In this image of the Serpens Nebula taken with the near-infrared camera (NIRCam) on NASA’s James Webb Space Telescope, astronomers found a group of aligned protostellar outflows within one small region (the upper left corner). In the Webb image, these jets are indicated by bright clumpy streaks that appear red, which are shock waves from the jet hitting surrounding gas and dust. Credit: NASA, ESA, CSA, STScI, Klaus Pontoppidan (NASA-JPL), Joel Green (STScI)
Alignment of bipolar jets confirms theories of star formation
Some of the biggest and most interesting astronomical discoveries have come as a surprise to researchers, even as they explore the best-studied parts of the sky.
Often it is new technology or coincidental timing that leads to these discoveries. In a new study of the Serpent Nebula with NASA‘S James Webb Space Telescopeit’s both.
In one part of the nebula, Webb has turned what previously appeared as fuzzy blobs into bright protostellar outflows. And to the surprise of the researchers, it turns out that these outflows are aligned, indicating that we have discovered this region at a unique time in its history and providing information about the basics of how stars are born.
First detection of its kind made in striking new image from the Webb Space Telescope
For the first time, a phenomenon that astronomers long hoped could be directly imaged has been captured by the Near-Infrared Camera (NIRCam) on NASA’s James Webb Space Telescope. In this stunning image of the Serpent Nebula, the discovery lies in the northern region (visible above left) of this young, nearby star-forming region.
Astronomers have discovered an intriguing group of protostellar outflows, which form when jets of gas spewing from newborn stars collide at high speed with nearby gas and dust. Usually these objects have different orientations within one area. Here, however, they run in the same direction and to the same extent, like sleet during a storm.
The discovery of these aligned objects, made possible by Webb’s exquisite spatial resolution and sensitivity in near-infrared wavelengths, provides information about the basic principles of how stars are born.
“Astronomers have long believed that as clouds collapse to form stars, the stars will tend to spin in the same direction,” said lead researcher Klaus Pontoppidan of NASA’s Jet Propulsion Laboratory in Pasadena, California. “However, this has never been seen so directly before. These aligned, elongated structures provide a historical record of the fundamental way stars are born.”
This image from NASA’s James Webb Space Telescope shows part of the Serpens Nebula, where astronomers discovered a group of aligned protostellar outflows. These jets are indicated by bright, clumpy streaks that appear red, which are shock waves from the jet hitting surrounding gas and dust. Here the red color represents the presence of molecular hydrogen and carbon monoxide. Credit: NASA, ESA, CSA, STScI, Klaus Pontoppidan (NASA-JPL), Joel Green (STScI)
The mechanisms of star formation
How does the alignment of the stellar jets relate to the star’s rotation? When an interstellar gas cloud collides with itself and forms a star, it spins faster. The only way for the gas to continue moving in is to remove some of the spin (known as angular momentum). A disk of material forms around the young star to transport material downward, like a vortex around a drain. The swirling magnetic fields in the inner disk launch some of the material into twin jets that shoot out in opposite directions, perpendicular to the material disk.
In the Webb image, these jets are indicated by bright clumpy streaks that appear red, which are shock waves from the jet hitting surrounding gas and dust. Here the red color represents the presence of molecular hydrogen and carbon monoxide.
This image shows the center of the Serpent Nebula as seen by the Near-Infrared Camera (NIRCam) on NASA’s James Webb Space Telescope. In this image, filaments and strings of different hues throughout the region represent reflected starlight from still-forming protostars in the cloud. In some places there is dust for that reflection, which appears here with an orange, diffuse tint. Credit: NASA, ESA, CSA, STScI, Klaus Pontoppidan (NASA-JPL), Joel Green (STScI)
Improved imaging techniques
“This region of the Serpens Nebula – Serpens North – really comes into focus with Webb,” said lead author Joel Green of the Space Telescope Science Institute in Baltimore. “We are now able to capture these extremely young stars and their outflows, some of which previously looked like just blobs or were completely invisible in optical wavelengths due to the thick dust surrounding them.”
Astronomers say there are a number of forces that could potentially change the direction of the outflow during this period of a young star’s life. One way is when binary stars orbit each other and wobble in orientation, changing the direction of the outflow over time.
This image of the Serpent Nebula, captured by Webbs Near-Infrared Camera (NIRCam), shows compass arrows, scale bar and color key for reference.
The north and east compass arrows indicate the orientation of the image in the sky. Note that the relationship between north and east in the sky (as seen from below) is reversed relative to the directional arrows on a map of the ground (as seen from above).
The scale bar is indicated in light years, which is the distance light travels in one Earth year. One light year is equal to approximately 5.88 trillion miles or 9.46 trillion kilometers.
This image shows invisible near-infrared wavelengths of light translated into colors of visible light. The color key shows which NIRCam filters were used to collect the light. The color of each filter name is the visible light color used to represent the infrared light passing through that filter.
Credit: NASA, ESA, CSA, STScI, Klaus Pontoppidan (NASA-JPL), Joel Green (STScI)
Stars of the Serpent Nebula
The Serpent Nebula, located 1,300 light-years from Earth, is only one to two million years old, which is very young cosmically. It is also home to a particularly dense cluster of newly formed stars (~100,000 years old), seen in the center of this image. Some of these stars will eventually grow to the mass of our Sun.
“Webb is a young, great object search engine,” Green said. “In this field we pick up signposts from every young star, down to the lowest-mass stars.”
“It’s a very complete picture that we see now,” Pontoppidan added.
Throughout the region in this image, filaments and strings of varying hues represent reflected starlight from still-forming protostars in the cloud. In some places there is dust for that reflection, which appears here with an orange, diffuse tint.
This region has been home to other accidental discoveries, including the fluttering ‘Bat Shadow,’ which was named when 2020 data from NASA’s Hubble Space Telescope revealed that a star’s planet-forming disk was flapping or shifting. This feature is visible in the center of the Webb image.
Path to future research
The new image and the accidental discovery of the aligned objects is actually just the first step in this scientific program. The team will now use Webb’s NIRSpec (Near-Infrared Spectrograph) to investigate the chemical composition of the cloud.
The astronomers are interested in determining how volatile chemicals survive the formation of stars and planets. Volatile substances are compounds that sublimate, or change directly from a solid to a gas, at a relatively low temperature, including water and carbon monoxide. They then compare their findings with the quantities found in protoplanetary disks of stars of the same type.
“At its most basic level, we are all made of matter that comes from these volatiles. Most of the water here on Earth was formed when the sun was still a young protostar billions of years ago,” says Pontoppidan. “Looking at the abundance of these crucial compounds in protostars just before their protoplanetary disks formed can help us understand how unique the conditions were when our own solar system formed.”
These observations were made as part of the General Observer program 1611. The team’s initial results have been accepted for publication in the Astrophysical Journal.
The James Webb Space Telescope (JWST) is a large space-based observatory launched in December 2021. It is the scientific successor to the Hubble Space Telescope. Equipped with a 6.5 meter main mirror, JWST specializes in observing the universe in the infrared spectrum, allowing it to see further back in time than ever before. This capability allows the telescope to study the formation of the first galaxies, the evolution of stars and planetary systems, and the atmospheres of distant exoplanets. Positioned at the second Lagrange point (L2), approximately 1.5 million kilometers from Earth, JWST is designed to provide unprecedented resolutions and sensitivities, opening new windows to the cosmos.