AST EXAM #2 Chapter 9-11

80 terms by Curonicu 

Ready to study?
Start with Flashcards

Create a new folder

Advertisement Upgrade to remove ads

The most abundant element in the sun (at the moment) is hydrogen.

True

The density in the solar corona is much higher than in the photosphere.

False

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

False

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

False

The sun spins on its axis roughly about

once a month

What is the meaning of the solar constant?

the amount of energy the earth receives per unit area and unit time

The Sun's average density is almost exactly the same as

Jupiter

What two energy transport mechanisms, in order from outside the core to the surface, is found in the Sun?

radiative diffusion, convection

The solar winds blow outward from

coronal holes

A loop of gas following the magnetic field lines between sunspots' poles is

a prominence

As the Sun rotates, an individual sunspot can be tracked across its face. From eastern to western limb, this takes about

two weeks

A maximum in solar activity should next occur about

2012

What natural barrier must be overcome for two protons to collide and fuse together?

electrostatic repulsion

In the proton-proton cycle, the helium atom and neutrino have less mass than the original hydrogen. What happens to the lost mass?

it is converted to energy (E = mc2)
(E equals the velocity of light times the mass squared.)

The solution to the solar neutrino problem which won a Nobel Prize in 2002 was

2/3 of the neutrinos decay into a new form in the 8 minutes to Earth

The stars α Cygni and β Cygni are in the constellation Cygnus. Which statement can we claim is true?

α Cygni appears brighter

The spectral type of a star is primarily a measure of its

Temperature

Which of these stars would be the hottest?

B0

What can be said with certainty about a red star and a blue star

The blue star is hotter than the red star.

Which of these pairs of binaries would appear most similar in color telescopically?

M1V and K9V

In general, what can be said about type O and B stars compared to type K and M stars

They are hotter and younger

The stars with masses comparable to our Sun's, but sizes like the earth are

white dwarfs

In the H-R diagram, what are the two most important (common) types of data plotted

spectral classes (and/or temperature) and absolute magnitude (and/or luminosity)

On the H-R diagram, our Sun lies

about the middle

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

at the top right

Compared to the size of the Sun, stars of all types range from approximately

0.01 to 1,000 solar radii

Binary stars separated enough to be resolved in a telescope are called

visual binaries

If we know the average separation and period of revolution for a binary system, we can then determine

the total mass of the system

What information can be gained from the light curves of eclipsing binaries

their relative sizes and period of orb

Interstellar gas is composed mainly of

90% hydrogen, 9% helium

Which statement about the dark nebulae is true?

They can be penetrated only with longer wavelengths such as radio and infrared

Due to absorption of shorter wavelengths by interstellar dust clouds, distant stars behind the clouds appear

redder

Emission nebulae like M42 occur only near stars that emit large amounts of

ultraviolet radiation

What is the primary visible color of an emission nebula?

red due to ionized hydrogen atoms

What two things are needed to create an emission nebulae

hot stars and interstellar gas, particularly hydrogen

What information does 21 cm radiation provide about the gas clouds?

all of the above

The average temperature of the typical dark dust cloud is about

100 K

When an electron in H changes its spin from the same to the opposite direction as the proton, it

a radio wave photon

On a H-R diagram, a protostar would be

above and to the right of the main sequence

The single most important determinant of the temperature, density, radius, luminosity, and pace of evolution of a protostar is its

mass

How long does it take an M class star to reach the main sequence, compared to a solar type star

about twenty times longer

Which is characteristic of globular star clusters?

old age and hundreds of thousands of stars, only about 30 ly wide

A star's luminosity is

The total amount of energy radiated from its surface per second.

The inner core of the sun where there is no nuclear fusion and no convection is
called the

Radiation zone

What features or structures of the sun can be seen during a total solar eclipse?

The corona and solar flares

What keeps the Sun from exploding or imploding?

Hydrostatic equilibrium between gravity and radiation

The process that we think powers the sun involves what?

The fusion of six initial protons that result in two final protons plus a helium nucleus.

What kind of a "telescope" would you build to make a neutrino detector.

A gigantic container of fluid far under the Earth's surface with some kind of
photodetectors lining the wall, all in total darkness.

How long will a one-solar mass star live on the main sequence?

