question

The ESA satellite which gave us our most accurate distances to stars is called

answer

Hippacros

question

If two stars differ in brightness by 5 magnitudes, the light ratio received by us is ______ to 1

answer

100x

question

In comparing first magnitude Deneb with second magnitude Polaris, we find that

answer

Deneb appears 2.5x brighter to us than Polaris

question

What are the two most important intrinsic properties used to classify stars?

answer

Luminosity and Surface Temperature

question

If a star has a parallax of 0.05", then its distance in light years is about

answer

66 Light Years

question

If a star is found by spectroscopic observations to be about 500 parsecs distant, its parallax is

answer

.002"

question

Hipparcos observations have given us good data on stars out to about

answer

200 parsecs

question

About how many stars has Hipparcos given us accurate distance data on?

answer

A million, those with parallaxes of .005" or large

question

Which of the following spectral types is the hottest? K4 G2 G5 H3

answer

G2

question

While Sirius, the Dog Star, is type AO, a star just a step hotter than M0 is a related: M1 K9 B9 A1

answer

K9

question

The Hertzsprung-Russell Diagram plots ______ against the spectral type or temperature.

answer

Luminosity or Absolute Magnitude

question

Two stars which differ by 5 magnitudes in apparent brightness have the same parallax; thus, one star must be intrinsically ______ times as luminous as the other.

answer

A hundred

question

Stellar masses are determined directly by observation of the orbits and periods of ______ stars.

answer

All types of binary

question

In what range of masses are most stars found

answer

.1 to 20 solar masses

question

Why are star clusters almost ideal "laboratories" for stellar studies?

answer

Stars in clusters have the same age, similar composition, and are at the same distance away

question

Perhaps the greatest of the Greek astronomers, _______ compiled the first catalog of stars, accurately measured their positions, and defined the basic system of stellar brightnesses.

answer

Hipparcos

question

Which of the following spectral types is the hottest? A5 O9 G2 K9

answer

O9

question

Which of these pairs of spectral types is most similar in temperature? M2 and M5 B1 and A1 K9 and M0 F1 and G9

answer

K9 and M0

question

What physical property of a star does the spectral type measure?

answer

Temperature

question

The star's color index is a quick way of determining its

answer

Temperature

question

Which of the following is the most common type of star?

answer

Main Sequence

question

Which of the following apparent magnitudes is the brightest? +3.2 +5.0 -1.1 +15.8

answer

-1.1

question

What is the absolute magnitude of our Sun? -23 +4.8 +9.32 -1.4

answer

+4.8

question

What is the single most important characteristic in determining the course of a star's evolution?

answer

Mass

question

The absolute magnitude of a star is its brightness as seen from a distance of

answer

10 parsecs

question

Which statement about stellar motion is incorrect? the transverse velocity is measured by the proper motion the Pythagorean theorem relates space, transverse, and radial velocities. proper motion is measured over intervals of exactly six months the radial velocity is measured by the Doppler shift

answer

proper motion is measured over intervals of exactly six months

question

If the radial velocity were -3 km/sec, and the transverse velocity were +4 km/sec, then

answer

The space velocity would be 5 km/sec.

question

What characteristic of the stars in a binary system can be determined by knowing the period of the stars' common orbit and the distance between them?

answer

Mass

question

Which type of binary can have their sizes measured directly by photometry?

answer

Eclipsing

question

The HR diagram can be a plot of _________.

answer

absolute magnitude versus color index

question

What is the typical main sequence lifetime of a B-type star?

answer

20 million years

question

What is the typical main sequence lifetime of a G-type star?

answer

10 billion years

question

What is the typical main sequence lifetime of a M-type star?

answer

A trillion years

question

A nearby star has a parallax of 0.2 arc seconds. What is its distance?

