A giant young star, many times the mass of the Sun, along with a cloud of gas and dust surrounding it, fell into the field of view of the Herschel orbiting telescope.
The protostar, which received the astronomical designation RCW 120, is only a few tens of thousands of years old and in which thermonuclear reactions have not yet begun, has a mass 8-10 times the mass of the Sun and is surrounded by a cloud, which contains about 200 times more matter than in Solar system.
If the gas and dust from this cloud continues to fall on the protostar, it could ignite and turn into one of the brightest giant stars in our galaxy - the Milky Way.
“It is the massive stars that control the dynamic and chemical evolution of the galaxy,” says Dr. Annie Zavagno of the Astrophysical Laboratory in Marseille. “Massive stars generate heavy elements like iron and push them into interstellar space. And as they end their lives in a supernova explosion, they fill galactic space with energy."
The existing theories of star formation cannot explain the existence of stellar objects with a mass exceeding the mass of the Sun by more than 10 times. The harsh radiation emitted by such stars should blow away the surrounding clouds of gas and dust, thus limiting their growth. At the same time, astronomers know stars with a mass of 120 or more times greater than the Sun.
By the way, the star RCW 120, like many others, including those with planets, astronomers could have discovered much earlier if they had initially used a more accurate search method.
According to the journal Nature, the Lyman-alpha method that scientists still use to detect galaxies billions of light-years away from Earth is actually only able to find one galaxy in ten!
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Astronomers have suspected this for a long time, but only Matthew Hayes of the University of Geneva and his colleagues, using the equipment of the European Southern Observatory's VLT telescope, were the first to confirm these assumptions with observational data.
“Astronomers have always known that a fraction of the galaxies in Lyman-alpha exploration is missing, but now we have estimates for the first time. The number of missed galaxies is significant,”Hayes said.
To test their hypothesis, scientists studied the same area of the starry sky, where galaxies are located, the light from which travels to the Earth for 10 billion years. Using two of the four eight-meter telescopes that make up the VLT, astronomers estimated the number of galaxies using the standard Lyman-alpha method and from another spectral series, H-alpha, discovered by Swiss Johann Balmer. The radiation corresponding to different lines differs in wavelength.
For the H-alpha line to appear, the electron needs to move between the second level and the levels lying above. Since hydrogen atoms with an electron in the second level are very rare in the interstellar medium, such light can pass almost unhindered through clouds of dust and gas, absorbing most of the radiation corresponding to the Lyman-alpha line.
Therefore, the researchers conclude, the search for galaxies using H-alpha is much more effective than the search using the traditional method. Due to absorption of radiation, approximately nine out of ten galaxies remained unnoticed.
“Now that we know how much light was missing, we can start working on much more accurate representations of the cosmos, better understanding how quickly stars emerged at different times in the life of the universe,” notes another author of the discovery, Miguel Mas-Hesse.
Andrey Kleshnev