Science.-Webb deciphers the chemical composition around a protostar – Publimetro México

Madrid, 17 (Europe Press)

A protostar is a newly formed star that is still feeding off an envelope of matter that gave birth to it. These envelopes host chemical reactions that convert simple chemical building blocks into more complex organic molecules, which may be the precursors to the molecules needed for the emergence of life.

Researchers believe that these complex organic molecules are formed in chemical reactions that occur on the surface of the ice grains. When the star heats up the particles, they leave the ice and mix with the gas around them.

“We want to get definitive evidence of these formation pathways,” says Yao-Lun Yang of the RIKEN Star and Planet Formation Laboratory, a member of the team that conducted the analysis. “The Web provides the best opportunity to do this.”

JWST was launched in December 2021, about 1.5 million kilometers from Earth. Yang, along with RIKEN colleagues Yuki Okoda and Nami Sakai and members of the CORINOS team, used data from the telescope’s mid-infrared instrument (MIRI), obtained in July 2022, to study a very young protostar.

When molecules absorb certain frequencies of infrared light, they stretch and bend in different ways depending on their structure. Because each type of molecule absorbs infrared light at a distinct set of frequencies, the infrared spectrum detected by MIRI can identify molecules around the protostar.

Previous surveys of the protostar have identified complex organic molecules in the gas phase, and MIRI provides a much more detailed picture as it can detect organic molecules in the ice, where they are thought to be forming. The results confirm the presence of water ice, carbon dioxide, and silicates present in the dust, along with particles such as ammonia, methane, methanol, formaldehyde, and formic acid. There are also notes of ethanol and acetaldehyde.

Protostars often produce outflows and jets, and this protostar is no exception. MIRI has produced images that reveal the structure of one of the star’s outflows, showing at least four shell-like structures. The outflow contains a mixture of elements including hydrogen, iron, nickel, neon, argon, and sulfur. Some is concentrated in a relatively hot jet moving at about 200 kilometers per second. These outflows are being observed when they are probably only 170 years old, just a blink of an eye in terms of stellar evolution.

All of these findings bode well for the future. “We’re going to start to understand how organic chemistry came about,” Yang says. “We will also discover long-term effects on planetary systems similar to our solar system.”

The work has been published in The Astrophysical Journal Letters.