answer

5 pc

question

Procyon lies about 13 light years distant, thus its parallax is about:

answer

.25"

question

In the H-R diagram, the bright blue-white stars that dominate the naked eye sky lie to the

answer

Upper left quadrant

question

On the H-R diagram, the Sun lies:

answer

About the middle of the main sequence

question

On the H-R diagram, white dwarfs lie Sirius B and Procyon B lie:

answer

To the lower left

question

On the H-R diagram, red supergiants like Betelguese lie:

answer

To the top right

question

______ have masses like that of the Sun, and radii like that of the Earth.

answer

White dwarfs

question

What is proper motion?

answer

It is the annual apparent motion of a star across the sky

question

In order to turn a star's proper motion into its space velocity, we must also know:

answer

Its distance and radial velocity

question

Which of the following best describes the size and distance relationship of our Sun and the nearest star?

answer

Two golfballs separated by 100 kilometers

question

Compared to the size of the Sun, in what range of sizes are most stars found?

answer

0.01 to 100 solar radii

question

How might the most common occurring stars be described, based on our stellar neighborhood?

answer

M-type main sequence stars

question

What are the characteristics of an open cluster of stars?

answer

a few hundred, mostly main sequence, stars

question

What are the characteristics of globular cluster stars?

answer

old age and hundreds of thousands of stars

question

What makes the subject of star formation so difficult and complex?

answer

Stars live too long to be observed from birth to death.

question

A typical protostar may be several thousand times more luminous than the Sun. What is the source of this energy?

answer

From the release of gravitational energy as the protostar continues to shrink

question

Which of these is not typical of a condensing protostar?

answer

Fusion of helium into carbon in their cores

question

What is the critical temperature at which hydrogen can fuse into helium in the star's core?

answer

10 million K

question

What happens when an interstellar cloud fragment shrinks?

answer

Density rises. Temperature rises. Pressure increases

question

What is characteristic of a main sequence star

answer

The rate of nuclear energy generated in the core equals the rate radiated from the surface.

question

Most stars probably formed

answer

In clusters

question

How long does it take for a star like our Sun to form

answer

50 million years

question

Which relationship concerning the mass of protostars is false The more massive ones will be the hottest and most luminous. The more massive ones will reach the main sequence first. The more massive ones glow red, accounting for the color of H II regions. The more massive ones create the ultraviolet to cause H II regions to glow

answer

The more massive ones glow red, accounting for the color of H II regions

question

What is the key factor that determines the temperature, density, radius, luminosity, and pace of evolution of a protostellar object

answer

Mass

question

When an H II region is observed, it signals what stage in stellar formation

answer

Depending on their masses, the stars inside may be at different stages of formation

question

What is the size of a typical interstellar cloud that is dense enough to form stars

answer

10 pc

question

For gravity to contract a spinning interstellar cloud, there needs to be sufficient

answer

Mass

question

As a star forms, the photosphere first appears

answer

When the protostar forms

question

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

answer

The cloud fragments into smaller clouds and forms many stars at one time.

question

A cloud fragment too small to form a star becomes

answer

A brown dwarf

question

Which event marks the birth of a star

answer

Fusion of hydrogen atoms into helium atoms

question

At what stage of evolution do T Tauri stars occur

answer

When a protostar is on the verge of becoming a main sequence star

question

How many hydrogen atoms does it take to make a typical star

answer

10^57

question

How are T Tauri stars characterized observationally

answer

By sudden changes in their brightness

question

Evidence for star formation theory comes from

answer

Studying different objects at different stages and piecing together an evolutionary picture.

question

How long does it take an M-type star to form, compared to the time for a solar-type star to form

answer

20 times as long

question

When a typical open cluster forms, which type of stars are formed most often

answer

low mass M type dwarfs

question

A star will evolve "off the main sequence" when it uses up which of the following?

