Herschel links star formation to sonic booms

The Herschel satellite European Space Agency (ESA, for its acronym in English) has found that the interstellar clouds closer to Earth contain gaseous filament networks. These filaments have a width similar, suggesting that could be the result of sonic booms in the Milky Way. The satellite also observed that in the densest parts of these filaments are the youngest stars.

Dense filaments of gas in IC5146

Other satellites have observed such filaments in interstellar clouds before, but lacked the resolution needed to determine its width. The ESA's Herschel satellite has shown that all have a similar thickness, regardless of length or density.

The study, by scientists at the Research Institute of the Fundamental Laws of the Universe (IRFU, for its acronym in French) Paris-Saclay (France), was based on analysis of 90 filaments. All had a thickness of about 0.3 light years, about 20,000 times the distance between the Sun and Earth.

After comparing these observations with mathematical models, the authors concluded that these filaments may arise from the dissipation of shock waves in the interior of interstellar clouds. These waves, slightly supersonic, may result from the large amount of turbulent energy is expelled into interstellar space when stars explode. According to research, would travel across the galaxy and its path, compress the gas in it in dense filaments.

Understanding how stars form

Interstellar clouds are very cold, with temperatures about 10 degrees Kelvin above absolute zero. This feature makes the speed of sound inside (shock wave) is spatially slow: about 0.2 km / s, compared with 0.34 km / s which reaches the Earth's atmosphere at sea level.

These shock waves equivalent to the sonic booms, the researchers said, they lose energy while traveling through the clouds, leaving behind a compressed gas filament before dissipating.

"There is direct evidence, but indicates there may be a relationship between the turbulence of the interstellar material and the formation of filaments, which constitute a strong constraint on theories of star formation," explains Philippe Andre, one of the authors the study and researcher at the Laboratory AIM-Saclay IRFU Paris (France). The team has established this comparison through the study of clouds IC5146, Aquila and Polaris.

Herschel has also shown that in the densest parts of the filaments are the youngest stars, after detecting more than one hundred of new generation in a filament that extends through the region of Aquila.

"Thanks to Herschel, finally we are able to observe how stars form inside some of these filaments, as if they were rosary beads," he says Goran Pilbratt, one of the authors of the study and Herschel Project Scientist for ESA.

Source: European Space Agency