Sun Characteristics and Solar Dynamics

Questions and Answers

The most abundant element in the sun is hydrogen.

True

There are as many absorption lines in the solar spectrum as there are elements present in the sun.

False

The density and temperature in the solar corona are much higher than in the photosphere.

False

Sunspots appear dark because they are hotter than the surrounding gas of the photosphere.

False Signup and view all the answers

Flares are caused by magnetic disturbances in the lower atmosphere of the sun.

True Signup and view all the answers

The proton-proton chain releases energy because mass is created in the process.

False Signup and view all the answers

Neutrinos have never been detected experimentally.

False Signup and view all the answers

The sun is roughly:

100 times larger Signup and view all the answers

Astronomers on Venus would measure a solar constant:

Larger than Signup and view all the answers

The sun spins on its axis roughly once each:

Month Signup and view all the answers

A typical solar granule is about the size of:

A larger US state Signup and view all the answers

The time between successive sunspot maxima is about:

A decade Signup and view all the answers

Solar energy is produced by:

Fusion of light nuclei into heavier ones Signup and view all the answers

What is probably responsible for the increase in temperature of the corona far from the sun's surface?

The Sun's magnetism Signup and view all the answers

The proton-proton cycle involves what kind of fusion process?

Hydrogen (H) into helium (He) Signup and view all the answers

The light from the East limb (edge) of the Sun is blue shifted and the light from the West limb is redshifted. This is because:

The Sun is rotating. Signup and view all the answers

The photosphere (the visible surface) of the Sun is like:

An apparent surface; you would notice very little change as you go through it, like flying through a cloud. Signup and view all the answers

Sunspots appear dark because they are:

A bit cooler, thus dimmer than the rest of the photosphere. Signup and view all the answers

How much bigger is the Sun's radius compared to Earth's radius?

100 Signup and view all the answers

The density of the Sun is most similar to that of:

Jupiter. Signup and view all the answers

Tremendous pressure is created at the Sun's center due to its own gravity. The Sun is kept from collapsing by:

Gas pressure created by the heat of nuclear fusion. Signup and view all the answers

Star A appears brighter than star B, as seen from Earth. Therefore, star A must be closer to Earth than star B.

False Signup and view all the answers

A star of apparent magnitude +5 looks brighter than one of the apparent magnitude +2.

False Signup and view all the answers

Red giants are very bright because they are extremely hot.

False Signup and view all the answers

The radius of a star can be determined if the star's distance and luminosity are known.

False Signup and view all the answers

Astronomers can distinguish between main sequence and giant stars by purely spectroscopic means.

True Signup and view all the answers

In a spectroscopic binary, the orbital motion of the component stars appears as variations in the overall apparent brightness of the system.

False Signup and view all the answers

There are no billion-year-old main sequence O or Type B stars.

True Signup and view all the answers

From a distance of 1 parsec, the angular size of Earth's orbit would be:

2 arc seconds Signup and view all the answers

Compared with a star of absolute magnitude -2 at a distance of 100 pc, a star of absolute magnitude 5 at a distance of 10 pc will appear:

Fainter Signup and view all the answers

Stars of spectral class M do not show strong lines of hydrogen in their spectra because:

Their surfaces are so cool that most hydrogen is in the ground state. Signup and view all the answers

Cool stars can be very luminous if they are very:

Large Signup and view all the answers

The mass of a star may be determined by:

Studying its orbit around a binary companion. Signup and view all the answers

Solar energy is produced by:

Fusion of light nuclei into heavier ones. Signup and view all the answers

How many radians are in 60 degrees?

π/3 Signup and view all the answers

If the parallax of a star is measured to be 0.1 seconds of arc, its distance is:

10 parsecs Signup and view all the answers

How far away from Earth is the nearest star?

1 AU Signup and view all the answers

For two stars of the same apparent brightness, the star closer to the Sun will generally have:

A lower luminosity Signup and view all the answers

Two identical stars, one 5 ly from Earth, and a second 50 ly from Earth are discovered. How much fainter does the farther star appear to be?

<ol start="100"> <li></li> </ol> Signup and view all the answers

In the stellar magnitude system invented by Hipparchus, a smaller magnitude indicates a _____ star.

Brighter Signup and view all the answers

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

Ten parsecs. Signup and view all the answers

Which of the following quantities do you need in order to calculate a star's luminosity?

A and D Signup and view all the answers

Wien's law tells us that the hotter an object, the _____ the peak wavelength of its emitted light.

Shorter Signup and view all the answers

Two stars have the same surface temperature, but the radius of one is 10 times that of the other. The larger star is:

100 times as luminous Signup and view all the answers

Interstellar matter is quite evenly distributed throughout the Milky Way galaxy.

False Signup and view all the answers

Emission nebulae radiate mainly in the ultraviolet part of the electromagnetic spectrum.

False Signup and view all the answers

Twenty-one centimeter radiation can be used to probe the interiors of molecular clouds.

False Signup and view all the answers

More massive stars form more rapidly.

True Signup and view all the answers

Brown dwarfs take a long time to form, but will eventually become visible as stars on the lower main sequence.

False Signup and view all the answers

The formation of the first high-mass stars in a collapsing cloud tends to inhibit further star formation within that cloud.

True Signup and view all the answers

Most stars form as members of groups or clusters.

