'Shockingly bright' carbon monoxide detected in supernova remnant

Supernova observations from the James Webb Space Telescope (JWST) just opened doors to an amazing spectacle of the universe. Experts at the SETI Institute have revealed new details about the youngest known core-collapse supernova in the Milky Way, known as Cassiopeia A.

The team behind this study is reshaping our understanding of the intricate processes involved in the formation and destruction of molecules and dust within supernova remnants.

This remarkable discovery not only provides new insights into the life cycle of stars but also enhances our knowledge of the cosmic elements that contribute to the complexity and diversity of the universe.

Probing a supernova with JWST

The most unexpected aspect of these observations is the vibrant carbon monoxide (CO) emission captured by JWST’s near-infrared imaging and spectroscopy (full image). The study authors described the CO emission as “shockingly bright.”

“It is remarkable to see how bright the carbon monoxide emission detected in JWST NIR imaging and spectroscopy, showing a few tens of sinusoidal patterns of CO fundamental rovibrational lines,” said Dr. Jeohghee Rho, a research scientist at the SETI Institute who led the research. “The patterns look like they were artificially generated.”

The findings from this research touch on three key areas of Cassiopeia A. The team explored the molecular formation, detailed spectroscopy, and temperature indications of the supernova remnant.

Chemistry of supernova remnants

The observations indicate an abundant presence of CO gas in the outer layers of the supernova, far exceeding the amount of argon gas detected.

This significant presence of CO molecules in the supernova’s outermost regions is a remarkable discovery, hinting at previously unknown processes at play.

“To see such hot CO in a young supernova remnant is truly remarkable and indicates that CO formation is still happening thousands of years after the explosion,” said Professor Chris Ashall of Virginia Tech.

The abundance of carbon monoxide implies a fascinating form of molecular rebirth — the CO molecules are potentially forming anew after the reverse shock of the supernova explosion.

This reverse shock, which occurs when the explosion’s blast wave reflects back upon itself, creates conditions that may facilitate the reformation of these molecules.

The idea that CO can reassemble in such a turbulent and high-energy environment challenges previous assumptions about the resilience and dynamics of molecular structures in supernova remnants.

Furthermore, these molecules might have played a crucial role in preserving the dust within the ejecta, contributing to our understanding of cooling and dust formation after a supernova blast.

A new perspective on element formation

The researchers also noted significant differences in the formation of elements within two distinct areas of Cassiopeia A.

Both regions showed strong CO gas signals and various ionized elements like argon, silicon, calcium, and magnesium.

This variance offers a unique glimpse into the high velocity of the CO molecules and their fundamental rovibrational lines, which represent transitions involving changes in both vibrational and rotational states.

Based on CO gas emissions, the team was able to make an educated guess about the temperature of the supernova – a figure close to 1,080 degrees Kelvin.

In addition, high rotational lines indicated the presence of a hotter component, suggesting that CO formation and reformation could be occurring simultaneously.

Extremely hot gas in Cassiopeia A

Supernovae, like the one that formed Cassiopeia A, are celestial explosions that mark the end of a high mass star’s life. This happens when the nuclear fuel that powered the star gets depleted, causing the star to collapse under its own gravity.

The aftermath is a cosmic spectacle – the star’s outer shell is violently shot into space, outshining an entire galaxy.

Manifestations of extremely hot CO in a young supernova remnant are truly extraordinary, hinting at the continuous formation of CO long after the initial explosion.

The power of the JWST

This breakthrough was achieved by harnessing JWST’s Near-Infrared Camera Instrument (NIRCam), the Mid-Infrared Instrument (MIRI), and detailed Near-Infrared Spectrograph (NIRSpec)-Integral Field Units (IFU) spectroscopy.

The collaborative effort between the SETI Institute and Seoul National University enabled the team to chart out the complex structures of synchrotron radiation, argon-rich ejecta, and CO molecules within Cassiopeia A (Cas A). The research highlights the true potential of the James Webb Space Telescope.

The precise role of supernovae in dust formation in the early universe remains an open debate. Future observations and research, driven by the powerful capabilities of JWST, will continue to unveil the enigmas of cosmic dust and molecular formation.

The study is published in the journal The Astrophysical Journal Letters.

Image Credit: NASA, ESA, CSA, D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (UGent), J. DePasquale (STScI)

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