For the first time discovered a planetary system with two exoplanets similar to Mercury 127 light years | sorae Portal site to space

From the Portuguese Institute of Astrophysics and Space Sciences (IA)Susanna BarrosResearch team led byConfirmed a planetary system with a total of 5 exoplanetsAnnounce your search results. 2 out of 5 planetsSimilarities with Mercurywas noted,Why do dense rocky planets form?It is hoped that this will lead to clarification

■ 5 exoplanets confirmed, 3 of which are lighter than Earth

What was reported this time is a fixed star about 127 light-years away in a “grid” direction in the southern sky「HD 23472」5 extrasolar planets revolve around the orbit「HD 23472 d」 「HD 23472 e」 「HD 23472 f」 「HD 23472 b」 「HD 23472 c」(in order of distance from star *). In this article, it is written as “Planet D” below.

Two outer planets b and c were reported in 2019, and three inner planets d, planet e and planet f were reported by the research team.“Super Earth”I’ve been with. The orbital period, radius and mass for each planet are declared as follows.

● HD 23472 d
・ Revolution period: 3.98 days
・ Radius: about 0.75 times that of the Earth
・ Mass: about 0.55 times the mass of the Earth

● HD 23472 AH
・ Revolution period… 7.90 days
・ Radius: about 0.82 times that of the Earth
・Mass: about 0.72 times that of Earth’s

● HD 23472 f
・ Revolution period: 12.16 days
・ Radius: about 1.14 times that of the Earth
・ Mass: about 0.77 times that of Earth’s

● HD 23472 b
・ Revolution period: 17.67 days
・ Radius: about 2.00 times the Earth
・ Mass: about 8.32 times that of Earth’s

● HD 23472 c
・ Revolution period: 29.80 days
・ Radius: about 1.87 times that of the Earth
・ Mass: about 3.41 times the mass of the Earth

The parent star, HD 23472, is slightly smaller than the Sun.star k(The radius is about 0.71 times the mass of the Sun, the mass is about 0.67 times the mass of the Sun, and the surface temperature is about 4400°C.) Equilibrium temperatures for the surfaces of the five planets areAbout 200 to 630 degrees CelsiusBoth are considered extreme high temperatures for terrestrial life.

* The name of an exoplanet is the name of the star with lowercase letters added in the order that begins with the letter “B”. The alphabet is given according to the order in which the planets were discovered and the distance from the fixed star, but even if a new planet is discovered later in the same planetary system, the already specified name will not be changed. Alphabetical order is not necessarily the order of distance from the star, and in some cases planet d is closer to the star than planet c, as in this case.

■ Maybe we can get a clue to get close to the mystery of Mercury’s formation?

[▲ عطارد مأخوذ بواسطة مسبار ميركوري التابع لناسا “ماسنجر” (Credit: NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie)]

This time, focus on the insidePlanet D and Planet ETwo. When the research team estimated the average density and internal composition of each planet, Planet D and Planet EHigh iron content and medium high density(Planet D equals 7.5_-3.1^+3.9 g/cm³Planet e 7.5_-3.0^+3.9 g/cm³）The probability that the nucleus (nucleus) is responsible for about 45% of the masshas been shown.

There are four rocky planets in the solar system, but the deepest areMercury has a large core made of iron and nickelIt is known that, according to the research team, the newly discovered exoplanets such as planet d and planet e are similar to Mercury.“Super Mercury”Also known as「K2-229 B」It is said that only six have been known, including this being the first time that two centuries of Mercury have been found in the same planetary system.

According to the research team, it is not yet known why Mercury has such a large core.Part of the mantle that covers the heartButLost in a giant collisionorevaporated due to high temperatureIt is said that it is possible.Two newly discovered supernatural mercuryClues to Solve the Mystery of Mercury’s FormationIt may be given to you by the Canary Institute for Astrophysics (IAC), which was involved in the researchAlexander Suarez さ ん“The chances of a Mercury supercomponent collision are already greatly reduced, as it seems very unlikely that two giant impacts will occur in the same planetary system,” he commented.

Also, the IACs that participated in the studyJohnny GonzalezIt indicates that knowing more about the formation of a newly discovered exoplanet is essential to understanding how it formed. European Southern Observatory (ESO) is under constructionEuropean Very Large Telescope (ELT)We look forward to future observations using, to study the composition of planetary surfaces and atmospheres.

Connection:Live image of an exoplanet 355 light-years away from the James Webb Space Telescope

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• Image Credit: NASA/JPL-Caltech; NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie
• I to Two ultra-rare Mercury have been discovered around the same star
• IAC – Astronomers discover a planetary system with three super-Earths and two Mercury

Text / Matsumura Takehiro