JWST reveals the complex structure of HH 49/50, an outflow from a protostar located at the lower right edge of the image. A very distant spiral galaxy coincidentally lies at the edge of the outflow. Credit: NASA, ESA, CSA, STScI
- Star formation begins in protostars in cold molecular clouds, where gravitational contraction precedes nuclear fusion, and their early evolutionary stages are best characterized through long-wavelength infrared observations.
- The James Webb Space Telescope (JWST) observed Herbig–Haro Object 49/50 (HH 49/50), an outflow originating from a protostar within the nearby Chamaeleon I molecular cloud, a known low-mass star-forming region.
- JWST’s detailed near- and mid-infrared imaging of HH 49/50 elucidated its composition, revealing complex arcs and emissions of hydrogen, carbon monoxide, and energetic dust generated by high-velocity jets from the embedded protostar Cederblad 110 IRS4 impacting the surrounding material.
- These observations solved a former Spitzer Space Telescope puzzle, identifying a feature at the tip of HH 49/50 as a distant spiral galaxy, complementing earlier JWST findings of various frozen molecules in the Chamaeleon I cloud.
the sun produces energy Through nuclear fusion, approximately 600 million tons of hydrogen is converted into helium every second. This process began about 5 billion years ago, and will continue for at least the next 5 billion years.
But the Sun did not come into existence completely. It began its long journey to star formation in a cold molecular cloud. Instability within this dusty gas cloud caused small pockets to shrink. Gravity worked its magic, compressing each clump into a smaller and denser area while simultaneously pulling in more material from around it. The core of the object became hot, and it emitted energy that eventually went out as light and heat. Astronomers call such a developing star a protostar; It will not become a full star unless fusion ignites.
Protostars are extremely difficult to see in visible light because the gas and dust that still surround them obstructs our view. Fortunately, long-wavelength infrared radiation penetrates the massive dust and produces a much clearer picture of this early stage of star formation.
a cosmic whirlwind
It’s no surprise that scientists wanted to turn the powerful infrared eye of the James Webb Space Telescope (JWST) on a particularly bright and nearby protostar and its atmosphere. The researchers targeted Herbig-Haro Object 49/50 (HH 49/50), an outflow from a protostar embedded in the Chamaeleon I molecular cloud complex. This cloud is located in the southern constellation Chamaeleon, about 625 light years from Earth, and represents one of the closest regions churning out low-mass stars similar to the Sun.
HH 49/50 is the visible manifestation of the high-powered jets emitted by the protostar. The jets, which travel at speeds of 60 to 190 miles per second (100 to 300 kilometers per second), create shock waves when they collide with dense material. The hot gas and dust slowly cools, revealing the infrared light JWST detects.
When the retired Spitzer Space Telescope spotted HH 49/50 in 2006, researchers dubbed it a “cosmic tornado” for its twisted, conical shape. JWST observed the object in much greater detail at five near- and mid-infrared wavelengths, capturing hydrogen and carbon monoxide molecules as well as glow from energetic dust. The complex arcs visible within HH 49/50 mimic the waves visible in the wake of a speedboat. They point to the protostar suspected of causing all this mayhem, Cedarblade 110 IRS4, located about 1.5 light-years away in the lower right edge of the image.
Astronomers have previously aimed JWST’s instruments at the Chamaeleon I molecular cloud. In 2023, various researchers took spectral fingerprints of ice in the cloud. They detected frozen water, ammonia, methane and methanol, among others. The discovery offers further evidence that many of the molecules possibly brought to Earth by primitive comets and asteroids may not be unique to our Solar System, but a common feature in other star-forming regions.
a true chameleon
The latest JWST image solves the puzzle that Spitzer’s observations posed. That earlier photo (at left) showed a “star” surrounded by a faint halo at the tip of HH 49/50. Astronomers speculated that it may be physically related to outflows or coincidental alignments.
JWST leaves no doubt. The “star” and its halo are actually the central bulge and spiral arms, respectively, of a distant, face-on spiral galaxy. Thousands of years from now, as HH 49/50’s outflow continues to grow, it may well obscure this distant island universe.
