by Astronomers have discovered not one but two planetary systems with sun-like stars at their cores.
Both of these systems contain the minor planets of Neptune and one of them contains a large “Super-Jupiter” world, all of which are much larger than Earth. Studying the realms could lead to a better understanding of how planets form and evolve around sun-like stars – also known as “solar analogues”.
Both systems were discovered using NASA’s Transiting Exoplanet Survey Satellite (TESS) and the 1.93 meter telescope at the Observatoire de Haute-Provence (OHP) in southern France. The OHP telescope has a pedigree when it comes to detecting extrasolar planets, or “exoplanets”. It is the tool of astronomers Michel Mayor and Didier Queloz used to discover 51 Pegasi in 1995, discovered the first exoplanet orbiting a sun-like star.
These two newly discovered systems contain at least three exoplanets, named TOI-1736 b, TOI-1736 c, and TOI-2141 b, all of which connect together. exoplanet a catalog that has grown to over 5,500 entries since the mid-1990s.
“We report the detection and characterization of two planetary systems around the solar analogs TOI-1736 and TOI-2141 using TESS photometry data and spectroscopic data obtained with the SOPHIE instrument on the 1.93 m telescope at the OHP,” Institute of Astrophysics of Paris scientist and lead author of the research Guillaume Hébrard wrote with his co-authors in a paper published in the journal Astronomy & Astrophysics. “We performed a detailed spectroscopic analysis of these systems to obtain the precise radial velocities and physical properties of their host stars.”
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TOI-2141: A planetary system around an old star
TOI-2141 is the first planetary system discovered by Hébrard and his colleagues, located about 250 light years from World and focused on a star of comparable size the sun but it seems to be older than our star. We know this because the star TOI-2141 shows a lack of chemical elements heavier than hydrogen and helium, called “metals.” In contrast, our 4.6-billion-year-old sun is highly enriched in such metals. With some calculations, the team realized that the metal ratio indicates that the newly studied star is about 7.5 billion years old.
The planet in this system, TOI-2141 b, was seen crossing, or ‘transiting,’ the face of its parent star, blocking some of the light coming from the star and thus reducing the star from the old point of the telescope. The team was able to determine that this planet is about three times as wide as Earth, with a mass about 24 times that of our planet, making it a minor planet.Neptune exoplanet.
TOI-2141 b is located about 12 million miles from its star, which is about 13% of the distance between Earth and the sun. This means that mini-Neptune completes an orbit once every 18.3 days on Earth, and this proximity raises its temperature to around 840 degrees Fahrenheit (450 degrees Celsius).
The density of this planet and its warm surface temperature indicate that it consists of a rocky core surrounded by an atmosphere full of water vapor. To date, TOI-2141 b is the only planet found in the TOI-2141 system, but the team has not yet ruled out the possibility of other small planets orbiting the sun-like star.
And, as impressive as this first system, the second planetary system the team discovered is a little more unique.
The exotic TOI-1736
Located around 290 light year from Earth, TOI-1736 is slightly more exotic than TOI-2141. At first glance, its primary star is insignificant, being about the same age as the sun, about 4.9 billion years old, about the same size as the sun, just 15% larger than our star, and even about the same temperature.
However, the TOI-1736 system is extraordinary because its main star is a secondly, smaller companion star, making this a binary system.
Enormous stars commonly found in binary systems, but this double lifestyle is rarer for stars the size of the sun, and only about 44% of solar analogues are found with a companion. Even stranger is that TOI-1736’s companion star is so far from the main star that the exoplanets found by the team only orbit the system’s main star.
Specifically, Hébrard and his colleagues found two planets in this exotic star system. The next one is a mini-Neptune with a width of about 2.5 times that of Earth and a mass of 13 times that of our planet. This planet, TOI-1736 b, orbits its star only 6.5 million miles, which is about 7% of the distance between Earth and the sun, and completes an orbit in about 7.1 Earth days. Because of TOI-1736 b’s proximity to its star, it has a temperature of around 1,500 degrees Fahrenheit (800 degrees Celsius).
The second planet of the system, TOI-1736 c, is a so-called “super-Jupiter” with a mass of about 2,800 times that of Earth and a width of about 9 times that of Earth. Jupitermaking it a cloud 99 times wider than Earth.
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TOI-1736 c is located about 128 million miles from its star, which is about 1.3 times the distance between Earth and the sun, meaning it completes an orbit about once every 570 Earth days. This distance also puts the planet in the habitable zone of its parent star — the distance from which water can exist in a liquid state. TOI-1736 c is a gas giantso there is no solid surface, but there could be moons with atmospheres that allow liquid water to exist on their surface — perhaps making them habitable?
The answers to such questions will come time; In the meantime, the team is focused on some signs of a third planet that seems to liev around TOI-1736. Soon, they plan to investigate this clue with the SOPHIE spectrograph at the OHP.
