Astronomers discover power source for giant stars

A group of astronomers using a telescope ALMA in Chile has established, how massive stars form when their own powerful radiation should destroy the incoming matter.

Astronomers have discovered, that huge cosmic gas flows act as interstellar highways, redirecting matter, directly to young stars. Stars with masses exceeding the solar mass at least 8 times, are classified as massive. Such stars form quickly, releasing powerful stellar wind and radiation. Under normal circumstances, these forces would have to blow away matter, preventing stars from becoming gigantic. However, something serves as fuel for these stars, allowing them to rapidly gain mass. 

For a long time, scientists have agreed, that accretion disks of dust and gas around stars provide the necessary material for their formation. However, a new study by an international group of scientists, including scientists from Kyoto and Tokyo universities, gives a different answer. 

To test this hypothesis, astronomers needed to conduct careful observations of the areas, where stars form. Meanwhile, the birthplaces of supermassive stars are farther away than smaller stars. Astronomers used the Large Telescope in the Chilean Atacama Desert to make the observation, consisting of dozens of antennas capable of detecting weak radiation from dust and molecules in the millimeter wavelength range.

Accuracy ALMA allowed astronomers to observe, how a young star receives matter from two separate streams. One of these streams was directly related to the central region of the star and showed a pattern of velocity consistent with rotation and possibly falling. This indicates, that the flow quickly carries enough material to withstand the feedback of the young star, forming a dense region around its core.

The researchers expected to see a dust disk or torus with a size of several hundred thousand AU, but they did not expect the spiral arms to be so close to the central source. According to Fernando Olguin, streamers were discovered, that fed what was believed to be an accretion disk at the time. However, scientists were surprised to find, that the disk either did not exist at all or was extremely small. 

These results show that, regardless of the presence of a disk around the central star, streamers can transport large volumes of gas to feed star formation regions, even in the presence of feedback from the central star.

The team plans to expand their research by studying other regions to find out if this is a common type of accretion that leads to formation of massive stars. They also plan to study the gas near the star to determine whether the presence of small disks can be confirmed or denied.

The results of the study are published in the journal Science Advances

Source: SciTechDaily