Discovery of Glowing Dark Clouds and Molecules Near Earth

Stars and planets arise from swirling clouds of cosmic gas and dust, primarily composed of hydrogen and other molecular elements. On Monday, astronomers announced the discovery of the closest known cloud to Earth, a vast, crescent-shaped region teeming with potential for star formation.

This cloud, located approximately 300 light-years from our solar system, has been named after EOS, the Greek goddess of dawn. It is the first molecular cloud identified through hydrogen fluorescence, according to Blakeley Burkhart, an astrophysicist at Rutgers University.

“If you observe these clouds in the sky, they’re enormous,” Dr. Burkhart stated. The findings were published in conjunction with a colleague in the Nature Astronomy Journal. She also remarked, “It literally glows in the darkness.”

Investigating clouds like EO, especially regarding their hydrogen content, could reshape astronomers’ understanding of the galactic material available for planet and star formation. This research also provides insights into the rates of formation and destruction of the materials that fuel these processes.

“For the first time, we are observing this hidden reservoir of hydrogen that can create stars,” explained Thavisha Dharmawardena, an astronomer at New York University and co-author of the study. Following the discovery of EOS, astronomers expressed a desire to identify more hydrogen-rich clouds.

Molecular hydrogen, which consists of two hydrogen atoms, is the universe’s most abundant substance. This stellar nursery contains it abundantly. However, detecting these molecules from the ground is challenging because they emit light at wavelengths easily absorbed by the Earth’s atmosphere.

In contrast, carbon monoxide—composed of one carbon atom and one oxygen atom—is simpler to detect. It emits light at longer wavelengths, making it accessible for observation with radio telescopes commonly used to identify star-forming clouds.

EOS eluded detection for a long time due to its unexpected nature and low carbon monoxide levels.

Dr. Burkhart identified the cloud while analyzing data from approximately 20 years earlier from the Far-Ultraviolet Imaging Spectrograph (FIMS), an instrument aboard a Korean satellite. She found molecular hydrogen signatures in areas where she believed no molecular cloud existed and collaborated with Dr. Dharmawardena for deeper investigation.

“At this stage, I was familiar with nearly every molecular cloud by name,” Dr. Dharmawardena noted. “I had no awareness of this particular structure; I couldn’t comprehend it.”

Dr. Dharmawardena confirmed the discovery against the 3D map of interstellar dust in our galaxy, which was developed using data from the now-retired Gaia Space Telescope. “EOS was distinctly outlined and visible,” she commented. “It’s a stunning structure.”

John Black, an astronomer at Sweden’s Chalmers Institute of Technology, lauded the methods used to unveil EOS, though he was not part of the research team.

“It’s remarkable to witness molecular hydrogen firsthand and trace the outline of this cloud,” Dr. Black remarked. He added that, compared to carbon monoxide, hydrogen reveals the “authentic shape and size” of EOS.

Utilizing molecular hydrogen data, astronomers estimated the mass of EO to be about 3,400 times that of our Sun, significantly exceeding the carbon monoxide-based estimate of 20 solar masses.

Dr. Burkhart suggested that similar carbon monoxide measurements may underrepresent the mass of other molecular clouds. She emphasized the significance of this finding in stellar formation, as larger clouds can spawn larger stars.

In a follow-up study, EOS, which remains unreviewed, revealed that the cloud has not produced a star previously. However, the future potential for star formation remains uncertain.

Dr. Burkhart collaborated with a team of astronomers to conceptualize a NASA spacecraft named EOS, which inspired the cloud’s name. This proposed space telescope aims to map molecular hydrogen content in clouds across the galaxy, including its namesake.

Such a mission could enhance our understanding of the potential for more concealed clouds and known stellar clouds to contribute to star and planet formation.

“I genuinely don’t know how stars and planets come into being,” Dr. Burkhart admitted. “By observing molecular hydrogen firsthand, we can gain insights into how the birthplaces of stars form and how they ultimately fade away.”