What are spectral lines in astronomy? A spectral line is like a fingerprint that can be used to identify the atoms, elements or molecules present in a star, galaxy or cloud of interstellar gas. If we separate the incoming light from...
What is the singularity in a black hole? The singularity at the center of a black hole is the ultimate no man’s land: a place where matter is compressed down to an infinitely tiny point, and all conceptions of time and...
Where do X-rays come from in black holes? X-rays are emitted from a corona of energetic particles close to the black hole. Some of these rays reach the observer directly, but some illuminate the inner regions of the accretion disk and...
How does a black hole is formed? Stellar black holes form when the center of a very massive star collapses in upon itself. This collapse also causes a supernova, or an exploding star, that blasts part of the star into space....
What is the temperature of a white dwarf? Near the end of its nuclear burning stage, this type of star expels most of its outer material, creating a planetary nebula. Only the hot core of the star remains. This core becomes...
How hot is a white dwarf in K? Most observed white dwarfs have relatively high surface temperatures, between 8,000 K and 40,000 K. How hot is the hottest white dwarf? Astronomers at the Universities of Tübingen and Potsdam have identified the...
Are black dwarfs hot? The ultimate stage of stellar evolution for many stars is a black dwarf. Because they emit no heat or light, these objects would be a challenge to detect if they existed today. What happens when a black...
Is a brown dwarf a failed star? Brown dwarfs are failed stars about the size of Jupiter, with a much larger mass but not quite large enough to become stars. Like the sun and Jupiter, they are composed mainly of hydrogen...
How old is the oldest white dwarf? Extremes Title Star Data Nearest Sirius 8.6 ly (2.6 pc) Farthest SN UDS10Wil progenitor 10,000,000,000Ly z=1.914 Oldest WD 0343+247 SDSS J110217.48+411315.4 12 Gy (tied) Youngest SDSS J0003+0718 < 13 My What is the lifespan...
What are the dwarf stars? A dwarf star is a star of relatively small size and low luminosity. Most main sequence stars are dwarf stars. The meaning of the word “dwarf” was later extended to some star-sized objects that are not...