Some of the most beautiful extended objects that we can see are HII regions, or diffuse or emission nebulae. So-named because they contain mostly ionized hydrogen (H+ or HII), HII regions are found throughout the interstellar medium in the Galaxy and in other galaxies.

Where are emission nebulae found?

One of the most famous emission nebulae is the Orion Nebula (M42) located just below Orion's belt. Another common type of emission nebula is a planetary nebula. These objects consist of a central white dwarf star surrounded by clouds of gas released as the original star evolved to the white dwarf phase.

Where are HII regions emission nebulae found quizlet?

These molecules are found in great interstellar clouds that are rich in dust. These great masses of material are called molecular clouds. Much of this material is concentrated in the spiral arms of the Galaxy. HII is a region of interstellar hydrogen that is ionized.

Where are HII regions found?

H II regions are found only in spiral galaxies like the Milky Way and irregular galaxies. They are not seen in elliptical galaxies. In irregular galaxies, they may be dispersed throughout the galaxy, but in spirals they are most abundant within the spiral arms.

What is an emission nebula H II region quizlet?

What is an emission nebula? A glowing region of ionized hydrogen around one or more hot O- and B-type stars. The bright stars at the center of an emission nebula (H II region) are. young O and B stars.

HII Regions and Star Forming Regions (Intro Astronomy lecture 08-04)

What occurs in HII regions of the galaxy?

HII regions are emission nebulae created when young, massive stars ionise nearby gas clouds with high-energy UV radiation. ... In our Galaxy, HII regions follow a distribution pattern similar to that of the molecular clouds from which stars are formed, and are similarly concentrated in the spiral arms of other galaxies.

How is an H II region formed quizlet?

How is an H II region formed? They are hydrogen clouds ionized by the radiation from hot O and B type stars. ... reduction of the apparent brightness of stars by scattering and absorption of their light by intervening interstellar clouds.

What can you find in a planetary nebula?

Planetary nebulae usually contain larger proportions of elements such as carbon, nitrogen and oxygen, and these are recycled into the interstellar medium via these powerful winds.

What is the Orion Nebula quizlet?

The Orion Nebula, also known as M42, is a diffuse nebula situated south of Orion's Belt in the constellation of Orion. It is one of the brightest nebulae, and is visible to the naked eye in the night sky. defining a light year.

Why do nebulae near hot stars look red Why do dust clouds near stars usually look blue?

Nebulae near Hot stars look red because they absorb radiation and they emit a red color. Nebulae near Dust clouds look blue because the dust grain present in them scatters light from the nearest star and it looks blue because of their size. ... List the different ways in which DUST can be detected in interstellar space.

What is the power source of the typical emission nebula quizlet?

The two primary components to an emission nebula are a cloud of hydrogen gas and one or more hot O- or B-type stars. The hot stars emit ultraviolet radiation, which heats the hydrogen gas to the point where electrons are ejected from the hydrogen atoms, thus ionizing the gas.

What is the power source of the typical emission nebula?

An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star.

What is an emission nebula quizlet?

What is an emission nebula? Emits it's on light, with the characteristic emission spectra similar to that of a hot, thin gas. - Emission nebulae are found near hot, luminous stars of spectral types O and B. What is a dark nebula? Something so opaque that it blocks any visible light coming from stars that lie behind it.

Do stars form in emission nebulae?

In some nebulae, stars form out of large clouds of gas and dust; once some stars have formed inside the cloud, their light illuminates the cloud, making it visible to us. These star formation regions are sites of emission and reflection nebulae, like the famous Orion Nebula shown in the picture on the right.

Can planets exist in a nebula?

The answer would be yes. As the planet orbits its star that orbits the center of the galaxy, the planet and its star could enter a nebula and pass through that nebula for thousands or millions of years and then emerge on the other side of the nebula.

How many planetary nebulae are there?

There are believed to be about 20,000 objects called planetary nebulae in the Milky Way Galaxy, each representing gas expelled relatively recently from a central star very late in its evolution. Because of the obscuration of dust in the Galaxy, only about 1,800 planetary nebulae have been cataloged.

What type of objects form planetary nebulae?

In about 5 billion years, when the sun shucks off its outer layers, it will create a beautiful shell of diffuse gas known as a planetary nebula.

How do solar nebulae and planetary nebulae differ?

How do solar nebulae and planetary nebulae differ? Solar nebulae result from the explosions of massive stars, whereas planetary nebulae are ejected by smaller stars.

What is the difference between planetary nebulae emission nebulae reflection nebulae and dark nebulae?

Reflection Nebula - A reflection nebula differs from an emission nebula in does not emit radiation of its own. It is a cloud of dust and gas that reflects the light energy from a nearby star or group of stars. ... Dark Nebula - A dark nebula is a cloud of dust that blocks the light from objects behind it.

Where are the protostars most likely to form?

Stars begin to form from clouds of gas in space. The cold temperatures and high densities (compared to elsewhere in space, but would be considered a vacuum on Earth) of these clouds allow gravity to overcome thermal pressure and start the gravitational collapse that will form a star.

What is an emission nebula also known as an H II region?

H II region, also called diffuse nebula or emission nebula, interstellar matter consisting of ionized hydrogen atoms. The energy that is responsible for ionizing and heating the hydrogen in an emission nebula comes from a central star that has a surface temperature in excess of 20,000 K.

Why do HII regions appear red quizlet?

Why do HII regions appear red? HII regions are composed of completely ionized hydrogen. When the hydrogen captures an electron, light is emitted. The red Balmer hydrogen line is the strongest wavelength emitted.

How can we observe HI regions quizlet?

Astronomers are able to observe hydrogen in HII regions with optical telescopes. How do astronomers observe cold hydrogen clouds (HI regions) that aren't near a star? They use radio telescopes and observe the hydrogen through 21-cm radiation.