Newly discovered exoplanets turned out to be hot Jupiters. However, they are at least 10% larger than Jupiter
Hot Jupiters are similar in characteristics to the mosta large planet in the solar system with an orbital period of less than 10 days. These exoplanets have very high surface temperatures. The reason is the very close rotation around their parent stars.
A group of astronomers led by Rosanna H.Tilbrook of the University of Leicester, UK, announces the opening of four new facilities of this type. The scientists used the NGTS group of 12 independently installed 20-centimeter Newtonian telescopes at the Paranal Observatory in Chile.
Researchers have identified transit signalsin the light curves of four stars during the observation campaign throughout the year. The planetary nature of these signals was later confirmed by follow-up observations from the South African Astronomical Observatory (SAAO) and by analyzing data from the NASA Transiting Exoplanet Survey Satellite (TESS).
Recently discovered exoplanets receiveddesignations NGTS-15b, 16b, 17b and 18b. All four objects are short-period planets (with an orbital period of less than five days) orbiting different G-type main sequence stars.
NGTS-15bwith a radius of about 1.1 Jupiter's radius isthe smallest planet of the newly discovered quartet. It is about 25% less massive than Jupiter and orbits its host every 3.27 days at a distance of 0.044 AU. e. from him. The planet's equilibrium temperature is 1146 Kelvin (872 °C). The host star, NGTS-15, belongs to the spectral class G6V, has a mass similar to the mass of the Sun, but about 5% less. Observations indicate that NGTS-15 is about 3.28 billion years old, has an effective temperature of about 5,600 K (5,327 °C), and is located about 2,600 light years away.
Although NGTS-16bis the largest exoplanet knownthe article reports its mass is only 0.67 that of Jupiter. Its orbital period is 4.84 days, its distance from the star is 0.05 AU. e., and its equilibrium temperature is at the level of 1,177 K (904 °C). NGTS-16 is a solar mass star of spectral class G7V with a radius of about 1.21 solar radii. The star's age is estimated at 10.29 billion years, and its effective temperature is 5,550 K (5,277 °C). The planetary system is located approximately 2,900 light years from Earth.
NGTS-17b- the most massive exoplanet of the four recentlyopen, since its mass was calculated to be approximately 0.764 that of Jupiter. The planet is about 24% larger than Jupiter, and its equilibrium temperature is 1,457 K. The results show that NGTS-17b orbits its 9.2 billion-year-old host every 3.24 days at a distance of about 0.04 AU. e. from the parent star NGTS-17. It is about 3,400 light-years from Earth, slightly more massive than the Sun, and has a radius of almost 1.34 Suns. Effective temperature: 5,650 K (5,377 °C).
Extrasolar planet NGTS-18b- the least massive of those described in the article.Its mass is only 0.41 that of Jupiter; however, it is about 21% larger than Jupiter. The exoworld is separated from NGTS-18 by 0.045 AU. e., and it takes only 3.05 days to completely circle around its owner. The equilibrium temperature of this planet is estimated to be approximately 1,381 K (1,108 °C). As for the parent star of spectral class G5V, its radius is about 1.4 solar radii, and its mass is similar to the mass of our Sun. The star is 10.8 billion years old, has an effective temperature of about 5,610 K (5,337 °C), and is 3,600 light-years from Earth.
Taking into account all the results, the authorsThe papers concluded that three of the four newly discovered objects, namely NGTS-16b, NGTS-17b and NGTS-18b, are likely “inflated” exoplanets. Such planets have extremely low density—less than 0.1 grams per cubic centimeter. The texture of these planets has been compared to cotton candy.
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NGTS - Next Generation Transit Survey