Even in our articles we have often talked about the interstellar medium, it is clear that the reason for this is that it is the rare substance composed of gas and dust that we find inside a galaxy among the different stars that make it up, and therefore it is present everywhere in the universe.
Discovery of the interstellar medium
However, consider that it was only discovered at the end of the 19th century, in fact before it was thought that interstellar space was essentially empty, then In the early 20th century, more precisely in 1904, German astronomer Johannes Hartmann discovered that dying stars released a host of atoms and molecules into space. : interstellar gas, which is then found at the base of formation of new stars and planets.
At this point, it was evident that what had until then looked like empty space was actually rich in matter that we could never have noticed.
after a few decades, In 1930, it was the Swiss Robert Trompler’s turn to discover interstellar dustmeaning that it is this collection of gases and matter that turns distant stars red.
The evidence for the existence of some kind of matter in galaxies was entirely empirical. In reality, Astronomers have noticed a certain influence of the interstellar medium on observations The extinction of the light emitted by the star whose intensity is diminished due to the processes of refraction and absorption by the medium itself.
Light absorption by the interstellar medium
It is precisely the study of the different absorption bands, which are not attributed to a star, that has provided us with a great deal of information about the density and velocity of the gases that make up the interstellar medium. In reality, The composition of this gas can also be very different from one galaxy to another, for example in young galaxies, spiral galaxies like our own Milky Way, they are more abundantin the lenticular it is little, and in the oval it is almost completely absent.
The type of absorption thus recorded indicates the presence of large complex particles, but doubts remain about their exact location and as to the particular substance causing the black bands in the light spectrum.
It is clear that as the technology at our disposal has become more advanced, tremendous progress has been made in understanding the chemical composition and distribution of this mysterious substance. In reality, Significant progress has been made in this area only recently Thanks to the technological development in the field of infrared, millimeter and sub-millimeter devices, that is, in the spectral ranges where these regions of space are best tracked.
However, there are still many mysteries regarding the interstellar medium which can only be resolved by further studies.
