A Lonely Massive Star Reveals Secrets of Stellar Chemistry
More than 16,000 light-years from Earth, a young, solitary star is revealing rare clues about the chemistry that shapes the birthplaces of massive stars—those more than eight times the mass of our Sun.
Led by Dr. Prasanta Gorai, a team of astrochemists studied the isolated massive star G28.20-0.05, and uncovered a remarkably rich and complex chemical environment (see Figure 1). Using observations from the Atacama Large Millimeter/submillimeter Array (ALMA), a powerful radio telescope made of 66 antennas in the Atacama Desert in Chile, researchers uncovered a mix of molecules and used them as “chemical fingerprints” to learn more about how the star is growing.
Figure 1: Left A detailed picture of the star-forming object G28.2.20-0.05 obtained with ALMA. The white lines show contour levels, highlighting how bright different parts are. The white crosses mark three important spots in the cloud that are rich in molecular species. Right A close-up of the center, showing where different molecular species shine the brightest in the gas.
G28.20-0.05 is a star in the making, also called a “protostar.” Still gathering material from the dense interstellar gas and dust around it, massive stars are rare and short-lived. Because of this, catching them in the act of formation is incredibly difficult. Traditionally, scientists have believed that massive stars only form in large clusters, where many stars grow together, compete for material, and stir up their surroundings. Unlike some others, G28.20-0.05 has formed in isolation, far from the usual crowded star clusters. Therefore, it gives scientists a rare opportunity to observe the chemistry of a star-forming environment without interference from nearby sources.
The team detected more than a dozen complex organic molecules: carbon-based molecules considered the building blocks of life. These include species like methanol and methyl formate, which form either in the gas or on the icy surfaces of dust grains in space. These molecules serve as probes because their relative abundances can tell scientists about the temperature, density, and even the age of the star-forming region.
What makes G28.20-0.05 especially interesting is how its chemical profile compares to that of more crowded star-forming regions. In more “social” settings, protostars tend to show more chaotic chemical signals, likely due to the influence of neighboring stars. But here, the team has found a cleaner, more uniform chemical environment that is still surprisingly rich.
This discovery helps refine how scientists interpret molecular signals from space. By focusing on a single, solitary star, scientists are better equipped to understand the noisy, crowded universe around us.
This article made use of the following publication:
Gorai et al., 2024, The Astrophysical Journal, 960:127 (25pp)Original Author
Dr. Mélisse Bonfand
VICO Postdoctoral Fellow at the University of Virginia
Contributing Editors
Brielle Shope
Editor-in-Chief
Annika Geiger
Senior Editor