True Signup and view all the answers

The red glow of an emission nebula:

Is produced by hydrogen gas heated to high temperatures by massive stars within the nebula. Signup and view all the answers

Of the following telescopes, one best suited to observing dark dust clouds is:

A radio telescope Signup and view all the answers

A protostar that will eventually turn into a star like the sun is significantly:

More luminous Signup and view all the answers

Some regions of the Milky Way's disk appear dark because:

Stars in that direction are obscured by interstellar dust. Signup and view all the answers

The reddish color of emission nebulae indicates that:

Hydrogen gas is present. Signup and view all the answers

If an interstellar cloud contracts to become a star, it is due to which force?

Gravitational Signup and view all the answers

Stars are formed from cold interstellar gas clouds made up of:

Molecular hydrogen gas and dust grains. Signup and view all the answers

Objects more massive than our Sun form into stars:

Much faster, over tens of thousands of years. Signup and view all the answers

Which spectral classification and type corresponds to a star like the Sun?

G2V Signup and view all the answers

Interstellar gas is composed primarily of:

90% hydrogen, 9% helium, and 1% heavier elements. Signup and view all the answers

Astronomers use the term nebula to refer to:

All of the above are correct. Signup and view all the answers

All of the single red-dwarf stars that ever formed are still on the main sequence.

True Signup and view all the answers

The sun will get brighter as it begins to run out of fuel in its core.

True Signup and view all the answers

A planetary nebula is the disk of matter around a star that will eventually form in a planetary system.

False Signup and view all the answers

Nuclear fusion in the core of a massive star cannot create elements much heavier than iron.

True Signup and view all the answers

A nova is a sudden outburst of light coming from an old main sequence star.

False Signup and view all the answers

It takes less and less time to fuse heavier and heavier elements inside a high mass star.

True Signup and view all the answers

In a core collapse supernova, the outer part of the core rebounds from the inner, high-density core, destroying the entire outer part of the star.

True Signup and view all the answers

Because of stellar nucleosynthesis, the spectra of old stars show more heavy elements than those of young stars.

False Signup and view all the answers

A white dwarf is supported by the pressure of tightly packed:

Electrons Signup and view all the answers

A star like the sun will end up as a:

White dwarf Signup and view all the answers

A white dwarf can dramatically increase in brightness only if it:

Has another star nearby Signup and view all the answers

Nuclear fusion in the sun will:

Create elements up to and including oxygen Signup and view all the answers

Most of the carbon in our bodies originated in:

The core of a giant red star Signup and view all the answers

What is a T-Tauri star?

A protostar about to become a star Signup and view all the answers

A star like our Sun will spend most of its 'shining' lifetime:

As a main-sequence star. Signup and view all the answers

The Sun will evolve away from the main sequence when:

Helium builds up in the core, while the hydrogen-burning shell expands. Signup and view all the answers

Elements heavier than carbon were created:

By nucleosynthesis in massive stars. Signup and view all the answers

A white dwarf can explode when:

Its mass exceeds the Chandrasekhar limit. Signup and view all the answers

Study Notes

Sun Characteristics

Hydrogen is the most abundant element in the Sun; mass is converted to energy during fusion processes.
Solar flares are a result of magnetic disturbances occurring within the Sun's lower atmosphere.
The Sun's diameter is approximately 100 times larger than that of Earth.

Solar Phenomena and Properties

Sunspots appear dark because they are cooler than the surrounding photosphere.
The solar corona has a lower density and temperature compared to the photosphere.

Energy Production

Solar energy is generated through the fusion of light nuclei, specifically hydrogen into helium.
The process of fusion releases vast amounts of energy due to the conversion of mass into energy according to Einstein's equation, E=mc².

Solar Dynamics

The Sun rotates on its axis approximately once per month.
Coronal heating is likely caused by the Sun's magnetic fields rather than fusion reactions.

Stellar Properties and Measurements

A star's luminosity is analyzed by studying its orbit around a binary companion and measuring its apparent brightness and distance.
Stars of spectral class M do not show strong hydrogen lines due to their cool temperatures that keep hydrogen in the ground state.

Star Formation and Evolution

Massive stars form more quickly than smaller ones, taking only tens of thousands of years.
The red glow of emission nebulae indicates the presence of hydrogen gas heated by surrounding massive stars.

Spectroscopic Characteristics

Astronomers can distinguish between main sequence and giant stars using spectroscopic methods.
A white dwarf gains brightness when in a binary system, particularly when material is accreted from a companion star.

Stellar Life Cycle

Stars evolve based on their mass; the lifecycle includes stages like main sequence, red giant, and potentially ending as a white dwarf.
Supernovae and neutron stars contribute to the nucleosynthesis of heavier elements.

Cosmic Measurements

Stars separated by greater distances appear fainter due to the inverse square law of brightness; the further a star, the less luminous it appears.
Interstellar gas comprises mostly hydrogen and helium, with heavier elements making up a minor percentage.

Types of Stars

T-Tauri stars represent a specific stage of star development shortly before entering the main sequence.
Red giants are characterized by their large size but are not necessarily hotter than smaller stars.

Element Formation

Critical elements like carbon are produced in giant red stars and released upon their death, contributing to the cosmic material from which new stars and planets form.
Elements heavier than iron are primarily synthesized through nucleosynthesis in massive stars during their life cycle.

Overall Conclusions

Stellar characteristics, energy production, and life cycles illustrate the complex processes governing the universe, and understanding these aids in comprehending cosmic evolution and the formation of planetary systems.

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Description

Explore the fascinating characteristics and dynamics of the Sun, including its energy production, solar phenomena, and unique properties. This quiz covers key concepts such as fusion processes, sunspots, and coronal heating. Test your knowledge and deepen your understanding of our closest star!