Why the webb follows neon gas with the aim of new thinking on planet formation.

Scientists are using neon signals to explore the future of one planetary system and the history of another – our own solar system. The James Webb Space Telescope, following up on observations by the retired Spitzer Space Telescope, detected neon in the disk around the young Sun-like star SZ Chamaelontis (SZ Cha). This discovery provides insights into the radiation affecting the disk’s evolution and the potential for planet formation. Differences in neon readings between Spitzer and Webb suggest a change in high-energy radiation, impacting the time available for planets to form.

Differences in neon readings between the Spitzer and Webb telescopes indicate an unprecedented change in high-energy radiation reaching the disk around the young star SZ Chamaelontis (SZ Cha). This change ultimately leads to the disk’s evaporation, reducing the time available for planets to form. Astronomer Catherine Espaillat of Boston University emphasizes the significance of SZ Cha, a T-Tauri star similar to the young Sun, offering insights into the conditions present in the early solar system.

Neon serves as a crucial indicator for scientists, revealing the amount and type of radiation impacting the disk around a star. The Spitzer Space Telescope, in 2008, identified a distinctive neon signature in the disk surrounding the young star SZ Chamaelontis (SZ Cha), deviating from typical T-Tauri disks. The detection of neon III, uncommon in disks bombarded by high-energy X-rays, suggested that SZ Cha’s disk was primarily exposed to ultraviolet (UV) light. This deviation, observed among 50-60 young stellar disks, holds significance for understanding the lifespan and planetary potential of SZ Cha’s disk.

Neon Gas In Protoplanetary Disk.

In a span of 15 years, NASA’s James Webb and Spitzer space telescopes provided contrasting data revealing changes in the disk surrounding the star SZ Chamaeleontis (SZ Cha). In 2008, Spitzer detected significant neon III, making SZ Cha an outlier among similar protoplanetary disks. However, Webb’s 2023 observations showed a neon II to III ratio within typical levels. This discrepancy is crucial as it impacts the potential for planetary system formation. Neon serves as an indicator of the dominant radiation affecting the disk, and variations in neon detections are attributed to the presence of a wind that influences the type of radiation reaching the disk, affecting its evaporation rate.

“Planets are essentially in a race against time to form up in the disk before it evaporates,” explained Thanawuth Thanathibodee of Boston University, another astronomer on the research team. “In computer models of developing systems, extreme ultraviolet radiation allows for 1 million more years of planet formation than if the evaporation is predominately caused by X-rays.” So, SZ Cha was already quite the puzzle when Espaillat’s team returned to study it with Webb, only to find a new surprise: The unusual neon III signature had all but disappeared, indicating the typical dominance of X-ray radiation.

The research team suggests that the variations in neon signatures in the SZ Cha system are likely caused by a changeable wind. When this wind is active, it absorbs ultraviolet (UV) light, allowing X-rays to dominate and impact the surrounding disk. Such winds are typical in systems with newly formed, energetic stars. However, there’s a possibility of observing the system during a period without this wind, characterized by calm conditions. The fact that both the Spitzer and Webb data are of high quality indicates that this observation represents a significant alteration in conditions within the SZ Cha system over just 15 years. Co-author Ardjan Sturm of Leiden University in the Netherlands emphasized the novelty of this finding.

Espaillat’s research team is planning additional observations of SZ Cha using the James Webb Space Telescope, along with other telescopes, in an effort to unravel the mysteries surrounding it. Co-author Caeley Pittman of Boston University emphasizes the importance of studying SZ Cha and similar young systems in multiple wavelengths, such as X-ray and visible light, to uncover the true nature of the observed variability. The team speculates that quiet periods dominated by extreme UV radiation might be common in many young planetary systems, but detecting them has proven challenging.

This dynamic discovery reminds us of the complexity inherent in understanding celestial phenomena, prompting the need for continuous observation and reevaluation. The research has been accepted for publication in Astrophysical Journal Letters.