Astronomy 15.4
During a solar eclipse observed in 1919, the sky turned dark as the Moon moved in front of the Sun. Stars were visible in daylight. At this time, a few stars that were in the same part of the sky as the Sun looked like they were shifted temporarily to the side of their known true positions (coordinates). What did this help confirm?
Any large mass causes warped spacetime in its nearby environment.
Astronomers believe that the many supernova explosions that have happened in the Milky Way Galaxy could have played a role in the evolution of life over billions of years. What would have been their role?
Least massive: white dwarf. Most massive: black hole.
Sometimes a dead white dwarf star is part of a binary star system, where it orbits with an old giant star. If the giant star is close to it, gas is pulled from the giant onto the dead star due to the dead star's strong gravity. This can lead to either a Type Ia supernova explosion or a milder nova explosion. What factor strongly determines which kind of explosion occurs? Answer: The ________ of the white dwarf when the explosion is about to happen. Group of answer choices
Mass
When one member of a binary star system is a black hole, and astronomers detect flickering X-rays coming from the system, where are these X-rays usually coming from?
Material that came over from a companion star and is swirling in a disk around the black hole
What is true about the event horizon of a black hole
Nothing inside that limit can ever come out, not even light.
What incident in a massive star's life sets off (begins) the very quick chain of events that leads to a supernova explosion?
Nuclear fusion has begun making iron.
A neutron star is a highly compressed ball of neutrons, about 10-15 miles wide, that is left after certain supernova explosions. If it is spinning fast and flashing a beam periodically in our direction, then we see pulses of light coming from it (mostly radio wave light). Then we can call it a pulsar. What factor strongly focuses particles into two beams that glow outward from the pulsar?
Strong Magnetism
In 1959, Pound and Rebka did an experiment to test the prediction of Einstein's theory of general relativity about the relationship between the pace of time and the strength of gravity. When two identical atomic clocks, one on the ground floor and one on the top floor, were compared, what did they discover?
The clock on the ground floor ran a tiny bit slower.
If the core of a massive star becomes a neutron star, what happens to the rest of the star's layers? Group of answer choices
The layers explode outward as a supernova.
In the first direct detection of gravitational waves by LIGO in 2015, the waves came from what source?
The merger of two black holes
When a star undergoes a nova explosion, it may return to its "quiet state" and later become a nova again. What would allow a nova explosion to happen to a star more than once like that? Group of answer choices
The star that goes nova has a companion star near it that resumes feeding it after the nova.
Astronomers believe that the many supernova explosions that have happened in the Milky Way Galaxy could have played a role in the evolution of life over billions of years. What would have been their role?
They produced cosmic rays which would have contributed to the rate of mutations over many generations.
The Chandrasekhar Limit is a limit on the maximum mass that a certain kind of dead star is allowed to have. What is this type of dead star
White Dwarf
Astronomers have long realized that supernovae - when they explode - give off an enormous amount of light. But observations of Supernova 1987A (in the Large Magellanic Cloud) revealed that the supernova gives off even more energy in the form of ________.
neutrinos
Once a black hole forms, the size of its event horizon is determined only by ________.
the mass inside the event horizon
According to Einstein's general theory of relativity, the stronger a star's gravity, _______.
the slower time runs near it
