Billions Of ‘Undetected’ Rogue Exoplanets May Exist Throughout Our Galaxy


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Observations of the universe have so far revealed that most alien worlds out there are formed in solar systems similar to ours.

Given the fact that there’s a certain ‘rule’ in the placement of our solar system; we have the sun, the inner planets which are rocky, and outer planets which are gaseous, we believe planets elsewhere are also neatly ordered in systems just like outs.

However, astronomers have found there’s no such rule, and those rogue planets, alien worlds not orbiting any known star or system exists, drifting alone through the galaxy.

Rogue Worlds

And while we have found thousands of planets outside our solar system to date, astronomers have only been able to spot a few of them which are not orbiting any known star. They are drifters. Lone travelers.

But there’s a discrepancy between the number of planets we’ve discovered to date and the number which don’t orbit any known star.

That’s why a new research paper suggests that many more undetected rogue planets may exist.

In the new paper, scientists have revealed that simulations suggest there could be ‘BILLIONS’ of rogue planets in the milky way alone.

Detecting them is a hard thing to do.

Most of the exoplanets we’ve discovered elsewhere in the cosmos were found using two main detection methods.

One of them is the radial velocity method by which astronomers detect the planet’s gravitational effect on its host star.

The other is the transit method. It allows astronomers to spot an exoplanet as it orbits in front of the star causing it to dim, changing its brightness.

But both of these methods need a starĀ for astronomers to discover any exoplanets.

So, what can we do to spot planets that don’t orbit any stars?

Well, last year it has been reported that two rogue exoplanets were spotted by astronomers thanks to the way their gravity bends the light that is being emitted from behind them.

Infrared imaging has allowed astronomers to find outer rogue exoplanets.

However, until now no more than 20 rogue planets have been discovered.

Compared to 3,917 confirmed exoplanets orbiting a star, we see a massive discrepancy.

To understand the potential number of rogue planets out there, astronomers at the University of Leiden in The Netherlands ran a series mathematical simulations of the Orion Trapezium, a region in the Orion Nebula home to a cluster of young stars.

In the simulation, astronomers assigned five hundred sun-like stars with four, five, or six planets each, totaling 2,522 planets in the region. They modeled them with masses from around three times that of Earth to around 130 times the mass of Jupiter.

Simulations showed that of the total number of planets, around 16.5 percent of them (357 planets) were expelled from their star systems within 11 million years of forming, becoming cosmic wanderers traveling throughout the galaxy.

Astronomers found that some of the worlds that left their solar system remained within the star cluster. Other star systems eventually captured around five percent of the stars, but around 282 planets escaped the cluster entirely.

The new simulations also revealed that 75 of the 2522 planets ended up crashing into their host stars.

Around 34 planets ended up colliding against another planet.

This has led experts to speculate that rogue planets exist in the same numbers as planets orbiting a star.

Astronomers say that their simulations indicate that there could be at least 16.5 billion rogue planets wandering around the Milky Way Galaxy, all of which belong to a total of around 100 Billion planets, give or take a million.

The new study has been accepted for publication into Astronomy & Astrophysics. The study is available at the pre-print server arXiv.


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