Tiandi Desert Insulation
Interstellar matter is the matter distributed in interstellar space, but it
includes not only matter, but also interstellar gas, dust, cosmic rays and
interstellar magnetic field. The mass proportion of interstellar matter in
the whole galaxy is not high, about 10% of the mass of stars, but its
volume is far larger than that of stars. In interstellar matter, gas
accounts for about 99%, while dust accounts for 1%. According to the
observation of interstellar matter, it is found that they are mainly
distributed within 1000 light years near galactic plane.
Interstellar gas is mainly composed of hydrogen.
According to the different environment of hydrogen, the composition of
hydrogen is different.
There are atomic hydrogen, ionic hydrogen and molecular hydrogen, and their
distribution in space is very uneven.
The existence of hydrogen ion means that the electrons in the hydrogen atom
have been ionized and escaped the shackles of the nucleus. The
reason why the electrons can leave the nucleus is that it is at a high
temperature or it is influenced by the outside world. The main reason is
there are young massive stars in the original neutral hydrogen gas or near
it. These stars are usually at high temperature, so the energy carried
by the radiation they generate is very high, usually in the ultraviolet
Although dust accounts for 1% of the mass in
interstellar matter, it plays a very important role. The medium needed for
atoms to combine into
molecules is dust particles, so dust is often combined with molecules.Dust
is also studied through its radiation influence on the outside world
and its own radiation. The following two pictures show the observation
images of the "Snake Nebula" in the optical and infrared bands. In the
optical band, an irregularly shaped black area appears in the center. This
area is not really devoid of stars, but there is a gas cloud in front of it,
which contains a lot of dust. The absorption of dust blocks the radiation of
the stars behind it, so it is impossible to see the radiation of the stars
behind it. However, after the dust is irradiated by the starlight of the
stars, their own temperature will rise, so "re-radiation" will be produced.
This "re-radiation" is not in the optical band, but in the infrared band.
Therefore, if you use an infrared telescope to observe the same sky area,
you will see the radiation produced by dust particles from this area.
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