Using the James Webb Space Telescope, astronomers have made an exciting discovery. They found unexpected high-energy ultraviolet radiation around five young stars, or protostars, in the Ophiuchus star-forming region. This could change how we understand star formation.
Protostars are at the very beginning of their lifespan. They develop from dense patches of gas and dust in molecular clouds. These young stars haven’t yet gathered enough mass to start fusing hydrogen into helium, which is the hallmark of “main sequence” stars.
Iason Skretas from the Max Planck Institute for Radio Astronomy mentioned that they aimed to look closely at these stars that are still forming. As protostars accumulate mass, they also launch jets of material outward.
Traditionally, scientists assumed that young stars wouldn’t produce ultraviolet radiation. However, research team member Agata Karska pointed out that the presence of UV radiation near these protostars was unexpected. This raises important questions about its source: is it coming from inside the stars or from an external source?
To investigate, the team turned the James Webb Space Telescope toward the Ophiuchus molecular cloud, located about 450 light-years from Earth. This area is filled with young, hot “B-type” stars known for strong UV radiation. By studying five protostars positioned at different distances from these massive stars, they focused on emissions from molecular hydrogen, which is abundant in the universe but difficult to detect from Earth.
When outflows from young stars collide with surrounding molecular clouds, shockwaves heat the material and enable molecular hydrogen to emit detectable light. The JWST is perfect for this task, as it can observe these emissions clearly.
The team’s observations confirmed the presence of ultraviolet radiation around the protostars. However, the larger mystery remained: Where was this radiation coming from?
One explanation could be that the radiation originates from processes happening close to the protostars, such as shocks from falling material. Alternatively, it might be emitted along the jets produced by these energetic young stars. The team also considered if neighboring massive stars were shining UV light onto the protostars, but their analysis ruled this out.
Karska emphasized that since they found no variations in the emissions from molecular hydrogen around the stars, it suggested that the UV radiation must be coming from within the protostars themselves.
Going forward, the researchers will continue to study data from JWST, focusing not just on the gas and stars, but also on the dust and ice in the Ophiuchus region. Their goal is to unravel the mystery of the unexplained ultraviolet radiation.
This discovery ties into broader discussions among astronomers about the complexities of star formation. According to a recent survey by the American Astronomical Society, nearly 65% of astrophysics researchers are exploring how external conditions affect star birth. The findings from this recent study could play a significant role in shaping future research in this fascinating field.
For those eager to dive deeper, the team’s research was published in the journal Astronomy & Astrophysics.
