Even Near a Supermassive Black Hole, Stars Enrich the Interstellar Medium

• Astronomers using the James Webb Space Telescope (JWST) have discovered that IRS 3, an asymptotic giant branch (AGB) star near the Milky Way's central supermassive black hole (Sgr A*), continues to produce dust and water despite intense radiation.
• Findings confirm that stars in extreme galactic environments can effectively recycle material into the interstellar medium (ISM).

The Research and IRS 3

• IRS 3 is a 72-million-year-old AGB star with approximately 6 solar masses, located only 0.17 parsecs (0.55 light-years) from Sgr A*.
• The study, led by Florian Peißker of the University of Cologne, utilized JWST's NIRCam and Mid-Infrared Instrument (MIRI) to analyze the star's dusty envelope.
• The star is surrounded by a gaseous cocoon spanning roughly 10,000 astronomical units, exhibiting a temperature gradient from 1200 K near the star to 100 K in outer regions.

Findings and Chemical Composition

• Spectroscopic analysis identified the presence of amorphous silicates, alumina (Al2O3), and, for the first time in such an environment, water (H2O).
• The team calculated a mass loss rate of approximately 20 Earth masses per year—or one Earth mass every 18 days—characteristic of the "superwind phase" of an O-rich AGB star.
• Researchers determined this rate by analyzing the star's bow shock, which provides a measure of ambient ISM ram pressure.

Scientific Significance

• The resilience of these materials demonstrates that molecular material and dust can survive in radiation-dominated zones.
• This research provides key insights into how AGB stars shape the composition of the interstellar medium even in the most extreme regions of the galaxy.