- 3357 - EXOPLANETS - how to explain hot Jupiters? We have four terrestrial planets. Earth being number 3. Then there are four gaseous planets. Jupiter being the biggest. The planets we discover in the faraway solar systems we call exoplanets. We tend to discover the biggest one like Jupiter.
--------------------- 3357 - EXOPLANETS - how to explain hot Jupiters?
- While our robotic explorers have toured our solar system, the only place beyond Earth where humans have stood is the Moon. That's also the next place we'll send our astronauts.
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- NASA's budgeted plans are firmly focused on reviving human moon exploration, with hopes to land astronauts on the Moon again in the 2020s. As for Mars, the earliest NASA might send people there is 2035 .
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- The hunt for planets beyond our solar system has turned up more than 4,000 far-flung worlds, orbiting stars thousands of light years from Earth. These extra-solar planets are a menagerie, ranging from rocky super-Earths and miniature Neptunes to colossal gas giants. We call them “exoplanets”.
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- Among the more confounding exoplanets discovered to date are "hot Jupiters". These are massive balls of gas that are about the size of our own Jovian planet but that orbit around their stars in less than 10 days, in contrast to Jupiter's 12-year orbit.
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- Scientists have discovered about 400 “hot Jupiters” to date. But exactly how these weighty planets came to orbit their stars so close remains one of the biggest unsolved mysteries in planetary science.
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- One of the most extreme ultra-hot Jupiters is a gas giant that is about five times Jupiter's mass and orbits around its star in just 16 hours. The planet's orbit is the shortest of any known gas giant to date. That’s fast!
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- Due to its extremely tight orbit and proximity to its star, the planet's day side is estimated to be at around 3,500 Kelvin. A planet about as hot as a small star. This makes the planet, designated “TOI-2109b“, the second hottest detected so far.
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- Judging from its properties, astronomers believe that “TOI-2109b” is in the process of "orbital decay," or spiraling into its star, like bathwater circling the drain. Its extremely short orbit is predicted to cause the planet to spiral toward its star faster than other hot Jupiters.
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- The discovery, which was made initially by NASA's “Transiting Exoplanet Survey Satellite” (TESS) presents a unique opportunity for astronomers to study how planets behave as they are drawn in and swallowed by their star.
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- In our lifetime we will not see the planet fall into its star. But give it another 10 million years, and this planet might not be there.
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- TOI-2109 is a star located in the southern portion of the Hercules constellation, about 855 light years from Earth. Over nearly a month, the spacecraft collected measurements of the star's light, which the TESS science team then analyzed for transits periodic dips in starlight that might indicate a planet passing in front of and briefly blocking a small fraction of the star's light.
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- The data from TESS confirmed that the star indeed hosts an object that transits about every 16 hours. By analyzing measurements over various optical and infrared wavelengths, the team determined that TOI-2109b is about five times as massive as Jupiter, about 35 percent larger, and extremely close to its star, at a distance of about 1.5 million miles out.
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- Mercury, by comparison, is around 36 million miles from the Sun.
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- The TOI-2109 planet's star is roughly 50 percent larger in size and mass compared to our Sun. From the observed properties of the system, the researchers estimated that TOI-2109b is spiraling into its star at a rate of 10 to 750 milliseconds per year, faster than any hot Jupiter yet observed.
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- Given the planet's dimensions and proximity to its star, the researchers determined TOI-2109b to be an ultrahot Jupiter, with the shortest orbit of any known gas giant. Like most hot Jupiters, the planet appears to be tidally locked, with a perpetual day and night side, similar to the Moon with respect to the Earth.
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- From the month-long TESS observations, the team was able to witness the planet's varying brightness as it revolves about its axis. By observing the planet pass behind its star (known as a secondary eclipse) at both optical and infrared wavelengths, the researchers estimated that the day side reaches temperatures of more than 3,500 Kelvin.
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- The planet's night side brightness is below the sensitivity of the TESS data, which raises questions about what is really happening there. Is the temperature there very cold, or does the planet somehow take heat on the day side and transfer it to the night side?
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- The researchers hope to observe TOI-2109b with more powerful tools in the near future, including the Hubble Space Telescope and the soon-to-launch James Webb Space Telescope. More detailed observations could illuminate the conditions hot Jupiters undergo as they fall into their star.
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- Ultrahot Jupiters such as TOI-2109b constitute the most extreme subclass of exoplanet. But, they are the easiest to find. Bright and short orbits are the reason. We have only just started to understand some of the unique physical and chemical processes that occur in their atmospheres processes that have no analogs in our own solar system.
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- Future observations of TOI-2109b may also reveal clues to how such orbiting systems come to be in the first place. How does a planet as massive and large as Jupiter reach an orbit that is only a few days long? I am still working on that one.
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November 25, 2021 EXOPLANETS - how to explain hot Jupiters? 3356
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