Observations on the planet HD 209458b made by Telescopio Nazionale Galileo in the Canary Islands show that water, carbon monoxide, hydrogen cyanide, methane, ammonia and acetylene are present in the atmosphere, making its carbon content richer than oxygen. According to the model, this indicates that this distant world is getting closer and closer to its star.
An international team of scientists led by researcher Paolo Giacobbe from the United States Italian National Institute of Astrophysics (INAF), He studied the chemical composition of the atmosphere of planets outside the solar system in an unprecedented way.
Their research is published in the journal natural, Revealing the simultaneous existence for the first time Six chemical components Similar to the water in the atmosphere of Jupiter’s hot planet (water, carbon monoxide, hydrogen cyanide, methane, ammonia and acetylene): HD 209458b, It orbits HD 209458 Pegasus, about 150 light years away from our solar system.
The presence of these molecules indicates that the carbon in the planet’s atmosphere is higher than the carbon in oxygen. This is why according to the author and the current model, HD 209458b was formed at a greater distance from the central star, and later moved to its current position, closer it.
Because of the observation with the instrument, the discovery becomes possible GIANO-B installed at Galileo National Telescope (TNG) In Roque de Los Muchachos on La Palma in the Canary Islands, it then combines innovative data analysis techniques.
Telescopio Nazionale Galileo (TNG) operates from Roque de Los Muchachos in La Palma, Canary Islands. / A. Harutyunian-TNG
HD 209458b has a lower density than Jupiter and orbits its star at a distance of slightly more than 7 million kilometers (20 times smaller than the distance between the Earth and the Sun).This makes the planet’s temperature very high 1200°C.
Its orbital period is only 3.5 days, which is conducive to observation of exoplanets with the help of the solar system. Mode of transport. When the planet passes in front of the star, the light from the star is filtered through the atmosphere, which allows us to observe the characteristic traces of the molecules that form the star.
Specifically, the research team collected data during the four planetary journeys of HD 209458b, and used GIANO-B to observe and Near infrared The electromagnetic spectrum.
Transmission spectroscopy allows astronomers to study the composition of planetary atmospheres along a straight line separating the parts illuminated by the stars from the unilluminated parts (called “planets”). Terminator. Thanks to the acquisition of thousands of spectral lines, the spectroscopy performed with GIANO-B made it possible for the first time to simultaneously identify six molecules in the atmosphere of HD 209458b.
The GIANO-B instrument is installed in the dome of the TNG telescope. / A. Harutyunian -TNG
According to the current theoretical model of exoplanet atmosphere, the discovery of so many molecules in the atmosphere of HD 209458b indicates that carbon is more abundant in atmospheric chemistry than oxygen.
This feature hints at this planet Formed beyond the snow line, Which is a few astronomical units from its central star, and the carbon content in the gas of the protoplanetary disk is expected to be higher.
For comparison with our solar system, the formation range of HD 209458b may be beyond the orbit of Mars, and may be between the orbits of Jupiter and Saturn. Later, it will migrate towards the central star at the distance we observe today, which is one-tenth of the distance between the sun and Mercury.
These results are as INAF Global Planetary System Architecture (gap, In English acronym), to verify the theory that hot Jupiter planets may be formed far greater than their locations.
Paolo Giacobbe and others. “There are five species of carbon and nitrogen in the atmosphere of a huge hot planet.” natural, 2021.