- Paul Rinkon
- Science Editor – BBC Website
Astronomers have discovered signs of what might be the first planet outside our galaxy.
So far, scientists have discovered about 5,000 planets orbiting stars outside our solar system, but they are all located within the Milky Way.
The possible planet where signals were detected by NASA’s lunar telescope is located in the constellation Messier 51.
The galaxy is located 28 million light-years from the Milky Way.
These new results depend on the occurrence of astronomical traffic, when a planet passes in front of a star, blocking some of the star’s light, and this leads to a blur in its luminosity as observed by the telescope.
This common technique has previously been used to locate thousands of planets outside our solar system.
Dr. Roxanne Stefano and his colleagues studied the blurring of X-ray images of a type of object called an X-ray diode.
This object usually consists of a neutron star or a black hole that pulls gas from a partner star. The object closest to the neutron star becomes very hot and glows at the X-ray wavelength.
Because the area where X-rays are emitted is small, the path of a planet in front of it can block most or all of the X-rays, making it easier to observe astronomical traffic.
The team members used this technology to find a possible planet with a binary system called M51-ULS-1.
Dr Di Stefano of the Harvard-Smithsonian Center for Astrophysics in Cambridge, USA, told the BBC: “The method we have developed and used is currently the only method that can be used to detect planetary systems in other galaxies.”
“It is a kind of method, very suitable for detecting planets orbiting X-binary stars, which can measure the optical curve from any distance.
The future of planetary observation
A binary is a black hole or neutron star that orbits a sub-star 20 times the mass of the Sun. A neutron star is a remnant nucleus from a previous massive star.
The astronomical traffic lasted about 3 hours, during which the X-ray emission was reduced to zero. Based on this and other information, astronomers estimated that the probable planet would be the size of Saturn. It orbits a neutron star or black hole at a distance equal to twice the orbit of Saturn orbiting the Sun.
Dr de Stefano said techniques used successfully to detect planets within the Milky Way outside the Solar System could be blocked if used to monitor other galaxies. This is because it reduces the amount of light that can reach the telescope over long distances.
Excess material accumulates in a narrow space (as we see from Earth), making it difficult to verify a star on its own.
The astronomer says that X-rays “only allow the isolation of dozens of sources throughout the entire galaxy, so they can be verified and part of them so bright in X-rays that the light curve within them can be measured.”
“Finally, large X-ray emissions come from a small area that can be largely or completely obscured by a planet’s path.”
The researchers agree that more data is needed to confirm their explanations.
Among the challenges facing research is that the planet’s vast orbit will not interfere with its binary partner again after 70 years, making it impossible to monitor it in close proximity.
Astronomers put forward another explanation, namely that blurring can occur as a cloud of gas and dust passes in front of the X-ray source.
But they rejected this explanation because the properties of the event did not match the elements of the gas cloud.
Julia Princeton of Princeton University in New Jersey said, “We know what’s announced is exciting and bold, so we expect other astronomers to look at it very carefully.
“We believe our evidence is strong and the matter is now up for scientific research,” he added.
New generation optical telescopes and infrared telescopes cannot overcome congestion and fading, so X-ray wavelength monitoring would be the best way to detect planets in other galaxies, Dr. de Stefano said.
But he said another technique called “microlensing” could help detect planets outside our galaxy in the future.
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