New multiplanetary system discovered in our galactic neighborhood


Using NASA’s Exoplanet Survey Satellite (TESS), astronomers at MIT have discovered a new multiplanetary system in our galactic neighborhood.

The system, which hosts at least two Earth-sized terrestrial planets, lies about 33 light-years from Earth. It is one of the closest known multiplanetary systems to ours.

The heart of the system is a small, cool M dwarf star called HD 260655. The planets of the system are probably not habitable due to their relatively narrow orbits which make temperatures too high to keep liquid water on the surface.

Scientists are excited about this system because its star’s proximity and brightness will allow them to better understand the properties of planets and the signals of any atmosphere they may contain.

“The two planets in this system are considered the best targets for atmospheric study because of the your star shines. Is there an atmosphere rich in volatile matter around these planets? And are there any signs of water-based or carbon-based species? These planets are fantastic testbeds for these explorations,” said Michelle Kunimoto of MIT’s Kavli Institute for Astrophysics and Space Research.

The system was discovered in October 2021 when Kunimoto monitored incoming satellite data from the star HD 260655.

After several detections, the signals were quickly classified as two objects of interest TESS – or TOI. As a rule, the process of categorizing and subsequently confirming new planets it may take several years. For HD 260655, this process has been greatly shortened using file data.

After identifying two potential Earth-sized planets around HD 260655, astronomers set out to see if other telescopes had already identified the system. The High-Resolution Ladder Spectrometer (HIRES) listed the system in its Star Survey, and it was also recorded by CARMENES.

To make sure that the signals received from TESS were indeed coming from two planets in orbit, the scientists examined the data from HIRES and CARMENES.

the two withdrawals measure gravitational oscillation of a star, also known as its radial velocity, as reported by Technology Explorer.

“Every planet orbiting a star has a small gravitational tug on its star. We’re looking for any slight movement of that star that might indicate a planetary-mass object is tugging,” Kunimoto said.

The scientists found statistically significant signs indicating that those detected by TESS were indeed two orbiting planets.

Then they looked at the data more closely to determine the properties of the two planets – their orbital period and their size.

They found that the inner planet, called HD 260655b, orbits the star every 2.8 days and is approximately 1.2 times larger than Earth. The second outer planet, HD 260655c, orbits every 5.7 days and is 1.5 times larger than Earth.

The scientists also calculated the mass of the planets, directly related to the amplitude by which each planet orbits around its star.

They found that the inner planet is about twice the mass of Earth, while the outer planet is about three times the mass of Earth.

From its size and mass, the team calculated the density of each planet. The smaller inner planet is slightly denser than earth, while the larger outer planet is somewhat less dense. Based on their density, both planets are likely terrestrial or rocky.

The surface of the inner planet is 710 kelvins, while that of the outer planet is around 560 kelvins, based on their short orbits.

“We consider the beach outside the habitable zone to be too warm for liquid water to exist on the surface,” Kunimoto noted.

“But there could be more planets in the system. Many multiplanetary systems host five or six planets, especially around small stars like this. We hope to find others and we could be habitable. It is an optimistic thought.

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