Star formation theories supported by first-of-its-kind discovery

NASA’s NIRCam has directly captured the alignment of bipolar jets in a group of protostellar outflows in Serpen’s North region of the Serpens nebula, finally confirming long-standing theories about star formation.

For the first time, a phenomenon long theorized by astronomers has been directly imaged by James Webb Space Telescope’s Near-Infrared Camera (NIRCam). The groundbreaking image of the Serpens Nebula reveals crucial insights into the process of star formation, specifically showcasing an intriguing group of protostellar outflows.

These outflows are formed when jets of gas, expelled from newborn stars, collide with surrounding gas and dust at high velocities. Unlike the typically varied orientations of such objects within a region, these outflows are remarkably aligned in the same direction, akin to sleet pouring down during a storm.

“Astronomers have long assumed that as clouds collapse to form stars, the stars will tend to spin in the same direction,” said principal investigator Klaus Pontoppidan of NASA’s Jet Propulsion Laboratory in Pasadena, California. “However, this has not been seen so directly before. These aligned, elongated structures are a historical record of the fundamental way that stars are born.”

As an interstellar gas cloud collapses to form a star, it spins more rapidly, forcing the removal of some angular momentum for the gas to continue moving inward. This results in the formation of a disk around the young star, akin to a whirlpool around a drain. Swirling magnetic fields in this inner disk launch material into twin jets, which shoot outwards in opposite directions, perpendicular to the disk.

The Webb image captures these jets as bright, clumpy streaks appearing red, indicative of shockwaves from the jets hitting surrounding gas and dust. The red color signifies the presence of molecular hydrogen and carbon monoxide.

“This area of the Serpens Nebula – Serpens North – only comes into clear view with Webb,” said lead author Joel Green of the Space Telescope Science Institute in Baltimore. “We’re now able to catch these extremely young stars and their outflows, some of which previously appeared as just blobs or were completely invisible in optical wavelengths because of the thick dust surrounding them.”

Several forces can potentially alter the direction of these outflows during a young star’s formative years. One such force is the gravitational interaction between binary stars, causing them to spin around each other and wobble, thus twisting the direction of their outflows over time.

The Serpens Nebula, located 1 300 light-years from Earth, is a young star-forming region, only one or two million years old. It houses a particularly dense cluster of newly forming stars, approximately 100 000 years old, located at the center of the image. Some of these stars will eventually reach the mass of our Sun.

“Webb is a young stellar object-finding machine,” Green said. “In this field, we pick up signposts of every single young star, down to the lowest mass stars.”

“It’s a very complete picture we’re seeing now,” added Pontoppidan.

Throughout the region in the image, filaments, and wisps of different hues represent reflected starlight from still-forming protostars within the cloud. In some areas, dust in front of the reflection appears as an orange, diffuse shade. This region has also been home to other significant discoveries, including the flapping “Bat Shadow,” named after 2020 data from NASA’s Hubble Space Telescope revealed a star’s planet-forming disk to flap or shift. This feature is visible at the center of the Webb image.

The new image and the serendipitous discovery of the aligned objects mark the first step in a broader scientific program. The team will now use Webb’s Near-Infrared Spectrograph (NIRSpec) to investigate the chemical composition of the cloud. They aim to determine how volatile chemicals survive star and planet formation. Volatiles are compounds that sublimate, or transition from a solid directly to a gas, at relatively low temperatures, including water and carbon monoxide. The findings will be compared to the amounts found in protoplanetary disks of similar-type stars.

“At the most basic form, we are all made of matter that came from these volatiles. The majority of water here on Earth originated when the Sun was an infant protostar billions of years ago,” Pontoppidan said. “Looking at the abundance of these critical compounds in protostars just before their protoplanetary disks have formed could help us understand how unique the circumstances were when our own solar system formed.”

These observations were part of General Observer program 1611. The team’s initial results have been accepted in the Astrophysical Journal.

The James Webb Space Telescope, the world’s premier space science observatory, is revolutionizing our understanding of the universe. It is solving mysteries within our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of the universe and our place in it. Webb is an international program led by NASA, with partners ESA (European Space Agency) and CSA (Canadian Space Agency).

References:

¹ First of Its Kind Detection Made in Striking New Webb Image – NASA – June 20, 2024

Featured image: In this image of the Serpens Nebula from NASA’s James Webb Space Telescope, astronomers found a grouping of aligned protostellar outflows within one small region (the top left corner). Serpens is a reflection nebula, which means it’s a cloud of gas and dust that does not create its own light, but instead shines by reflecting the light from stars close to or within the nebula. Credit: NASA, ESA, CSA, K. Pontoppidan (NASA’s Jet Propulsion Laboratory) and J. Green (Space Telescope Science Institute).