The James Webb Space Telescope resolves the glow of warm dust in a disk halo around Vega, on 23 … [+]
There is no evidence of giant planets around Vega, one of the brightest, most famous and most important stars in the night sky, according to a new study. Using the Hubble and James Webb space telescopes, a team of astronomers at the University of Arizona, Tucson, studied a debris disk about 100 billion miles in diameter around the iconic star. They discovered a perfect circle, without breaks, meaning no planets. For astronomers, this is extremely strange.
Vega: ‘Uniquely Quiet’ Disc
Just 25 light-years from the solar system, Vega is 455 million years old, one-tenth the age of our sun, but 40 times brighter. Its perfectly circular disk makes Vega unique—and confusing.
“The Vega disc is smooth, ridiculously smooth,” said Andras Gáspár of the University of Arizona and a member of the research team. “It’s a mysterious system because it’s unlike any other circumstellar disk we’ve seen.” Circumstellar disks are found only around young stars. Also known as protoplanetary disks, they contain dust and debris that lead to planet formation.
Vega has been the subject of many studies. In 1850, it became the first star other than the sun to be photographed, and 22 years later it was the target for the first spectrographic image. In 2021, researchers published convincing evidence of a “hot Neptune” exoplanet around Vega after a 10-year study, but this new research using the Webb telescope improves on that.
A false-color Hubble Space Telescope view of a 100-billion-mile-wide disk of dust around summer … [+]
Vega: Rethinking How Planets Form
Vega was the source of the alien signal in the film CONTACT. It is also the star by which the brightness of all other celestial objects is measured; Vega’s magnitude—its apparent brightness in the night sky—is traditionally estimated as zero.
However, the softness of Vega’s disk is confusing to astronomers because it means that the composition of its system is different from the solar system. “It’s making us rethink the range and variety among exoplanet systems,” said Kate Su of the University of Arizona, lead author of a paper presenting Webb’s findings published in The Astrophysical Journal. Su was part of a team that in 2013 discovered what appeared to be a large asteroid belt around Vega, which hinted at the presence of planets.
This image of the dusty debris disk surrounding the young star Fomalhaut is from Webb’s Mid-Infrared … [+]
Vega vs. Fomalhaut
A Vega-like star called Fomalhaut — which is also 25 light-years away, twice the mass of the Sun, and about 440 million years old — has three debris belts and most likely many planets. Planetary scientists cannot tell the difference between Vega and Fomalhaut.
“What’s strange is that the same physics is at work in both,” said Schuyler Wolff of the University of Arizona team, lead author of a paper presenting Hubble’s findings published in The Astrophysical Journal. “Did the circumstellar environment create that change, or the star itself?”
The night sky on November 1, 2024, as seen from the Northern Hemisphere.
Vega: Let’s see tonight
Vega in the constellation Lyra may be known as a summer star, but it’s easy to see now. Look west just after dark and you’ll see it shining high in the sky. It is currently the lowest star in a famous asterism, the Summer Triangle, whose three corners are Deneb in Cygnus, bright Vega, and Altair in Aquila. The Milky Way flows through it.
Vega is also a “North Star” in the past and future. The precession of the Earth causes the pole stars to change; as it rotates on its axis, a slight wobble causes that axis to trace a 47° circle to the star every 25,800 years.
For now, she points to Polaris. Vega was the “North Star” in 12,000 BC and will be again around 13,700 AD.
I wish you clear skies and open eyes.