Scientists from the University of New Mexico (UNM) and the Massachusetts Institute of Technology (MIT) discovered and confirmed the two longest exoplanets ever found by TESS. These long-period large exoplanets orbit the K dwarf star and belong to a class of planets known as hot Jupiters, with an orbital period of 10-200 days and at least six times the radius of Earth. This latest discovery opens up exciting research opportunities for the future search for long-period planets like those in our solar system.

The study titled “TOI-4600 b and c: Two long-period giant planets orbiting an early K-dwarf” will be published in the forthcoming issue. Astrophysical Journal Letters. The exoplanets TOI-4600 b and c were discovered using photometric data from the Transiting Exoplanet Survey Satellite (TESS) and have been accompanied by observations with ground-based telescopes as they provide better resolution.

The observing strategy adopted by NASA’s TESS, which divides each hemisphere into 13 sectors studied over approximately 28 days, provides the most comprehensive search for transiting planets in the sky. This approach has already proven its ability to detect both major and minor planets around different types of stars. In the example of TOI-4600, this star is a K dwarf, also known as an orange dwarf; this means stars that are slightly smaller and cooler than the Sun.

At least two passes of their host stars within TESS’s observation range so that exoplanets can be detected in the correct period by the Science Operations Processing Center (SPOC) pipeline and the Rapid Imaging Pipeline (QLP) scanning the 2-minute and 30-minute TESS must. data rates, respectively. Since 74% of the total TESS sky coverage is observed for only 28 days, most of the exoplanets detected by TESS have periods shorter than 40 days. Therefore, TOI-4600 b’s 82.69 days, or approximately 3 months, and TOI-4600 c’s, 482,82 days, or 16 months, make exploration even more valuable.

Collaborators including Ismael Mireles of the University of New Mexico and Diana Dragomir, an assistant professor of physics and astronomy at the University of New Mexico, and collaborators from the Massachusetts Institute of Technology and the University of Bern, analyzed the paper’s lead author. data in order. Measure the periods and magnitudes of these planets.

After the initial detection of the transits, Mireles and his team needed to confirm that they were real planets and determine which signal the star was coming from. TESS’s diagnostic tools showed that the signals from the target area were indeed real.

They observed the transit with the help of Subgroup 1 (SG1) of the TESS Tracking Observation Program (TFOP), a global network of professional and amateur astronomers with access to small and large telescopes, thus confirming the existence of this planet to researchers. indeed, another factor that Mireles and his team had to consider in the target was the masses and sizes of the planets. To achieve this, they modified the velocity measurement by observing how much the host star wobbled as it pulled the planet.

“We saw very little movement of the target star when we took the measurements. So you may be responsible for what we saw when you started. These two things combined greatly rule that out. We were pretty sure we had two planets back then,” Mireles said.

The researchers found that these two planets and the inner planet TOI-4600 b have a period of 82.69 days and are almost seven times Earth’s in radius. It is between the dimensions of Neptune and Saturn. The estimated temperature of this planet, named TOI-4600 b, is about 170 degrees Fahrenheit; it’s hot but colder than most planets astronomers have found.

The second planet found, TOI-4600 c, is about nine and a half times the radius of Earth, or about the size of Saturn. It first passed by only once when TESS first observed the star, then a second time almost three years later.

“If you have two passes, you have an idea of ​​what periods can be like. It could be 965 days separating them, half, third, quarter, etc. Mireles said shorter periods can be ignored, as TESS has observed the star for a long time and only two periods remain: 965 days or half that.

The researchers used a model developed by co-author Hugh Osborne of the University of Bern to compare possible orbital periods and determine which is more likely, and found that 965 was half the time, or 482.82 days. TOI-4600 c’s period of 482.82 days makes it the longest planet found by TESS to date, and one of the coldest planets found by TESS, with a temperature of around -110 degrees Fahrenheit.

Kathryn Hesse, head of TOI and validation at MIT, collaborated with Mireles and the team on the analysis of the TESS data. Hesse helped process and analyze large volumes of data and put the system in the context of other multi-planetary systems found by missions, including TESS. Comparing the TOI-4600 system with other discovered exoplanet systems helped investigate features such as formation times and processes, and helped the researchers begin to place the system in the wider context of exoplanet systems.

“The main thing is to try to learn more about planet formation, because based on what we know about exoplanets we’ve found, there’s nothing like the Solar System right now. The interesting thing is we want to learn about the formation of these planets. We have over 5,000 exoplanets right now, but none of these systems are actually like the Solar System, Mireles said, “So we want to learn how these different types of systems formed and moved.”

Mireles and researchers are interested in these findings because of the discovery of two long-period giant planets; This is a configuration that astronomers don’t see often, even though there are four long-period giant planets or one long-period planet in the solar system found. .

As Mirels points out, this raises further research discussion and questions: “Do we want to learn how they formed? Are there other planets in this system? This tells us how these giant planets affect smaller planets that may or may not be there, and why they’re not there. “There are things we still want to learn and that will tell us a lot about the formation of the planet.”

Finally, Mireles encourages community scientists and astronomy enthusiasts to join and become involved in this scientific exploration. There will be another possible transit on Monday, October 16 for those interested and willing to watch to confirm that the outer planet’s period is indeed 482 days. People with smaller telescopes can also participate if they have the right tools.

“Of course there are social scientists or amateur astronomers who have their own telescopes and help us with all these observations. There is actually a group of people who have access to telescopes that confirm that a transit event has occurred on the star we are interested in. ‘ said Mireles.

“People who are retired or have other jobs but are also amateur astronomers provide very useful data to help confirm these planets. The results they produce are of professional quality. Dragomir, associate professor of the Department of Physics and Astronomy at the National University of Ukraine, said: “It’s critical to the planetary verification process,” said the source.