chapter 10 py

Nebula is just another name for the interstellar medium (ISM).

true

Calculations of the Sun's future evolution indicate that it will blow away almost half of its mass in several relatively short episodes about 4 to 5 billion years from now before it is finally extinguished.

false

The composition of the interstellar dust suggests that it is formed primarily in the atmospheres of cool stars.

true

​Which type of nebulaeare twisted and distorted clouds of gas and dust dense enough to obstruct the view of the more distant stars?

\n ​dark nebulae

H I clouds can be observed using _____.

21 cm radiation

​Which telescope imaged the center of the Milky Way Galaxy at a wavelength of 8 microns to reveal the distribution of the dusty interstellar medium?

Spitzer Space Telescope

Coronal gas emits x-rays and has temperatures of ____.

10^6 K or higher

​Observing at a wide range of wavelengths, astronomers have detected more than ______ different molecules in the ISM.

150

At infrared wavelengths, the ISM glows with blackbody radiation emitted by the interstellar dust. 

true

Elements such as carbon, silicon and oxygen have been produced in stars and expelled as stars age in the interstellar medium. This is most likely due to these elements having cooled and condensed from aging stars to form dust grains, and carried out by a powerful winds.

true

Because blue light has a shorter wavelength than red light, it will be more readily scattered.

true

H II Regions are also called emission nebulae.

true

​Which type of nebulae is produced when short-wavelength scatters from the dust and displays a blue hue?

reflection nebulae

​What is the most abundant element in the interstellar medium?

hydrogen

Interstellar extinction and the reddening of light by the interstellar medium (ISM) are both caused by _____.

only dust in the ISM

The intercloud medium is believed to make up 90 percent of the mass of the interstellar medium.

false

X-rays come from certain regions of the interstellar medium because gas molecules in those regions are at a very high density.

false

​Which type of nebula is produced when a star, hotter than 25,000 K, excites the gas near it to produce an emission spectrum producing a distinctive pink color?

emission nebulae

​Which mission passed the *bow shock* in the Universe?

Voyager I

​Large molecular clouds will form into protostars because of ____.

gravitational contraction

Stars are born in reflection nebulae.

false

Stars are born from the interstellar medium, and aging or dying stars return gas and dust back into the interstellar medium.

true

​The interstellar medium is composed of mainly _____.

mostly gas and some dust

The ground state of hydrogen has two closely-spaced energy levels, where one-electron is spinning up and the other is spinning down. This energy transition corresponds to releasing excess energy as a photon at what wavelength?

21 centimenters

The coronal gas in the interstellar medium has very high temperatures similar to the Sun's corona.

true

Molecular clouds are mapped using _____ gas instead of the most-abundant hydrogen because it radiates at radio wavelengths more efficiently.

carbon monoxide

​Which mission is mapping the heliosphere's boundary?

interstellar boundary explorer

The spacecraft ________ captured particles that scientists believe came from the ISM.

Stardust

The ISM is easily visible to human eyes.

false

Which molecule has not been detected in molecular clouds?

All of these have been detected

​The emission lines from O III are called ____ because they are not visible laboratories on Earth due to the much greater pressure of the gas on Earth.

forbidden lines

​The pressure of a gas depends on the ____ and ____ of the gas.

temperature; density

​Molecules in the interstellar medium emit radiation at what wavelengths?

radio