[▲ Imagination of the exoplanet “Kepler 1708b” (right) and the exoplanet candidate “Kepler 1708b-i” (left) (Credit: Helena Valenzuela Widerström)]
Columbia UniversityDavid KippingThis is the second research group in the history of observation.Candidate for “exoplanet”Announced the research results that were found.An exoplanet revolves around a star other than the sun.A satellite that revolves around an “exoplanet”That. Kipping et al. Reported the discovery of the first exoplanet candidate in the history of observation in October 2018, and confirmation is awaited including this exoplanet candidate.
■ It is possible that a “satellite” 2.6 times larger than the Earth is revolving on a planet the size of Jupiter.
What was reported this time is an exoplanet about 5500 light-years away in the direction of Cygnus.“Kepler 1708b”It is a candidate for a satellite that is said to revolve.From the research group“Kepler 1708b-i”Is called.The exoplanet Kepler 1708b is a sun-like star with a diameter of about 0.89 times that of Jupiter and a mass of less than 4.6 times that of Jupiter.“Kepler 1708”It is thought to revolve in an orbit about 1.6 astronomical units
away from (about 1.11 times the diameter and about 1.09 times the mass compared to the Sun) in a cycle of about 737 days.
*… One astronomical unit (au) is approximately 150 million km, derived from the average distance from the earth to the sun.According to the research group, the exoplanet candidate Kepler 1708b-iAbout 2.61 times the diameter of the earthandMass is less than 37 times that of the earth, Kepler 1708bRevolves every 4.6 daysIt is estimated that it is.Exoplanet to the last“candidate”
However, it seems that there is a possibility of a relatively large satellite with a diameter ratio of about 0.26 times and a mass ratio of less than 0.11 times that of Jupiter-sized planet Kepler 1708b.In the solar system“satellite”The existence of the celestial body is very common.Earth moonOf courseDozens of satellites on Jupiter and SaturnHas been found andSome asteroids have satellites
there is. Some of the exoplanets that have already been confirmed to have more than 4,800 may have satellites, but no exoplanets have been confirmed to exist to date.To discover satellites outside the solar system that are smaller than planets, Kipping and his colleagues are like Jupiter and Saturn, which have many satellites.A low-temperature giant gas planet that has a relatively long orbital period and orbits away from the main star, the star.
https://www.youtube.com/watch?v=FLq8CJ5HQwE
[▲ Video showing how the brightness of a star changes due to the transit of an exoplanet (Credit: ESO / L. Calçada)]Kepler Space Telescope“Transit method”We made observations using.The transit method is when a planet crosses in front of a star.“Transit”When the phenomenon ofThe brightness of the star becomes very slightly darkBy capturing the situation,Indirectly detects the existence of exoplanetsIt is a method to do. Analysis shows that only one of the 70 exoplanets,A signal suggesting the existence of a satellite only in Kepler 1708b
Was confirmed. According to the research group, the probability of false positives is 1 percent.As I mentioned at the beginning, Kipping and his colleagues used to use the Kepler Space Telescope to search for exoplanets.“Hubble” Space TelescopeWe are analyzing the observation data of the exoplanet in October 2018, about 7500 light-years away.“Kepler 1625b”Seems to be revolvingExoplanet candidate “Kepler 1625b-i”Is reporting.Kepler 1625b has about the same diameter as Jupiter, but its satellite candidate Kepler 1625b-iAbout the size of Neptune
It is said that there is.
[▲ The figure showing the state of transit by Kepler 1625b detected by the Hubble Space Telescope and its exoplanet candidates (in order of 1 to 4). The light curve of the main star (the curve showing the luminosity of celestial bodies that changes over time) shows dimming due to the passage of exoplanet candidates (4) (Credit: NASA). , ESA, D. Kipping (Columbia University), and A. Feild (STScI))]The exoplanet candidate Kepler 1708b-i reported this time is also considered to be a large satellite that is more than twice the size of the Earth, but the two exoplanet candidates are huge due to observational restrictions.It was easy to detect the signal because it was huge
It can be said. “Most of the time, the first thing you’ll find in any survey is weird. Large satellites are easy to detect, even with limited sensitivity,” says Kipping.Whether Kepler 1708b-i or Kepler 1625b-i really exist isConfirmation by future observationI have to wait.University of Washington ProfessorEric Agol
As we say, there is still the possibility of data fluctuations due to the noise of stars or observation equipment.
Kipping says that the discovery of extrasolar planets, which are more heterogeneous than the planets of the solar system, “revolutionized our understanding of the formation of planetary systems.” If the existence of exoplanets is confirmed and research on their properties and origins progresses, the understanding of the formation of planets and satellites will be further advanced.
Related: Is there liquid water on the surface of the satellites of rogue planets wandering in space?
Image Credit: Helena Valenzuela Widerström
Source: Columbia University
Sentence / Takehiro Matsumura
