NASA and researchers from Osaka University claim that planets may exist in the Milky Way's bulge. Researchers said that planets in these stellar settings might lead to a better understanding of how planets originate and the universe's history of planet creation.

Study lead author Naoki Koshimoto said in a SpaceRef report that stars in the bulge area are older and considerably closer together than stars in the solar neighbors.

Researchers published their study, titled "No Large Dependence of Planet Frequency on Galactocentric Distance," in The Astrophysical Journal Letters.

Gravitational Lensing to Help Detect Planets

Researchers from Osaka University and NASA utilized a mix of observations and simulation to estimate how the likelihood of a planet-hosting a planet varies with distance from the Galactic center.

The findings were based on a phenomenon known as gravitational microlensing, in which planets serve as lenses, bending and amplifying the light from far away stars. From the Galactic disk to the Galactic bulge-our Galaxy's core region-this effect may be utilized to locate frigid planets akin to Jupiter and Neptune throughout the Milky Way.

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(Photo: Wikimedia Commons)
Milky Way seen from Bolivian High Altiplano, Reserva Nacional de Fauna Andina Eduardo Avaroa

Study co-author Daisuke Suzuki said in a Phys.org report that the only technique to study the planets in the Milky Way is to use gravitational microlensing. However, he noted that nothing is known about planets that are more than 10,000 light-years from the Sun since calculating their distance is challenging.

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 Sci-News said they the distribution of a quantity that describes the relative lens speed and the distance of the light source in planetary microlensing. The study team was able to deduce the Galactic distribution of planets by comparing the distribution seen in microlensing events with that anticipated by a Galactic model.

The findings demonstrate that the distribution of planets is not substantially influenced by their distance from the Galactic center. On the other hand, cold planets orbiting distant from their stars appear everywhere in the Milky Way. This includes the Galactic bulge, a slightly different environment than the solar neighborhood.

Researchers will then integrate these findings with microlens parallax or lens brightness measurements, two additional key planetary microlensing parameters.

Microlensing Reveal More Free-Floating Planets Alone in Deep Space

Meanwhile, Physics World said another international team of astronomers found plausible evidence for four Earth-sized planets roaming freely through interstellar space through gravitational microlensing.

Astronomers believe that the gravitational pull of giant planets may have driven their smaller planetary neighbors out into interstellar space in some star systems. These "free-floating planets" (FFPs) would be tricky to find without the usual exoplanet hunting techniques but should be detected via gravitational microlensing.

This effect happens when a large object passes in front of a more distant star in our line of sight, as predicted by Einstein as part of his theory of general relativity. A short explosion in brightness is noticed as the object's gravitational field bends more of the star's light towards us. These bursts would be exceedingly weak and last little more than an hour in the case of Earth-sized FFPs.

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