Cold Planets Exist Throughout the Galaxy– in the Galactic Lump
Researchers led by Osaka University and NASA found that the distribution of cold “planets” in the Galaxy is not highly based on the range from the Galaxy center.
Although countless planets have been discovered in the Galaxy, many stay much less than some thousand light-years from Earth. However, our Galaxy is more than 100,000 light-years across, making it challenging to examine the Galactic distribution of worlds. Now, a research group has discovered a means to subdue this obstacle.
In a research published in The Astrophysical Journal Letters, scientists led by Osaka University and NASA have utilized a mixture of observations and modeling to identify precisely how the planet-hosting likelihood varies with the distance from the Galactic center.
These observations were based on a phenomenon called gravitational microlensing, where objects such as planets work as lenses, bending and multiplying the light from distant stars. This effect can be used to discover cold planets like Jupiter and Neptune across the Milky Way, from the Galactic disk to the Galactic lump– the central area of our Galaxy.
” Currently, gravitational microlensing provides the only means to investigate the distribution of planets in the Milky Way,” states Daisuke Suzuki, co-author of the research. “However, until now, little is known mostly due to the challenge in determining the distance to worlds that over than 10,000 light-years away from the Sun.”
To fix this issue, the researchers considered the distribution of a quantity that depicts the lens’s relative motion and remote light source in planetary microlensing. By rivaling the distribution observed in microlensing events with that prognosticated by a Galactic model, the research study team could infer the Galactic distribution of planets.
The results reveal that the planetary distribution is not heavily dependent on the range from the Galactic center. Instead, cold planets orbiting far from their stars appear to exist all over the Milky Way. Including the Galactic bulge, which has a highly different setting to the solar neighborhood, and where the existence of planets has long been uncertain.
” Stars in the bulge area are older and much closer to each other than stars in the solar neighborhood,” clarifies the lead author of the study Naoki Koshimoto. “Our discovery that planets stay in both of these stellar environments can bring about a better understanding of exactly how planets are formed as well as the history of planet formation in the Galaxy.”
According to the scientists, the following action should be to incorporate these results with dimensions of microlens parallax or lens illumination– two other vital quantities related to planetary microlensing.
Originally published on Sciencedaily.com. Read the original article.
Reference: “No Large Dependence of Planet Frequency on Galactocentric Distance” by Naoki Koshimoto, David P. Bennett, Daisuke Suzuki and Ian A. Bond, 26 August 2021, The Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/ac17ec