answer

most of the hydrogen in the core

question

On the main sequence, massive stars do which of the following

answer

burn their hydrogen fuel more rapidly than the Sun

question

When the Sun is on the red-giant branch, it will be found where on the H-R diagram

answer

Upper right

question

After the core of a Sun-like star starts to fuse helium on the horizontal branch, the core becomes which of the following

answer

hotter

question

When the Sun leaves the main sequence, it will become which of the following

answer

brighter

question

A star like the Sun will end up as what

answer

a white dwarf

question

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

answer

none of these

question

The helium flash converts helium to the heavier element _____

answer

Carbon

question

How many helium atoms must be fused at 100 million K in the helium flash

answer

Three

question

Which of the following best describes the evolutionary track followed in the HR diagram for the most massive stars

answer

Horizontally right

question

What is used, observationally, to determine the age of a star cluster?

answer

the luminosity at the main-sequence turnoff

question

What is the source of pressure in the core of a red giant that resists the force of gravity

answer

electrons which have become incompressible

question

In a white dwarf, we have packed the mass of the Sun into the volume of Earth, so the density is

answer

a million times that of the Sun

question

What, in addition to its HR diagram, is needed to age-date a star cluster

answer

theoretical models of stellar evolution

question

What characteristic of a star cluster is used to determine its age

answer

the main sequence turnoff

question

The brightest stars of a young open cluster will be

answer

massive blue main sequence stars

question

In globular clusters, the brightest stars will be:

answer

Red supergiants

question

A high-mass star dies more violently than a low-mass star because

answer

It generates more heat and its core eventually collapses.

question

A ______ is a relatively gentle mass-loss event which allows a star to peacefully readjust its structure into a white dwarf configuration

answer

planetary nebula

question

Which of these will the Sun probably become in the very distant future

answer

planetary nebulae

question

The evolution of stars appears inevitable. But what likely circumstance can radically alter this evolutionary sequence

answer

The stars can be in a short period binary system.

question

Which statement is true, in terms of stellar evolution

answer

sooner or later, gravity wins

question

Can a star become a red giant more than once

answer

yes

question

Which statement about blue stragglers is false

answer

They are much more massive than any other stars known

question

If one star of a binary fills its Roche lobe and is spilling matter onto the other, then the system is a:

answer

mass-transfer binary

question

If two stellar cores share a single envelope, we have a:

answer

Contact binary

question

What results from the mass loss from K and M red giants

answer

The wind is rich in dust particles and molecules, including diamonds

question

In a star cluster, just as the most massive stars are evolving into giants and supergiants, what is happening for the lowest mass stars

answer

They are just starting to approach the zero-age main sequence

question

Luminous hot stars and luminous cool stars

answer

have stellar winds, but each are driven by a different source

question

What is a typical age for a globular cluster

answer

12 billion years

question

What temperature is needed to fuse helium

answer

100 million K

question

What are black dwarfs?

answer

Cooled off white dwarfs

question

Which of the following is true regarding planetary nebulae

answer

They are the ejected envelopes of highly evolved low-mass stars

question

The Roche lobe of a star in a binary star system

answer

is, in terms of the star's gravity, its "zone of influence."

question

What is a planetary nebula

answer

The ejected envelope of a red giant surrounding a stellar core remnant.

question

Astronomers talk about "low-mass" and "high-mass" stars with regard to their evolution. In units of solar masses, what is the dividing line, that is, the lowest mass for a high-mass star

answer

8 solar masses

question

What inevitably forces a star like the Sun to evolve away from being a main sequence star

answer

It builds up a core of helium

question

In the evolution of massive stars, what is the significance of the temperature 600 million K?

answer

It is the temperature needed for carbon burning

question

A star spends most of its life

answer

as a main sequence star.

question

What is the significance of 100 million K to the core of a star

answer

Temperature need to start triple alpha process and turn helium into carbon.

question

The "helium flash" occurs at what stage in stellar evolution

answer

Red giant

question

Just as a low-mass main sequence star runs out of fuel in its core, it actually becomes brighter. How is this possible

answer

The core contracts, raising the temperature of the region of hydrogen shell-burning

question

A white dwarf can dramatically increase in brightness only when which of the following applies

answer

It has another star nearby

question

Which of the following stars will become hot enough to form elements heavier than oxygen

answer

A Star that is eight times more massive than the Sun.

