Astronomers find evidence of the existence of the first known exomoon outside our solar system

Astronomers may have discovered the first known exomoon.

Astronomers using the Hubble and Kepler space telescopes have discovered fascinating evidence of the existence of the first known moon outside our solar system. It is in orbit on a gaseous giant planet at 8000 light-years.

According to findings published in the journal Science Advances, the exomoon candidate – moons revolving around planets in other star systems – is unusual because of its large size, comparable to Neptune's diameter.

According to researchers at Columbia University in the United States, such huge moons do not exist in our own solar system, where nearly 200 natural satellites have been cataloged.

"If confirmed by Hubble's subsequent observations, the discoveries could provide essential clues about the development of planetary systems and could lead experts to revisit theories of moon formation around planets," said Kipping.

EXPRESS, ORBITS AND PERIODS

The researchers analyzed data from 284 planets discovered by Kepler that were in relatively wide orbits, with periods greater than 30 days, around their host star.

The observations measured the momentary gradation of starlight as a planet passed its star, called transit.

The researchers found a case in Kepler 1625b that had intriguing anomalies.

Kepler's results were enough for the team to have 40 hours of time with the Hubble telescope to study the planet intensively, obtaining data four times more accurate than Kepler's.

The researchers monitored the planet before and during its 19-hour transit through the star's face.

At the end of the conference, Hubble detected a much smaller second decrease in starlight brightness 3.5 hours later, which corresponds to "a moon tracking the planet like a dog following its owner in leave, "said Kipping.

In addition to this drop in light, Hubble has provided evidence to support the moon's hypothesis by measuring that the planet had begun its transit 1.25 hours earlier than expected.

This is consistent with the planet and the moon orbiting a common center of gravity (center of gravity) that would rock the planet relative to its predicted location.

The researchers noted that this anomaly could in principle be caused by the gravitational pull of a second hypothetical system planet, although Kepler found no evidence of the existence of additional planets around the star during his four-year mission.

"A companion moon is the simplest and most natural explanation for the second trough of the light curve and the orbital sync deviation." Alex Teachey, a research fellow in astronomy at Columbia University

Artist's view of a hypothetical moon-like Earth around an exoplanet resembling Saturn | Nasa

It is estimated that the moon represents only 1.5% of the mass of its companion planet, itself estimated to be several times that of Jupiter. This value is close to the mass ratio between the Earth and its moon.

However, in the case of the Earth-Moon system and the Pluto-Charon system – the largest of the five known natural satellites of the dwarf planet Pluto – it is assumed that an early collision with a larger body would have projected fused materials in a moon.

However, Kepler 1625b and its satellite are gaseous and non-rocky. Therefore, such a collision can not lead to the condensation of a satellite.

This is a catcher

Exomoons are hard to find because they are smaller than their planet and their transit signal is therefore weak. They also changed position with each passage because the moon gravitated around the planet, researchers said.

Moon or planet? The hunt for the exomoon continues | Nasa / JPL-Caltech

In addition, the ideal candidate planets hosting moons are in large orbits, with long and infrequent transit times.

In this research, the moon of Neptune's size would have been among the easiest to detect because of its large size, they said.

(PTI entries)

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