Free Astronomy Magazine January-February 2025

22 JANUARY-FEBRUARY 2025 ASTRO PUBLISHING ! ence? What’s puz- zling is that the same physics is at work in both,” added Wolff. Located in the sum- mer constellation Lyra, Vega is one of the brightest stars in the northern sky. Vega is legendary because it offered the first evidence for material orbit- ing a star – presum- ably the stuff for making planets – as potential abodes of life. This was first hypothesized by Immanuel Kant in 1775. But it took over 200 years be- fore the first obser- vational evidence was collected in 1984. A puzzling excess of infrared light from warm dust was detected by NASA’s IRAS (Infrared Astronomy Satellite). It was interpreted as a shell or disk of dust extending twice the orbital ra- dius of Pluto from the star. In 2005 NASA’s infrared Spitzer Space Telescope mapped out a ring of dust around Vega. This was fur- ther confirmed by observations using submillimeter telescopes in- cluding Caltech’s Submillimeter Ob- servatory on Mauna Kea, Hawaii, and also the Atacama Large Mil- limeter/submillimeter Array (ALMA) in Chile, and ESA’s (European Space Agency’s) Herschel Space Telescope, but none of these telescopes could see much detail. “The Hubble and Webb observa- tions together provide so much more detail that they are telling us something completely new about the Vega system that nobody knew before,” said Rieke. A Webb view of a 100-billion-mile-wide disk of dust around the star Vega. The disk is remark- ably smooth and shows no evidence of planet formation. [NASA, ESA, CSA, STScI, K. Su (Uni- versity of Arizona), A. Gáspár (University of Arizona)] planet formation, migration, and sometimes destruction. Fully ma- tured stars like Vega have dusty disks enriched by ongoing “bumper car” collisions among orbiting as- teroids and debris from evaporat- ing comets. These are primordial bodies that can survive up to the present 450-million-year age of Vega (our Sun is approximately ten times older than Vega). Dust within our solar system (seen as the Zodiacal light) is also replen- ished by minor bodies ejecting dust at a rate of about 10 tons per sec- ond. This dust is shoved around by planets. This provides a strategy for detecting planets around other stars without seeing them directly – just by witnessing the effects they have on the dust. “Vega continues to be unusual,” said Wolff. “The ar- chitecture of the Vega system is markedly different from our own solar system where giant planets like Jupiter and Saturn are keeping the dust from spreading the way it does with Vega.” For comparison, there is a nearby star, Fomalhaut, which is about the same distance, age and tempera- ture as Vega. But Fomalhaut’s cir- cumstellar architecture is greatly different from Vega’s. Fomalhaut has three nested debris belts. Planets are suggested as shepherd- ing bodies around Fomalhaut that gravitationally constrict the dust into rings, though no planets have been positively identified yet. “Given the physical similarity be- tween the stars of Vega and Foma- lhaut, why does Fomalhaut seem to have been able to form planets and Vega didn’t?” said team member George Rieke of the University of Arizona, a member of the research team. “What’s the difference? Did the circumstellar environment, or the star itself, create that differ-