more

Transcript: Apparent brightness does not express a star or other source of light’s true energy output. Astronomers are ... Read more

Transcript: The vast distances to the nearest stars encourage astronomers to use a new unit of distance. Whereas meters... Read more

Transcript: Nearly 2,000 years ago Ptolemy's Almagest, a compendium of astronomical information, contained catalogs of s... Read more

Transcript: Almost all of the world’s energy comes from non-renewable sources or fossil fuels. These energy sources too... Read more

Transcript: The H-R diagram is a plot of spectral class, or equivalently effective temperature, against stellar luminosi... Read more

Transcript: As a way of exploring stellar properties and understanding how stars work, in the early twentieth century tw... Read more

Transcript: A human lifetime is a blink of an eye compared to the age of the stars which can be hundreds of millions or ... Read more

Transcript: Most stars are very different in chemical composition from you, or I, or the material on the Earth. The Sun... Read more

Transcript: The way astronomers observe and calibrate the apparent brightness of something is through the technique of p... Read more

Transcript: The first direct estimate of stellar distances used geometry. In 1838, Friedrich Bessel measured the parall... Read more

Transcript: The magnitude scale is defined in such a way as a magnitude difference of five magnitudes corresponds to a f... Read more

Transcript: Apparent magnitude or apparent brightness must be specified at a particular wavelength. Stars have differen... Read more

Transcript: We can use relative brightness to show how bright various objects in the night sky are compared to the limit... Read more

Transcript: The apparent brightness of the Sun is a factor of 1010 or 10 billion times brighter than the brightest stars... Read more

Transcript: Since light has a finite speed, three hundred thousand kilometers per second, there’s an inevitable conseque... Read more

Transcript: Some stars in the sky, somewhat hotter than the Sun with temperatures of 5 thousand to 10 thousand Kelvin, h... Read more

Transcript: Certain rare stars in the sky with either red or blue colors are extremely luminous, up to a million times t... Read more

Transcript: A cool main sequence star with a temperature of about three thousand Kelvin lies on the main sequence with a... Read more

Transcript: As was first seen nearly a hundred years ago, when luminosities and effective temperatures are gathered for ... Read more