discovered an exoplanet about 130 light-years away via direct imaging observation results of the Subaru telescope | Sorae Portal to space

A research team headed by Thane Currie of the National Astronomical Observatory in Hawaii used the Subaru Telescope from the same observatory.Live imaging of an exoplanet 130 light-years awayAnnounce search results.

The exoplanet is called HIP 99770 b, and it lies about 17 AU from the star HIP 99770 in the constellation Cygnus.（※1）It orbits in a distant orbit and has an estimated mass of about 15 times that of Jupiter. The main star, HIP 99770, is an A-type star with a mass of about 1.8 times that of the Sun, a surface temperature of 8,000 K (about 7,727 °C), and an apparent brightness of 4 that can be seen with the naked eye from Earth.

* 1 … 1 astronomical unit (au) = about 150 million km, derived from the average distance from the Sun to the Earth. 17 AU is about three times the distance from the Sun to Jupiter (about 5.2 AU).

Because planets are dark celestial bodies found near bright stars, it is difficult to directly observe exoplanets orbiting distant stars. According to the National Aeronautics and Space Administration (NASA) Exoplanet Database, the number of known exoplanets reached 5,332 as of April 10, 2023. They were detected indirectly using exoplanet detection. According to the National Astronomical Observatory of Japan, there have so far been only about 20 direct images of celestial bodies that are too small to be called planets, yet so close to their stars.

In addition, in order to detect exoplanets by direct imaging, it is necessary to observe every star that is likely to have a planet in its orbit. In recent years, high-resolution observatories have appeared that can capture stars and planets separately using adaptive optics (AO) technology, which cancels out the effects of fluctuations in the Earth’s atmosphere. However, if we can’t narrow down the candidate stars that are likely to have planets in orbit, then we have to continue observing a large number of candidates from the edge.

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Observational data obtained by the European Space Agency’s (ESA) Gaia space telescope and its predecessor, the Hipparcos observation satellite, are drawing attention. The Gaia Space Telescope and the Hipparcos satellite specialize in astronomical measurement and study of the positions and motions of celestial bodies. The latest observation data of the Gaia Space Telescope “DR3 (Data Release 3)” released in June 2022 contains the positions and brightnesses of about 1.8 billion stars, as well as the annual cycles of about 1.5 billion stars. It contains information such as parallax and true motion (the distance to the stars and the apparent motion of the stars on the celestial sphere).

Related: Over 1.8 billion items noted. The latest data from the European space telescope Gaia have been released (June 14, 2022).

The research team captured stars with position fluctuations that indirectly indicate the presence of planets from astronomy data, and detected them using the Subaru Telescope’s SCExAO and CHARIS instruments.（※2）As a result, it was reported that HIP 99770 b was discovered this time. In normal direct imaging, mass is estimated based on brightness, which leads to significant errors.

*2 SCExAO, which can enhance the image obtained with adaptive optics to cancel the effects of atmospheric fluctuations, blocking only the light from the parent star while keeping the light from the planet. Coronagraph’s superior adaptive optics. Charisse: A near-infrared imaging spectrometer that can obtain detailed information about the planets (atmospheric temperature, pressure, chemical composition, etc.).

[▲كوكبخارجالمجموعةالشمسية”HIP99770b”تمتصويرهبواسطةتلسكوبسوبارومنيوليو2020إلىأكتوبر2021(Credit:T.Currie/SubaruTelescope،UTSA)]

According to the National Astronomical Observatory of Japan, HIP 99770 b is the first exoplanet discovered with direct imaging associated with astrometry. Professor Motohide Tamura of the Center for Astrobiology at the University of Tokyo, who was involved in the research, said, “With this research method, we will continue to discover new exoplanets. It will not be a dream for future observations using next-generation telescopes and adaptive optics to observe ‘second Earth’ in this way.”

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The mass of HIP 99770 b, about 15 times the mass of Jupiter, is close to the boundary between a brown dwarf (a celestial body between a star and a planet) and a planet. The National Astronomical Observatory of Japan and Center for Astrobiology also stated in a press release that “usually the mass of a planet is less than about 13 that of Jupiter,” and added, “This star (*HIP 99770) is much heavier than the Sun,” no wonder A planet with a mass of 15 planets is born from a stellar disk.

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