A Newborn Hot Neptune Discovered Near One Of The Closest Stars To Earth
At the red dwarf in the constellation of the Microscope, astronomers found a newborn planet similar in size and properties to Neptune. This is the first known planet of its kind in the immediate vicinity of Earth. A description of their work was published in the scientific journal Nature.
"The AU star in the constellation of the Microscope is relatively small. It is about half the size of the Sun. Such luminaries are very active due to powerful magnetic fields. This may explain why it took almost 15 years to discover the planet in its vicinity," said one of the authors of the discovery, a planetary scientist from the University of Montreal (Canada) Jonathan Gagnier.
The AU Microscopii star began attracting the attention of scientists in 2003. Then astronomers received the first photos of it and found that it was a newly formed star located at a distance of about 32 light-years from Earth. Interest in it is since this newborn red dwarf still surrounds a disk of gas and dust, turned to us in "profile."
Thanks to this, scientists can monitor how its shape changes over time, as well as determine the nature of the movement of matter in it. For example, five years ago, European astronomers discovered that the surface of this disk is constantly moving waves, the existence of which was not predicted by the theory of the formation of stars and planets.
There were a lot of flares and spots on the surface of AU Microscopii, so astronomers could not search for traces of planets in its vicinity using the traditional transit technique. Its essence is that when a planet rotates around a star and passes between it and the observer, the brightness of the luminary predictably decreases. This is a good way to look for exoplanets in stars similar to the Sun, but in the case of red dwarfs, it is easy to mistake a flash or spot for a planet.
Gagnier and his colleagues circumvented these problems by using infrared telescopes. With their help, scientists watched not for periodic decreases in the brightness of the star, but for how the structure of its spectrum changed. The presence of planets can be determined by characteristic shifts in the position of spectral lines. These shifts are because gravitational interactions between the Sun and its satellites lead to small but noticeable changes in the position of the star in space.
A few years after such observations began on the ground-based IRTF telescope, Canadian astronomers found several hints of the existence of at least one planet in the vicinity of AU Microscopii. However, the accuracy of their data was too low to say for sure.
The scientists obtained additional data using two NASA orbiting observatories – the Tess optical telescope, designed to search for planets using the transit method, and the Spitzer infrared Observatory. By combining ground-based and space-based observations, Gagnier and his colleagues not only confirmed the existence of a planet in AU MIcroscopii but were also able to study its properties.
In particular, it turned out that this planet is one of the so-called "hot Neptunes" - worlds that are similar in size and properties to the gas giant of the same name in the Solar system but are located much closer to their star.
In particular, the planet AU Microscopii b makes one revolution around a red dwarf in just nine incomplete days, and its mass is about 50 times that of earth and five times less than that of Jupiter. It is located inside the gas-dust disk that surrounds the red dwarf. Scientists suggest that this is why it was not possible to find it for so long.
The discovery of this planet, according to Gagnier, was particularly important for scientists, because previously astronomers had never found new planets in the vicinity of nearby stars. Thanks to this, in the future it will be possible to study the atmosphere and other properties of AU Microscopii b in detail, which will allow astronomers to test many theories of the formation of gas giants and earth-like planets and their interaction with the protoplanetary disk.