Astronomy Exam 3 HW

According to the general theory of relativity, the presence of mass A. causes a curvature (or warping) of spacetime B. will cause a black hole to form unless there is a motion C. is equivalent to the presence of light D. causes curved paths to straighten out until they are exactly straight lines E. causes motion at the speed of light squared

A

If you are in a freely falling elevator near the top of a tall building, as the elevator falls, your weight would be: A. equal to zero - you would be weightless B. a little more than your usual weight C. so great that you would be pressed to the floor and in great pain D. the same as your usual weight E. a bit less than your usual weight

A

Our Milky Way Galaxy is what type of galaxy? A. spiral B. elliptical C. None of these D. elliptical E. irregular

A

An astronomer needs to measure the distance to a globular cluster of stars that is part of a neighboring galaxy nearby the Milky Way Galaxy. What method should she try to use to find the distance? A. count the number of O and B type stars in the cluster B. find a variable star (cepheid or RR Lyrae) in the cluster C. measure the red-shift of the cluster D. look for flickering x-rays coming from a black hole in a binary star system in the cluster E. measure the parallax of the cluster

B

To predict whether a star will ultimately become a black hole, what is the key property of the star we should look at? A. color B. distance C. mass D. diameter E. surface temperature

C

When Einstein proposed his General Theory of Relativity, he suggested some pretty strange ideas about space, time, and gravity. How did scientists in 1919 show that Einstein's theory described the behavior of the real world and wasn't just a crazy hypothesis? A. by finding x-rays from a black hole B. by using an H-R diagram for a nearby cluster of stars C. by observing starlight coming close to the Sun during an eclipse D. by dropping different weights from very tall buildings E. by discovering the process of nuclear fusion

C

Astronomers have concluded that growing supermassive black holes (which have millions of times the Sun's mass or more) is pretty unlikely at our location in the Milky Way Galaxy. Where do they think is the most likely place in the Milky Way for such a supermassive black hole? A. no place in our Galaxy is likely for a really massive black hole B. at the location astronomers call Cygnus X-1 C. where a neutron star has already formed D. at the center of the Milky Way Galaxy, where the matter is more crowded E. at the outer edge of the Galaxy's disk, where there is less pull from other stars

D

In the far future, a starship becomes trapped inside the event horizon of a black hole. Although the crew discovers that their ship cannot out, they at least want to send a message to other ships in the area to stay away from the danger zone. If they send out a message in the form of a radio wave, what will be its fate? A. the message will never emerge from the event horizon the radio wave will become a gamma-ray by the time it emerges from the event horizon B. the radio wave will only emerge from the event horizon if it is moving in the direction of the magnetic north and south pole of the star that formed the black hole C. the message will emerge from the event horizon with a huge gravitational redshift D. although the radio wave will emerge from the event horizon, all the information in the message will be garbled

A

William Herschel thought that the Sun and Earth were roughly at the center of the great grouping of stars we call the Milky Way. Today we know this is not the case. What was a key reason that Herschel did not realize our true position in the Milky Way? A. the dust that extends throughout the disk of the Galaxy only allowed Herschel to see the small part of the Milky Way that B. his telescope was only able to show him objects inside the solar system, and not objects in the Galaxy C. there are so many black holes in the Galaxy, that they absorb a substantial part of the light from distant objects; we needed x-ray astronomy to see to more distant regions D. Herschel shared with ancient people the firm religious belief that we must be the center of everything E. he did not have a telescope, and most stars are too far away to see without a telescope

A

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? A. from the singularity B. from a disk of material around the black hole (material that has been pulled from the companion star and is falling toward the black hole) C. from inside the black hole event horizon D. from the photosphere of the companion star (the star that is not a black hole) E. from a distant galaxy that just happens to lie behind the black hole system (astronomers discovered that such x-rays have nothing to do with the black hole)

B

Astronomers now know that surrounding the main body of our Galaxy (which our various kinds of telescopes have shown to us) and our fainter halo of stars there is A. a pair of long, bright jets of materials produced by a massive black hole and its accretion disk B. a set of huge clouds with many interesting molecules (like alcohol, carbon monoxide, and ammonia) in them C. an invisible halo made of what astronomers are calling "dark matter" D. only the empty space that lies between galaxies E. a series of hundreds and hundreds of nearby small galaxies, held in place by the Milky Way's gravity

C

In the first direct detection of gravitational waves by LIGO in 2015, the waves came from A. a supernova explosion in a nearby galaxy B. the collapse of a nearby star into a white dwarf C. a case of mistaken identity when a big truck drove by D. the merger of two black holes E. the rapid motion of three hot Jupiter planets around a nearby star

D

The first time that astronomers observed both gravitational waves and electromagnetic waves from the same event, what they were observing was: A. a binary star system where a giant star is overloading a white dwarf with too much material B. the merger of two black holes with masses dozens of times the mass of our Sun C. a supernova explosion in one of the closest galaxies to us D. the spiraling toward each other of two neutron stars E. the collapse of an entire cluster of stars into one big black hole

D

What type of main-sequence star is most likely to become a black hole? A. all spectral types on the main sequence have an equal chance of becoming black holes B. an M-type star C. a K-type star D. a G-type star E. an O-type star

E