Webb telescope spots three debris belts around luminous star Fomalhaut
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[May 09, 2023]
By Will Dunham
WASHINGTON (Reuters) - There has been plenty of excitement in recent
decades about planets detected orbiting various stars beyond our solar
system. But planets provide an incomplete picture of the complex
framework that exists around stars, leaving out components like the
belts of rocky and icy debris orbiting our sun.
Scientists on Monday unveiled observations by the James Webb Space
Telescope showing new details about such features around a luminous star
called Fomalhaut in our own neighborhood of the Milky Way galaxy. These
observations of three concentric dusty rings of debris orbiting
Fomalhaut provide the fullest view to date of such structures outside
our solar system.
Fomalhaut, one of the brightest stars in our night sky and the brightest
in the southern constellation Piscis Austrinus, is located 25 light
years from Earth. A light year is the distance light travels in a year,
5.9 trillion miles (9.5 trillion km).
Astronomers first discovered a single belt of debris around Fomalhaut in
1983. Webb's observations revealed two additional rings nearer the star
- a bright inner one and a narrow intermediate one.
These three belts appear to be populated by objects called planetesimals,
some of which are thought to join together early in a star system's
history to form planets while others remain as debris like asteroids and
comets.
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"Much like our solar system, other planetary systems harbor disks of
asteroids and comets - leftover planetesimals from the epoch of planet
formation - that continuously grind themselves down to micron-sized
particles via collisional interactions," said University of Arizona
astronomer Andras Gaspar, lead author of the study published in the
journal Nature Astronomy.
Fomalhaut is 16 times more luminous than the sun and almost twice as
massive. It is about 440 million years old - less than a tenth the age
of the sun - but is probably nearly halfway through its lifespan.
The three nested belts extend out to 14 billion miles (23 billion km)
from Fomalhaut, about 150 times the distance of Earth to the sun.
While no planets have been discovered yet around Fomalhaut, the
researchers suspect the belts were carved out by gravitational forces
exerted by unseen planets. Our solar system has two such belts - the
main asteroid belt between the rocky planet Mars and the gas giant
Jupiter, and the Kuiper belt beyond the ice giant Neptune.
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![](../images/050923PIX/news_l21.jpg)
This image of the dusty debris disk
surrounding the star Fomalhaut is from the James Webb Space
Telescope's Mid-Infrared Instrument (MIRI), (23 billion kilometers)
from the star. The inner belts were revealed by Webb for the first
time. NASA, ESA, CSA/Handout via REUTERS
![](http://archives.lincolndailynews.com/2017/Jul/22/images/ads/current/rohlfs_lda_072017.png)
The gravitational influence of Jupiter, our solar system's largest
planet, corrals the main asteroid belt. The inner edge of the Kuiper
belt, which is home to dwarf planets Pluto and Eris as well as other
icy bodies of varying sizes, is shaped by the outermost planet
Neptune.
"The secondary gap we see in the system is a strong indication for
the presence of an ice giant in the system," Gaspar said.
The observations from Webb, which was launched in 2021 and began
collecting data last year, were made by its Mid-Infrared Instrument
(MIRI).
"Nearly all of the resolved images of debris disks thus far had been
for the cold, outer regions analogous to the solar system's Kuiper
belt," like Fomalhaut's outer belt, said astronomer and study
co-author Schuyler Wolff of the University of Arizona's Steward
Observatory.
MIRI now can resolve the relatively warmer belts of material
analogous to our main asteroid belt, Wolff said.
Studying these debris belts offers insight into planetary
beginnings.
"Planets form within the primordial disks surrounding young stars.
Understanding this formation process requires a complete
understanding of how these disks form and evolve," Wolff said.
![](http://archives.lincolndailynews.com/2023/May/09/images/ads/current/chicagost_sda_SHG_2023.png)
"There are many open questions about how the dust in these disks
coalesces to form planetary embryos, how the planetary atmospheres
form, et cetera. Debris disks are remnants of this planet formation
process and their structure can provide valuable clues to the
underlying planet population and the dynamical histories," Wolff
added.
(Reporting by Will Dunham, Editing by Rosalba O'Brien)
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