About 10 billion years

For measuring distances using spectroscopic parallax, what is one of the steps in
the method

The absolute luminosity of the star is inferred from the H-R diagram using "OBAFGKM".

Our Sun has which spectroscopic label?

G2

In any orbiting binary star system, what can the period of the orbit and its
semimajor axis tell you?

the total mass of the binary system

What is the approximate age of a star cluster if its turn-off point is at the position of our sun on the H-R diagram?

about 10 Billion years

Noting the turnoff mass in a star cluster allows you to determine its

age

Approximately how much power could a 1 square meter solar collector receive?

About 1 kilowatt.

The "boiling" effect that characterizes the Sun's surface is described as

Granulation

Open magnetic field lines (pointing out away from the Sun) in low density regions of the corona lead to

Solar wind and coronal mass ejections.

Going out from the center from the Sun, in sequence we have

the core, radiation zone, convection zone, photosphere, chromosphere, corona.

If a one kilogram melon were to be completely turned into energy, how much energy would it produce

9 x 1016 joules E=mc2 = 1kg*(3 x 108 m/s )2 = 9 x 1016 J.

The solar neutrino problem refers to what

The observation that only about 1/3 of the expected neutrino flux from the sun was initially observed, for instance by Davis

The star Altair has a parallax of 0.20 seconds of arc. How far away is it?

5 parsecs d = 1/p = 1/0.2 = 5 parsecs

We see the apparent magnitude of a star from its observed brightness. How is the absolute magnitude of a star defined?

It is the apparent magnitude it would have it were 10 parsecs from us.

Name two main regions where stars appear away from the main sequence in the H-R diagram:

The white dwarf and red giant regions.

If 2.00 kg of mass is converted to energy, how much energy will be produced?

1.80 × 1017 J

If spectroscopic luminosity classification gives us an estimated distance to the faint star SAO 47552 of about 3300 light years, then its parallax would be only

0.001 arcseconds

A star has a parallax of .05 arc seconds, its distance is

20 parsecs

If a 100 kg zombie were to suddenly be completely turned into energy, how much
energy would it produce?

e) 9 x 1018 joules. E = mc2 = 100(3x108)2 = 1009x1016 = 9x1018.

The star Botox 959A has a parallax of 0.01 arc seconds. How far away is it from
Earth?

100 parsecs. d = 1/p = 1/0.01 = 100

A star has a parallax of .05 arc seconds, its distance is

20 parsecs (d = 1/p = 1/0.05 = 20 pc)

Assume that the relationship between the lifetime of a star (in solar lifetimes) is
proportional to the inverse of the mass of a star (in solar masses) cubed, that is:

Eight solar lifetimes. Lifetime = 1/(1/2)3 = 1/(1/8) = 8.

If spectroscopic luminosity classification gives us an estimated distance to the faint star SAO 47552 of about 3300 light years, then its parallax would be about

0.001 arcseconds (note that 3300 LY = 1000 pc, so 1/1000 = 0.001)

The star Lacaille 9352 is 3.58 parsecs from Earth. What is its parallax?

0.279 arcseconds

If a two metric ton (2000 kg) car were to be completely turned into energy, how much energy would it produce?

1.8 x 1020 Joules

The speed of light is 3.00 × 108 m/s. If 2.00 kg of mass is converted to energy, how much energy will be produced

a) 1.80 × 1017 J

Two stars both have parallaxes of 0.023 arseconds, but star A has apparent magnitude 2.3, while star B has apparent magnitude 7.3. Which statement is true?

one magnitude unit corresponds to a change of 2.5 in brightness. So, a difference of 5 in magnitude corresponds to a difference of 100 in brightness, i.e. 2.52.52.52.52.5 ~ 100

Assume that the relationship between the lifetime of a star (in solar lifetimes) is proportional to the inverse of the mass of a star (in solar masses) cubed, that is:
Lifetime = 1/Mass3. So, if a star has a mass that is ten times that of our Sun, how long does it live?

One thousandth of a solar lifetime.

If a star has a parallax of 1 arcsecond, how far away is it?

1 parsec

The closest star to the sun is

Proxima Centauri

Star clusters are good for studying

stellar evolution

The turn off point on the main sequence of a H-R diagram tells us

the average age of a star cluster

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set