Hot spots around newborn binary stars

Jan. 2 () –

High-resolution observations with the ALMA telescope from the IRAS 16293-2422 system have revealed localized hot spots in the dusty material of this young star system.

The study led by the Max Planck Institute for Extraterrestrial Physics indicates that it is most likely that are due to local shocks caused by rapid movements of the gas and not to the illumination of the protostars. This suggests that the heat produced in the crashes is an important factor during the early stages of the formation of protostars and the planetary disks that surround them. These shocks could be due to localized accretion of surrounding envelope material or local fragmentation. due to gravitational instabilities.

Astronomers have been studying the area around protostars to better understand not only general star formation, but also the conditions and processes that could have led to the creation of our own Solar System. In particular, nascent stars with a mass close to that of our Sun are very interesting.

Approximately half of the stars similar to the Sun are in the company of other stars, such as the IRAS 16293-2422 binary, discovered by a team of astronomers from the Max Planck Institute for Extraterrestrial Physics (MPE) in 2020.

By taking a closer look at the system with very high-resolution ALMA observations, the team discovered that the system’s two stars are not the only source of heat. “We were able to zoom into the central region and found that hot dust is not correlated with protostar positions,” he says. it’s a statement María José Maureira, the postdoctoral researcher who led the study at MPE.

“Surprisingly, we found localized hot spots, which are probably produced by local shock waves in the gas, like the shock waves produced when a plane travels faster than the speed of sound through the air“.

Such shocks can alter the chemical composition of clouds of gas and dust, releasing molecules previously frozen in sheets of ice around the dust grains. Organic molecules from space are potential precursors to more complex molecules essential for life. Therefore, these shocks can alter the chemical composition and the amount of material that can adhere, modifying the properties of the resulting planetary systems.

“These exciting new observations reveal that our current disk models are incomplete and must include some extra source of heating,” says Jaime Pineda, co-author at MPE. “This will change the way we estimate the dust properties and masses of these young disks.”

The new dust temperature maps agree very well with previous observations of the light emitted by certain molecules.. “These observations have allowed us to reveal the physical conditions and the distribution of complex organic molecules with unprecedented sensitivity and angular resolution,” says Paola Caselli, director of the MPE’s Center for Astrochemical Studies. “This is crucial to understand the chemistry of these molecules and thus fully exploit their diagnostic power not only in this, but also in future observations of similar systems.”

By measuring the temperature around young stars, scientists can learn which molecules are present and how they form. Temperature also influences the amount of dust that can accumulate to form planets. Actually, the ALMA observations were made to determine if the dust grains around the protostars have grown significantly. Since dust growth is the first step toward planet formation, This answers an important question: when do planets form?

“Because this ‘baby’ star system is very bright, we can use it as a laboratory to learn how stars with masses similar to our Sun form,” adds Kadron Silsbee, co-author at the University of Texas. “When we analyzed the size of the dust, we saw that it has probably already grown, but not to the level we expected. It may be related to high hot spot temperatures or misaligned system configuration.” The team is working to obtain further observations and simulate the young binary stellar system on a computer to help answer these new questions.