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The Secret of Stars: Why Do Most Stars Have Planets?
In the vast universe, the existence of stars provides an ideal environment for the formation of planets. As the exploration of the universe deepens, scientists have discovered that almost all stars are accompanied by planets. According to the study, on average, almost every star has at least one planet. The properties of these planets and their relationship to stellar characteristics is one of the important topics that astronomers are currently working hard to unravel.
Proportion of stars with planets
As for the proportion of all stars that have planets, current research shows that the number is likely to be quite astonishing. Although the exact number cannot be determined due to the technical limitations of detecting distant exoplanets, studies have shown that about one in five Sun-like stars has an Earth-sized planet in the habitable zone.
"Stars orbiting planets is the rule, not the exception."
Scientists detect planets using the radial velocity method and the transit method, which are most sensitive to large planets in small orbits. Therefore, most of the exoplanets we know about today are so-called "hot Jupiters", that is, planets with large mass and short orbital periods. According to a 2005 survey, about 1.2% of Sun-like stars host hot Jupiters, while about 3% to 4.5% of Sun-like stars may host giant planets with masses equivalent to at least 30 Earths.
Stellar types and spectral classification
Most of the exoplanets known so far orbit main-sequence stars similar to our Sun, primarily of the F, G, and K spectral classes. Although some lower-mass stars, such as red dwarfs, have a lower probability of detecting planets, the Kepler Space Telescope has still discovered many planets around red dwarfs.
"When very massive stars form planets, they will produce a photoevaporation effect, which will inhibit the formation of planets."
In addition, according to research, about one-sixth of stars with a mass twice that of the sun have one or more Jupiter-sized planets, and among red dwarfs, about one in three red dwarfs orbits them. of long-period Neptune-sized planets. We know from Kepler observations that the rate at which planets appear increases as a star cools and grows in mass.
The influence of metallicity
The metallicity of a star, that is, the content of heavy elements, is closely related to the formation of planets. The study shows that the probability of high-metallicity stars having planets, especially giant planets, is much higher than that of low-metallicity stars. This shows that metallicity plays a vital role in the process of planet formation.
"Asteroids are three times more common in stars with higher metallicity than in stars with lower metallicity."
According to a 2014 study, increased metallicity will increase the occurrence rate of various types of planets, especially the formation of large planets benefits from an environment with higher metal content.
Planets in Multiple Systems
The multiplicity of a star also affects planet formation. According to the study, the multiplicity of red dwarfs is about 25%, while the multiplicity of Sun-like stars is about 45%. This means that during the formation of planets, the environment surrounding the star will have an impact on the stability of the planetary system. Dozens of planets are known to orbit binary star systems, such as 55 Cancri, which may prove that planets can form not only around single stars, but also in multiple systems.
Open star cluster and planet discovery
Open star clusters are major sites of star formation, but relatively few planets have been found in these environments. Some studies have suggested that this may be because the environment of open star clusters hinders the formation of planets. Recent discoveries have confirmed that the existence rate of planets in open star clusters is similar to that of stars outside the field. Two planetary systems have been discovered in N cluster 6811.
With the advancement of technology, we will be able to observe and classify exoplanets more accurately in the future, and gain a deeper understanding of the formation process of planets and their relationship with stars. When we look up at the night sky, are we in awe of how many unknown planets are lurking among those lonely stars?
