Descriptive Astronomy Chapters 12,13,14

Without the fusion of Hydrogen into helium in the core, the core no longer an energy source. Gravity is able to collapse the core, forcing major changes in the entire structure of the star.

A planetary nebula is the ejected shell of an evolved giant star. It is the shape of a spherical shell and is composed of relatively cool thing gas, which was once the outer part of the star. A planetary nebula is associated with the death of a low mass star.

The type I supernova are observed to have hydrogen poor spectra and are fainter than type II supernova. There is a difference in the shape of the light curve in that type II will sustain its luminosity level over a longer period of time than a type I before it begins to fade.

In a type II supernova, the core is surrounded by Hydrogen and Helium rich layer. The type I virtually contains no Hydrogen or Helium, so the spectrum is very weak in those elements. The light curve of the type I supernova is almost toally due to radioactive decay of elements, whereas the type II supernova has a light curve indicative of an expanding cloud of gas, blown up into space by the shockwave.

TRUE In a core collapse supernova the inward force due to gravity will begin to compress the star with the core being compressed to a neutron core until it can't sustain the compression any longer and begins to react or rebound by generating a shock wave which casues the supernova explosion.

FALSE Because of stellar nucleosynthesis the older stars will supply the heavier elements when they explore into supernovas. As such when the younger stars are formed they will contain the heavier elements as part of their matter structure.

White Dwarf

In mass-transfer binary star systems, something other than mass is transferred to the neutron star; angular momentum can be transferred also. This results in making the neutron star spin faster and faster. The angular momentum is taken from the orbital motion of the two stars.

Before entering the black hole, tidal forces would pull a person apart. Gravity is so strong near the black hole that the difference in the force on the two sides of the person is sufficient to tear him or her apart. This would be true of any type of matter that got close to the black hole.

FALSE Gravity is so strong that it can attact even light, as proposed by Einstein in the General Theory of Relativity.

A neutron star will shrink to about the size of a U.S city after type II supernova core collapse.

in the radio part of the spectrum, atomic Hydrogen gas emits 21-cm radiation. Because its long wavelength allows it to travel through the galaxy without absorbtion by dust, astronomers can use it to map the structure of gas clouds in the sky. Radio sources are more useful than observations made by visible light becuse the radio waves penetrate the dust that obscures the visible wavelengths.

Different parts of the galaxy rotate at different rates. The rotation is actually the motion of the stars and gas around the galaxy. Because the Milky way is not a solid body, like Earth, different parts of it move at different rates. The orbital motions are determined strictly by the amount of mass interior to the orbit.

False, molecular hydrogen clouds unlike the hydrogen element does not emit a or absorb 21-cm radiation. 21cm is sensitive to atomic hydrogen, but not to the molecular from the hydrogen gas. Instead astronomer use radio observation of the other molecules such as carbon monoxide (CO), hydrogen cyanide (HCN), and other to study the dark interiors of the dusty regions.

within a spiral arm, new formed stars can be found in the spiral arms of a galaxy. These arms go through a period called density waves in which the arms get compressed and decompressed. It is during the compression that the opportunity exists for stars to form.