The second planet recently detected around the star next to the Sun appears to be surrounded by a ring system, like Saturn.
Artist’s rendering of the planets orbiting Proxima Centauri, the closest star to the Sun, just 4.22 light-years away.
In 2016, astronomers working at the European Southern Observatory (ESO) confirmed the existence of a terrestrial planet around the nearest stellar neighbor: Proxima Centauri. The discovery of this exoplanet (Proxima b) It was momentous for many reasons, including the fact that it was similar to Earth in size and its orbit was within the habitable zone.
Earlier this year, using the radial velocity method, the Instituto Nazionale di Astrofisica (INAF) of Italy found a second exoplanet (Proxima c) orbiting the same star.
Now, based on the separation between the two planets, another team led by INAF attempted to observe this new planet using the Direct Image Method. And while they were not entirely successful, his observations raise the possibility that this planet has a ring system around it.
SPHERE.
For the sake of your study, which recently appeared in the magazine Astronomy & Astrophysics, the team based on the data obtained by the instrument Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) in the Very Large Telescope (VLT) of ESO. This extreme adaptive optics and coronagraphic system is dedicated to the characterization of exoplanet systems at optical and near infrared wavelengths.
For years, SPHERE has been revealing the existence of protoplanetary disks around distant stars, something that is extremely difficult to do with conventional optics. However, this particular set of data was collected during the SHERE Infrared Survey for Exoplanets (SHINE), where the instrument was used to image 600 nearby stars in the near-infrared spectrum.
Relying on SPHERE’s high contrast and high angular resolution, the purpose of this survey was to characterize new planetary systems and explore how they were formed. One such system was Proxima Centauri, a low-mass M-type (red dwarf) star located just 4.25 light years from our Solar System. At the time of the survey, the existence of Proxima c was not yet known.
Like Proxima b, Proxima c was discovered using the Radial Velocity method (also known as Doppler Spectroscopy). This consists of measuring the movement of a star from one side to the other (or “wobble”) to determine if the gravitational influence of a system of planets acts on it. However, the team was confident that if Proxima c produced a large enough infrared signal, SPHERE would have detected it.
Unfortunately, the SPHERE data did not reveal any clear detection of Proxima c. What they found was a candidate signal that had loud noise and an orientation of its orbital plane that fit well with a previous image taken with the Atacama Large Millimeter / submillimeter Array (SOUL). They also noted that their orbital position and movement were not consistent with what was observed by ESA’s Gaia mission.
Finally, they discovered that the candidate had an unexpectedly high apparent brightness (flux) for a planet orbiting a red dwarf star. Because of this, the team was unable to say for sure if what they observed was really Proxima c.
Artist rendering of a solar sail approaching the potentially habitable planet Proxima b. Credit: PHL @ UPR Arecibo.
However, this last element raised another possibility that the team had to consider, that the unusual shine may be the result of a circumplanetary material. In other words, they theorize that the brightness could be caused by a ring system around Proxima c, which would be radiating additional light in the infrared spectrum and contributing to the overall brightness.
“In this case, we imagine a conspicuous ring system or the production of dust by collisions within a swarm of satellites, or the evaporation of dust that increases the luminosity of the planet. This would be unusual for extrasolar planets, with Fomalhaut b, for which there is no dynamic mass determination, as the only other possible example, “explains the study’s first author, Raffael Gratton of the Padua Astronomical Observatory.
This makes Proxima c a prime target for follow-up studies using radial velocity measurements, near-infrared imaging, and other methods. In addition, next-generation telescopes, such as the Thirty Meter Telescope (TMT), Giant Magellan Telescope (GMT), and ESO’s Extremely Large Telescope (ELT), will be suitable for direct imaging studies of this system to characterize better to Proxima c.
Source: Universe Today
