There is no clear evidence that one or more large exoplanets are punching through the frontal debris disk surrounding Vega, one of the brightest stars in the night sky.
Webb used the Mid-Infrared Instrument (MIRI) to obtain images of the circumstellar disk around Vega. Image credits: NASA / ESA / CSA / STScI / S. Wolff, University of Arizona / K. Su, University of Arizona / A. Gáspár, University of Arizona.
Vega is a young, massive star located about 25 light-years away in the constellation Lyra.
This star is classified as type A. This is the name of stars that tend to be larger, younger, and rotate much faster than the Sun.
Vega, also known as Alpharilla, Gliese 721, and HD 172167, is 455 million years old and has a mass equal to two solar masses.
It rotates around its axis every 16 hours. This is much faster than the Sun, which has a rotation period measured in 27 Earth days.
Vega is legendary because it provided the first evidence of matter orbiting a star.
this was the first made a hypothesis However, it took more than 200 years before the first observational evidence was collected in 1984.
A mysterious excess of infrared radiation from warm dust has been detected by NASA's Infrared Astronomy Satellite (IRAS). It was interpreted to be a shell or disk of dust extending from the star to twice Pluto's orbital radius.
In the new study, astronomers analyzed images of Vega's debris disk taken by the NASA/ESA Hubble Space Telescope and the NASA/ESA/CSA James Webb Space Telescope.
“Vega was one of the first typical planetary debris disks to be discovered,” Dr. Kate Hsu of the University of Arizona and colleagues said in their paper. paper Introducing the results of a web survey.
“This opens up a wide field of research, which is now being used to identify relatively low-mass exoplanets that are unreachable with other discovery techniques, as well as to reveal detailed properties of small bodies in other planetary systems. It is used in
“Vega continues to be an anomaly,” added Dr. Schuyler Wolf, an astronomer at the University of Arizona and lead author of the paper. paper Introducing Hubble's discoveries.
“The structure of the Vega system is markedly different from our solar system, where giant planets like Jupiter and Saturn prevent dust from dispersing like Vega.”
“For comparison, there is a nearby star called Fomalhaut, which is about the same distance, age, and temperature as Vega.”
“However, Fomalhaut's circumstellar structure is very different from Vega's. Fomalhaut has three nested debris belts.”
“Exoplanets have been suggested to be bodies that guide the dust around Fomalhaut, which gravitationally compresses it into a ring, but no planets have yet been positively identified.”
“Given the physical similarities between Vega and Fomalhaut's stars, why does Fomalhat appear to be able to form planets, but Vega not?” George Rieke, also of the University of Arizona The doctor said:
“What's the difference? Did the circumstellar environment, or the star itself, make the difference? What's puzzling is that the same physics is at work in both,” Wolff added.
Hubble used the Space Telescope Imaging Spectrograph (STIS) to obtain this image of the circumstellar disk around Vega. Image credits: NASA / ESA / CSA / STScI / S. Wolff, University of Arizona / K. Su, University of Arizona / A. Gáspár, University of Arizona.
Webb observed the infrared glow from a disk of sand-sized particles swirling around a scorching blue-white star that is 40 times brighter than the Sun.
Hubble captures the disk's outer halo, which contains smoke-sized particles that reflect starlight.
The distribution of dust within Vega's debris disk is layered. This is because the pressure of the star's light pushes smaller particles out faster than larger ones.
“Between the Hubble and Webb telescopes, we get a very clear view of Vega,” said Dr. András Gaspard, an astronomer at the University of Arizona and co-author of both papers.
“This is a mysterious system because it is unlike any other circumstellar disk we have observed.”
“Vega discs are smooth. Incredibly smooth.”
The Vega disk has a subtle gap about 60 AU (astronomical units) from the star (twice the distance of Neptune from the Sun), but otherwise it is very smooth the entire time until it disappears into the star's glare. is.
This indicates that there are no planets, at least up to the mass of Neptune, orbiting large orbits like our solar system.
“We are looking in detail at how much diversity there is in the circumstellar disk and how that diversity is tied to the underlying planetary system,” Dr. Hsu said.
“Even if we can't see what the hidden planets are, we’re still discovering a lot about planetary systems.”
“There are still many unknowns about the process of planet formation, but we think these new observations from Vega will help constrain models of planet formation.”
The two papers are astrophysical journal.
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Kate Y.L. Sue others. 2024. Imaging the Vega debris system using JWST/MIRI. APJin press. arXiv: 2410.23636
Skylar G. Wolf others. 2024. Hubble Space Telescope probes deep into the scattered light dust ring around Vega. APJin press. arXiv: 2410.24042
Source: www.sci.news
