The nature of the interstellar medium has attracted the attention of astronomers and scientists for centuries. The term Interstellar Medium was first used by F. Bacon in 1626. Oh, heavens among the stars, they have so much in common with stars, rotation (around the Earth) as well as any other star. Later, natural philosophy of Robert Boyle in 1674 argued: Interstellar region of heaven, as some modern epikureytsy should be empty.
Following the establishment of modern electromagnetic theory of physics, some postulate that the ether is invisible svetonosny medium for the transmission of light waves. They also believed that the air fills interstellar space. Robert Patterson in 1862 wrote: This is the basis of the expiry of vibration or vibrational motions in the air, which fills the interstellar space.
Application of the deep night sky photographic surveys enabled E. Barnard get the first image of dark nebulae, which silhouette stands out against a background of stars the galaxy. However, the first opening of the cold diffuse matter was made by D. Hartmann in 1904 following the discovery of a still in the absorption spectrum of the radiation spectrum of the double stars observed to verify the Doppler effect.
In his historical study of the spectrum of the Delta Orion Gartman studied orbiting companions of Orion Delta and the light coming from stars and realized that some of the light is absorbed on the way to Earth. Hartmann wrote that the line absorption of calcium is very weak, and that some surprise is that the line of calcium at a wavelength of 393.4 nanometers is not moving in a periodic divergent lines of the spectrum, which is present in the spectroscopic-binary stars. The stationary nature of these lines allowed Hartmann suggests that the gas responsible for absorption is not present in the atmosphere of the Delta Orion, but, rather, is outside the star and is situated between the star and the observer. This was the beginning of the study and the study of interstellar medium.
After studies Hartman, Eger in 1919 during a study of the absorption lines at wavelengths 589.0 and 589.6 nanometers in the systems of the Delta Orion and Scorpio beta was detected in the interstellar medium of sodium.
Further investigation of lines "H" and "K" Bilzom calcium (1936) helped discover the double and unbalanced profile spectrum Epsilon and Zeta Orion. It was the first comprehensive study interstellar medium in the constellation of Orion. Asymmetry of profiles of absorption lines was the result of the imposition of numerous absorption lines, each of which corresponded to the atomic transitions (for example, line "K" of calcium) and place in interstellar clouds, each of which has its own beam speed. Since Each cloud is moving at different speeds in interstellar space, as in the direction of the earth, and away from it, it would result in the Doppler effect, the absorption line is shifted, either purple or red side, respectively. This study confirmed that the matter is not distributed uniformly in interstellar space.
Intensive study interstellar matter allowed W. Pickering in 1912, the state, that Interstellar absorption medium, which has shown Kapteyn, absorbs only at certain frequencies, may indicate the presence of gas and gaseous molecules, which wring the Sun and the stars.
In the same year Victor Hess discovered cosmic rays and energetic charged particles that scorer of the Earth. This has allowed some researchers to declare that they also fill an interstellar environment. Norwegian physicist Kristian Birkland in 1913, wrote: The steady development of our point of view zastalyaet assume that all space is filled with free electrons and ions of all kinds. We also tend to assume that all star systems are derived from the charged particles in space. And it does not seem incredible to think that most of the mass of the universe can be found not in the star systems or nebulae, but in the empty Space.
Thorndike in 1930, wrote: It would be terrible to know that there are insurmountable gulf between the stars and full of emptiness. Polar Lights excited by charged particles, which emits our Sun. But if millions of other stars also emit charged particles, which is an immutable fact, the absolute vacuum can not exist in the galaxy.