James Webb Telescope Discovers Ultraviolet Radiation in Star Nursery

Using the James Webb Space Telescope, astronomers have detected unexpected high-energy ultraviolet radiation around five infant stars, known as protostars, in the Ophiuchus star birthing region. This finding could significantly alter existing models of star formation.

Protostars are in the early stages of their lifetimes, formed from the collapse of dense patches of gas and dust in molecular clouds. They are surrounded by material from which they gather mass until they can initiate hydrogen fusion in their cores.

Research team member Iason Skretas from the Max Planck Institute for Radio Astronomy emphasized the importance of understanding these young stars, stating they launch jets as they accrete mass. The team found that to comprehend these powerful outflows, ultraviolet radiation must be considered.

Agata Karska from the Center for Modern Inter-disciplinary Technologies at Nicolaus Copernicus University remarked that this ultraviolet radiation was unexpected, as young stars cannot produce radiation themselves.

This has led the team to investigate the origin of this UV radiation. The Ophiuchus molecular cloud, located approximately 450 light-years from Earth, is home to many young B-type stars that emit strong ultraviolet radiation.

The team conducted their study using the James Webb Space Telescope's Mid-Infrared Instrument, focusing on emissions from molecular hydrogen, the universe's most abundant molecule. While molecular hydrogen is difficult to detect from Earth due to atmospheric interference, the JWST's capabilities allow for its identification in space.

Researchers noted that shockwaves created by outflows from young stars can heat the surrounding matter, causing molecular hydrogen to emit detectable signals. The JWST observations confirmed the presence of ultraviolet radiation around the protostars in Ophiuchus, but the source remains unclear.

Possible internal sources could include shocks from material falling onto the protostars or jets from the stars themselves. Alternatively, external massive stars could be shining UV light onto nearby protostars.

The research team examined the distances of surrounding stars and the dust’s ability to absorb and re-emit UV radiation. Skretas explained that analysis showed significant variations in external UV conditions among the protostars, but the expected differences in molecular emissions were not observed.

Consequently, Karska stated they could confidently conclude that the observed ultraviolet radiation is internally generated around the protostars, affecting the molecular lines observed. Researchers will continue analyzing JWST data to explore the gas, dust, and ice in the Ophiuchus region to better understand this mysterious ultraviolet radiation.