question

When does a massive star become a supernova

answer

When it forms iron in its core

question

An observable supernova should occur in our Galaxy how often

answer

About once every century

question

Which one of the following does not provide evidence that supernovae have occurred in our Galaxy

answer

The existence of binary stars in our galaxy

question

Most of the carbon in our bodies originated where

answer

the core of a red giant star

question

The silver atoms found in jewelry originated where

answer

A supernova

question

A surface explosion on a white dwarf, caused by falling matter from the atmosphere of its binary companion, creates what kind of object

answer

Nova

question

For a nova to occur, the system must have already been a:

answer

mass-transfer binary

question

Which type of heavy atomic nuclei are most common, and why

answer

Even numbered elements, for helium is "giant food" for everything beyond itsel

question

Nearly all the elements found in our environment were formed inside stars, except for

answer

Hydrogen and helium

question

The production of which element in the core of a highly evolved giant leads to type II supernovae

answer

Iron

question

Why does neutron capture work

answer

Neutrons have no repulsive barrier to overcome in combining with positively charged nuclei

question

What is the only way that a white dwarf can suddenly explode in a type I supernova

answer

If it's a member of a mass-transfer binary system

question

What is stellar nucleosynthesis

answer

The formation of heavier elements inside stars

question

Of the elements in your body, the only one not formed in stellar nucleosynthesis is

answer

Hydrogen

question

How long does it take a stellar iron core to collapse

answer

One second

question

The heaviest nuclei of all are formed

answer

By neutron capture during a supernova explosion

question

An iron core cannot support a star because

answer

iron cannot fuse with other nuclei to produce energy.

question

What direct evidence do astronomers have that supports the heavy element formation in stars

answer

Light curves of type-I supernovae Gamma-ray emissions from decay of cobalt-56 in supernovae Observed elemental abundances

question

What was most surprising about SN1987A

answer

The parent star was a B supergiant, not a red supergiant.

question

The upper mass limit of 1.4 solar masses for white dwarfs won a Nobel prize for

answer

Chandrasekhar

question

The Chandrasekhar mass limit is ______.

answer

1.4 solar masses

question

A 20 solar mass star has a main sequence lifetime of 10 million years, yet its iron core exists for only about how long

answer

Less than a day

question

A 20 solar mass star has a main sequence lifetime of 10 million years, yet its iron core exists for only about how long

answer

less than a day

question

As a star evolves, heavier elements tend to form by various processes. Which of the following is not one of these processes

answer

Neutronization

question

What is the reason a type-II supernova slows its dimming after about 2 months

answer

Energy is released from the decay of radioactive cobalt-56 to iron-56

question

The transformation of cobalt 56 into iron 56 is an example of

answer

the weak force and nuclear fission

question

The making of abundant iron nuclei is typical of

answer

type II supernovae

question

What made supernova 1987a so useful to study

answer

its progenitor had been observed previously being in the Large Magellanic Cloud, its distance was immediately known it occurred in modern times and within easy reach of large telescopes

question

Where was supernova 1987a located

answer

In our companion galaxy, the Large Magellanic Cloud

question

Which of these is least likely to happen

answer

recurrent supernovae of type I

question

Which of these is the likely progenitor of a type I supernova

answer

a mass-transfer binary, with the white dwarf already at 1.3 solar masses

question

Which of these is the likely progenitor of a type II supernova

answer

an evolved red giant which is just starting to make silicon in its core

question

Which of the following does not fit a type I supernova

answer

Implosion-explosion of the core of a massive star

question

A star can be a supernova

answer

once

question

The supernova that formed M-1, the Crab Nebula, was observed in what year

answer

1054 AD by the Chinese

question

What is the amount of energy emitted in the form of neutrinos, during a supernova explosion, compared to the amount of energy radiated as electromagnetic radiation

answer

100 times as much

question

What is the total energy radiated by a supernova equal to?

