Astro 2

The order of evolutionary stages of a star like the Sun would be Main Sequence, giant, planetary nebula, and finally ______. neutron star black hole none of these nova

The helium flash converts helium to the heavier element _____. iron nitrogen carbon boron

In a white dwarf, we have packed the mass of the Sun into the volume of Earth, so the density is: hundreds of times greater than normal matter. trillions of times greater than iron. a million times that of the Sun. thousands of times denser than water.

The brightest stars of a young open cluster will be: yellow main sequence stars like the Sun massive blue main sequence stars red giants T Tauri variables

A high-mass star dies more violently than a low-mass star because: It is most often found as part of a binary system. It generates more heat and its core eventually collapses. It cannot fuse elements heavier than carbon. Gravity is weakened by its high luminosity.

Which of these will the Sun probably become in the very distant future? supernova nova planetary nebula pulsar

What is a typical age for a globular cluster? 200 million years 2 billion years 10 million years 12 billion years

What are black dwarfs? objects that are not quite massive enough to be stars the lowest mass main sequence stars cooled off white dwarfs the end result of massive star evolution

What is a planetary nebula? A planet surrounded by a glowing shell of gas. The ejected envelope of a red giant surrounding a stellar core remnant. A type of young, medium mass star. The disc of gas and dust surrounding a young star that will soon form a solar system.

A star spends most of its life: as a protostar. as a red giant or supergiant. as a main sequence star. in explosions lasting millions of years.

What makes the subject of star formation so difficult and complex? Stars live too long to be observed from birth to death. Clouds, fragments, protostars, stars, and nebulae all interact and influence each other. Star formation is too expensive to study in detail. Shock waves disrupt the orderly evolution of stars.

A typical protostar may be several thousand times more luminous than the Sun. What is the source of this energy? The ionization of the gas as it heats up. From nearby hot stars or supernovae that have initiated the star formation process. Nuclear fusion in its core. From the release of gravitational energy as the protostar continues to shrink.

What is the critical temperature at which hydrogen can fuse into helium in the star's core? 100 million K. 10 million K. 10,000 K. 1 million K.

What happens when an interstellar cloud fragment shrinks? Density rises. Pressure increases. Temperature rises. All of these.

Most stars probably formed: in the nucleus of the Galaxy. in clusters. from planetary nebulae. alone.

How long does it take for a star like our Sun to form? 3 billion years. 10 thousand years. 1 million years. 50 million years.

What is the key factor that determines the temperature, density, radius, luminosity, and pace of evolution of a protostellar object? Heat Rotation Magnetism Mass

For gravity to contract a spinning interstellar cloud, there needs to be sufficient: Heat. Mass. Magnetism. Rotation.

If the initial interstellar cloud in star formation has a mass sufficient to form hundreds of stars, how does a single star form from it? One star forms at its center and blows the rest of the matter back into space. The cloud is disrupted by rotation so that it reduces its mass down to that of a typical star. One star forms and the rest of the matter goes into making planets, moons, and other objects of a solar system. The cloud fragments into smaller clouds and forms many stars at one time.

A cloud fragment too small to form a star becomes: A brown dwarf. Nothing, it simply dissipates. A T Tauri star. A black hole.

Which event marks the birth of a star? Formation of a photosphere. Collapse of an interstellar cloud. Fusion of hydrogen atoms into helium atoms. Instability in an interstellar cloud.

How many hydrogen atoms does it take to make a typical star? 10^25 10^18 10^10 10^57

Evidence for star formation theory comes from: Studying different objects at different stages and piecing together an evolutionary picture. Tracking one star through time. Plotting stars on the Hertzsprung-Russell diagram. Emission nebulae, exclusively.

When a typical open cluster forms, which type of stars are formed most often? low mass M type dwarfs massive blue main sequence white dwarfs red giants

Nearly all the elements found in our environment were formed inside stars, except for: Silver and technetium. Oxygen and carbon. Iron and nickel. Hydrogen and helium.

The production of which element in the core of a highly evolved giant leads to type II supernovae? helium iron carbon uranium

What is the only way that a white dwarf can suddenly explode in a type I supernova? if it finally cools off to under 2,000 K and collapses as a black dwarf if another star collides with it if it is a member of a mass-transfer binary if it passes through a large dust cloud

How long does it take a stellar iron core to collapse? One year 200 years One second Millions of years

The heaviest nuclei of all are formed: During a nova explosion During the triple alpha process By neutron capture during a supernova explosion During carbon burning

An iron core cannot support a star because: Iron supplies too much pressure. Iron cannot fuse with other nuclei to produce energy. Iron has poor nuclear binding energy. Iron is in the form of a gas, not a solid, in the center of a star.

The upper mass limit of 1.4 solar masses for white dwarfs won a Nobel prize for: Schwartzschild Chandrasekhar Einstein Hubble

What is the total energy radiated by a supernova equal to? 1 billion Suns 1 million Suns 1 trillion Suns 1,000 Suns

The observed slowing of a clock in the vicinity of a black hole is a prediction of: General relativity. The Principle of Cosmic Censorship. Stellar nucleosynthesis. Special relativity.

Almost half of all known millisecond pulsars are found in what type of object? open clusters emission nebulae planetary nebulae globular clusters

The supernova of 1054 AD produced: a remnant still visible to the naked eye, the Crab Nebula, M-1. the most famous black hole. a pulsar with a period of 33 milliseconds, visible optically. no remaining visible trace, as it was a type I supernova.

In the Lighthouse model, if the beams sweeps across us, we can observe the pulse. pulsars are navigational devices created by interstellar navigators. all pulsars have their poles pointed directly at us. the period of pulsation must speed up as the neutron star continues contracting.

What would happen if mass is continually added to a 1.4 solar mass neutron star? The star's radius would increase. All of these. The star would erupt as a supernova. The star would eventually become a black hole.

What would happen if mass is added to a 1.4 solar mass white dwarf? The star would eventually become a black hole. The star's radius would increase. The star would erupt as a type I supernova. The core would collapse as a type II supernova.

In a "hypernova", the very energetic supernova creates a: planetary nebula, then planets themselves around a pulsar. very visible supernova remnant. millisecond pulsar. black hole.

While perhaps affected by rotation and magnetism, we think the lower limit for black holes is: Schwartzchild's limit of 3 solar masses. Chandrasekhar's limit of 1.4 solar masses. Kelvin's limit of 0.08 solar masses. Einstein's limit of 25 solar masses for the main sequence stars.