The Interstellar Medium (ISM) is the stuff between the stars from which stars form. Although this material typically has a low density, there are some areas known as nebulae where it can be easily seen. Dark Nebulae appear <1> since they are obscuring light from distant stars. Relection nebulae appear <2> due to preferential scattering. The small dust grains scatter blue light much better than red light. The third type Emission Nebulae are also known as <3> and appear <4>. This occurs because nearby hot stars are producing <5> radiation which ionizes the hydrogen -- knocks the hydrogen electron free from the proton. These electrons will float around for a while but will eventually recombine with another proton. When that happens some of these electrons will travel through level <6> on their way to ground state producing either a red, blue, or violet photon.
However, in most parts of the sky we must look for much more subtle evidence of the existence of the interstellar medium. Three types of subtle evidence exist known as interstellar extinction, interstellar reddening, and interstellar absorption. Interstellar absorption lines indicate the presence of the ISM because they are <7> than stellar absorption lines.
The ISM consists of 4 distinct components: HI Clouds, Intercloud Medium, Dark Molecular Clouds, and Coronal Gas. It is thought that stars typically form from the <8>.
@ qu.1.1.blank.1=black,pink,blue,green,paisley@ qu.1.1.blank.2=blue,black,pink,green,paisley@ qu.1.1.blank.3=HII regions,HI regions,HIII regions,HeII regions,HeI regions @ qu.1.1.blank.4=pink,black,blue,green,paisley@ qu.1.1.blank.5=UV,IR,X-Ray,Microwave,Gamma-Ray@ qu.1.1.blank.6=2,3,4,5@ qu.1.1.blank.7=thinner,thicker,darker,lighter,shifted more,shifted less@ qu.1.1.blank.8=Dark Molecular Clouds,Coronal Gas,HI Clouds,Intercloud Medium@ qu.1.1.grader.1=menu@ qu.1.1.grader.2=menu@ qu.1.1.grader.3=menu@ qu.1.1.grader.4=menu@ qu.1.1.grader.5=menu@ qu.1.1.grader.6=menu@ qu.1.1.grader.7=menu@ qu.1.1.grader.8=menu@ qu.1.2.mode=Blanks@ qu.1.2.editing=useHTML@ qu.1.2.name=Interstellar Medium B@ qu.1.2.question=The Interstellar Medium (ISM) is the stuff between the stars from which stars form. Although this material typically has a low density, there are some areas known as nebulae where it can be easily seen. Relection nebulae appear <1> due to preferential scattering. The small dust grains scatter blue light much better than red light. Dark Nebulae appear <2> since they are obscuring light from distant stars. The third type Emission Nebulae are also known as <3> and appear <4>. This occurs because nearby hot stars are producing <5> radiation which ionizes the hydrogen -- knocks the hydrogen electron free from the proton. These electrons will float around for a while but will eventually recombine with another proton. When that happens some of these electrons will travel through level <6> on their way to ground state producing either a red, blue, or violet photon.
However, in most parts of the sky we must look for much more subtle evidence of the existence of the interstellar medium. Three types of subtle evidence exist known as interstellar extinction, interstellar reddening, and interstellar absorption. Interstellar extinction is apparent because stars appear <7> than would be expected.
The ISM consists of 4 distinct components: HI Clouds, Intercloud Medium, Dark Molecular Clouds, and Coronal Gas. It is thought that supernovae are responsible for producing the <8>.
@ qu.1.2.blank.1=blue,black,pink,green,paisley@ qu.1.2.blank.2=black,pink,blue,green,paisley@ qu.1.2.blank.3=HII regions,HI regions,HIII regions,HeII regions,HeI regions @ qu.1.2.blank.4=pink,black,blue,green,paisley@ qu.1.2.blank.5=UV,IR,X-Ray,Microwave,Gamma-Ray@ qu.1.2.blank.6=2,3,4,5@ qu.1.2.blank.7=dimmer,brighter,redder,bluer@ qu.1.2.blank.8=Coronal Gas,Dark Molecular Clouds,HI Clouds,Intercloud Medium@ qu.1.2.grader.1=menu@ qu.1.2.grader.2=menu@ qu.1.2.grader.3=menu@ qu.1.2.grader.4=menu@ qu.1.2.grader.5=menu@ qu.1.2.grader.6=menu@ qu.1.2.grader.7=menu@ qu.1.2.grader.8=menu@ qu.1.3.mode=Blanks@ qu.1.3.editing=useHTML@ qu.1.3.name=Interstellar Medium C@ qu.1.3.question=The Interstellar Medium (ISM) is the stuff between the stars from which stars form. Although this material typically has a low density, there are some areas known as nebulae where it can be easily seen. Dark Nebulae appear <1> since they are obscuring light from distant stars. Relection nebulae appear <2> due to preferential scattering. The small dust grains scatter blue light much better than red light. The third type Emission Nebulae appear <3> and are also known as <4>. They occur because nearby hot stars are producing <5> radiation which ionizes the hydrogen -- knocks the hydrogen electron free from the proton. These electrons will float around for a while but will eventually recombine with another proton. When that happens some of these electrons will travel through level <6> on their way to ground state producing either a red, blue, or violet photon.
However, in most parts of the sky we must look for much more subtle evidence of the existence of the interstellar medium. Three types of subtle evidence exist known as interstellar extinction, interstellar reddening, and interstellar absorption. Interstellar reddening manifests itself in the presence of the spectra that are <7> than expected.
The ISM consists of 4 distinct components: HI Clouds, Intercloud Medium, Dark Molecular Clouds, and Coronal Gas. It is thought that supernovae are responsible for producing the <8>.
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