answer

1 billion suns

question

The total energy emitted by the brightest nova explosions is about

answer

1 million suns

question

What produces a type-I supernova

answer

Mass transfer to a white dwarf in a binary where the Chandrasekhar mass is exceeded

question

When helium capture occurs with a carbon-12 nucleus, what results

answer

oxygen-16

question

When two silicon-28 nuclei fuse, the initial result is

answer

nickel-56

question

What evidence is there that supernovae really have occurred

answer

Supernova remnants. Crab Nebula. The explosions themselves

question

When a stellar iron core collapses, large numbers of neutrinos are formed, then

answer

They immediately pass through the core and escape to space

question

A recurrent nova can eventually build up to a

answer

type I supernova

question

In order of visual luminosity at the start, which is most luminous

answer

a type I supernova

question

Which of these do not depend on a mass-transfer binary to occur

answer

a type II supernova

question

The alpha process tends to produce chiefly

answer

even numbered elements

question

Which of the following is not an argument for Cygnus X-1's being a true black hole

answer

The mass of the visible B star is even greater than Cygnus X-1, at around 30 solar masses

question

What explanation does general relativity provide for gravity

answer

Gravity is a result of curved spacetime

question

What makes the Crab pulsar somewhat unusual among pulsars in general

answer

It is rather bright at visible wavelengths.

question

Three terrestrial planetary-sized masses have been discovered orbiting what type of object

answer

a millisecond pulsar

question

What compelling evidence links pulsars to neutron stars

answer

Only a small rotating source of radiation is thought to be able to emit precisely timed pulses such as those from pulsars

question

The key to identifying a black hole candidate in a binary system is the following

answer

the unseen companion in the system must have a sufficiently high mass

question

The observed slowing of a clock in the vicinity of a black hole is a prediction of

answer

General Relativity

question

Which of these is least likely to exist

answer

a 1.8 solar mass white dwar

question

Almost half of all known millisecond pulsars are found in what type of object

answer

globular clusters

question

Who discovered the first object that eventually became known as a pulsar

answer

Jocelyn Bell

question

Who received the Nobel Prize in Physics for relating pulsars to neutron star formation

answer

Anthony Hewish

question

The supernova of 1054 AD produced

answer

a pulsar with a period of 33 milliseconds, visible optically.

question

Which of the following is not a property of the first discovered pulsar (nor any other pulsar)

answer

emissions only in the visible part of the spectrum

question

In the Lighthouse model

answer

if the beams sweeps across us, we can observe the pulse

question

What are X-ray bursters

answer

They are neutron stars on which accreted matter builds up, then explodes in a violent nuclear explosion

question

What is Cygnus X-1?

answer

A leading candidate for being a black hole

question

X-ray bursters occur in binary star systems. What are the two types of stars that must be present to make up such an object

answer

a main sequence or giant star and a neutron star

question

Which of the following are attracted by gravity

answer

any object with mass electromagnetic radiation neutrinos

question

Which of the following can actually escape a black hole? none of these very high energy gamma-rays very low energy radio waves electrons

answer

None of these

question

In a "hypernova", the very energetic supernova creates a:

answer

black hole

question

While perhaps affected by rotation and magnetism, we think the lower limit for black holes is

answer

Schwartzchild's limit of 3 solar masses

question

Which statement about gamma ray bursts is not correct They seem to be coming from far beyond the Milky Way, in other host galaxies. In seconds, they seem to radiate hundreds of times more energy than do supernovae. They are a scaled up version of the X-ray bursts, with more massive stars involved. Millisecond flickering implies they can be only a few hundred kilometers in size.

answer

They are a scaled up version of the X-ray bursts, with more massive stars involved.

question

What would happen if mass is added to a 1.4 solar mass white dwarf

answer

The star would erupt as a type I supernova

question

What would happen if mass is continually added to a 1.4 solar mass neutron star

answer

The star would eventually become a black hole

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