What would happen if you put an Earth-sized planet in close orbit around an M dwarf (red dwarf) star? This question is more than an academic question because M dwarfs are among the most abundant stars we know. A group of researchers, by examining a planet called GJ 1252b, reached an answer to the above question, which is not very interesting.
Since this planet is in an orbit close to its star, it receives a lot of heat; But this proximity is fatal in another way. According to Michelle Hill, an astrophysicist at the University of California Riverside and co-author of a paper on GJ 1252b:
The pressure from the star’s radiation is so strong that it can destroy the atmosphere of a planet.
The mentioned planet is located at a distance of 65 light-years from the Earth and completes its star orbit every 24 Earth hours. The heat from the star has made this planet uninhabitable.
Visualization of the destruction of the planet’s atmosphere in the vicinity of its star
Such conditions are not much different from the conditions of Mercury in the solar system. There is no atmosphere and the planet heats and cools repeatedly as it orbits the sun. In fact, even the earth loses a small part of its atmosphere due to solar activity.
However, volcanic activities and other events cause gases to return to the earth’s atmosphere. Earth is a lucky planet; But planets like Mercury and GJ 1252b are not so lucky, and this difference will have important implications for the search for life on habitable worlds.
dwarf star M What is?
In the Milky Way alone, millions upon millions of M dwarf stars (red dwarf) exist. The size of these stars varies from one-tenth to two-thirds of the mass of the Sun. These stars can be active and emit flares and eruptions into their systems. Most of these stars have at least one planet in their life belt and the other planets are at different distances from them.
Searching for life on planets around red dwarfs is difficult. Stellar activity removes much of the atmosphere and any chance for life to grow on such planets. Since M dwarfs are so abundant, the search for life on planets with high habitability potential becomes difficult. In general, there is no interesting news about planets like GJ 1252b. Hills says:
This planet’s condition may bode well for other planets around red dwarfs, even if they are further away from their star. In any case, the search should continue with the James Webb Space Telescope, which looks at such planets.
Even if M dwarfs are killers of planetary atmospheres, one should not despair. For example, many of the 5,000 stars in the vicinity of Earth are M dwarfs. Even if many of these stars turn their planets into uninhabitable worlds, at least 1,000 stars (not all of which are M dwarfs) can support life on their worlds. Hill believes:
If a planet is far enough from an M dwarf, it can retain its atmosphere. It is not yet possible to conclude with certainty that all the rocky planets around these stars have suffered the fate of Mercury. So I remain optimistic.
Searching for atmosphere GJ 1252b
The position of GJ 1252b and its scientific evidence are fascinating. Astronomers used data from the Spitzer Space Telescope to estimate the planet’s infrared radiation based on the blocking of starlight. According to the findings, the stellar rays covered the planet. The surface temperature of the planet during the day is approximately 1227 degrees Celsius. The temperature that is enough to melt gold, silver and copper.
This heat, due to the low pressure, led scientists to conclude that the said planet has no atmosphere; If this planet had a carbon dioxide atmosphere, it would trap the heat of the surface and cover the surface of the planet like a blanket. However, the planet GJ 1252b is not so lucky. Stephen Kane, an astrophysicist at UCR and one of the authors of this research, says:
Even if the planet GJ 1252b had 700 times as much carbon as Earth, there would still be no trace of an atmosphere. It was possible that there was an atmosphere in the beginning; But eventually it would disappear.
If the aforementioned research is true for a set of M dwarfs, the search for life and habitable planets will be directed to worlds located around more stable stars.