ASTR 123 Midterm Review

Ace your homework & exams now with Quizwiz!

what is true about the life of a star with a mass like the sun

as the star is dying, a considerable part of its mass will be lost into space

Astronomers identify the main sequence on the H-R diagram with what activity in the course of a star's life?

fusing hydrogen into helium in their cores

The most common element in the sun is

hydrogen

the most stable (tightly bound) atomic nucleus in the universe is

iron

As astronomers have learned more about the structure of the sun, they have found that it

is made entirely of hot gas

Measurements show a certain star has a very high luminosity (100,000 x the Sun's) while its temperature is quite cool (3500°K) How can this be?

it must be quite large in size

today we realize that the source of energy for the sun is a process called

nuclear fusion

the process of fusion that keeps our sun shining begins with which building blocks

two protons

When a single star with a mass equal to the sun dies, it will become a

white dwarf

In the p-p process 4H→__+2e⁺+2y+2v the missing product is

a helium nucleus

at the end of the p-p chain of nuclear fusion in the sun, hydrogen nuclei have been converted into

a helium nucleus

according to the formula E=mc²

a little bit of mass can be converted into a substantial amount of energy

which of the following, produced at the core of the sun, will take the shortest time to emerge from the sun's photosphere (surface)?

a neutrino

when the mass of a star's core is greater than 1.4 times the mass of the sun, degenerate electrons can't keep it stable as a white dwarf instead it becomes

a neutron star

Astronomers now think that there is a black hole with more than 4 million times the mass of our sun at the center of our galaxy. Roughly how large would the event horizon of such a supermassive black hole be?

about 17 times the size of the sun

The event in the life of a star that begins its expansion into a giant is

almost all the hydrogen in its core that was hot enough for the fusion has been turned into helium

the nucleus of the hydrogen atom

has a positive electric charge, is an ingredient in the fusion process in the sun, and is a proton

which of the following statements about the different types (shapes) of galaxies is correct

collisions and mergers between galaxies can sometimes change a galaxies type (shape)

you are alone in a large, completely dark auditorium on Earth. What kind of telescope should I use from the other side of the auditorium to detect the electromagnetic radiation emitted by your body

infrared

what happens to the positron created during the p-p chain of nuclear reactions inside the sun

it quickly collides with an electron and turns into gamma-ray energy

How long a main sequence star remains on the main sequence in the H-R diagram depends most strongly on

its mass

when a large nucleus breaks apart (or is broken apart) into two smaller pieces, this is called

nuclear fission

Where on the H-R Diagram would we find stars that look red when seen through a telescope

only on the right side of the diagram and never on the left

the sun is composed of matter in the form of a

plasma

the antimatter version of an electron is called

positron

which of the following has the longest wavelengths

radio waves

compared at the mass of our own Milky Way galaxy, the total mass we estimate for the Andromeda galaxy is

somewhat bigger

what stages will our own sun go through in the future

spending a long time on the main sequence, expanding to become red giant, eventually fusing helium into carbon, giving off a planetary nebula

our Milky Way galaxy is what type of galaxy

spiral

the type of galaxy that sometimes has a distinct bar of stars running across the central region is

spiral

which of the following is a characteristic of degenerate matter in a white dwarf star?

the electrons get as close to each other as possible and resist further compression

ninety percent of all stars (if plotted on an H-R diagram) would fall into a region astronomers call

the main sequence

the strongest force we know is

the nuclear force which holds nuclei together

a neutron star is as dense as

the nucleus of an atom

In the formula E=mc², the letter c stands for

the speed of light

Which of the following has the shortest wavelength

x-rays

objects orbiting around the center of the Milky Way obey Kepler's 3rd law. This means that

a cloud of gas or star that is further from the center will generally take more time to orbit

which type pf galaxy os observed to contain mostly older stars?

elliptical

in the sun, when a positron and en electron collide, they will produce

energy in the form of gamma rays

after the core of a massive star becomes a neutron star, the rest of the star's material

explodes outward as a supernova


Related study sets

Chapter 12: Formation of Contracts; Offer and Acceptance

View Set

1. THE BEGINNINGS OF HUMAN SOCIETY

View Set

FIN 300 Chapter 1- Introduction to Corporate Finance

View Set