2024-10-08 08:05:09
The view of our galaxy has changed radically since the first planet orbiting a star other than the Sun was discovered in 1995. Since then, a multitude of discoveries have taught us that the stellar environment is full, not only of planets, but of real planetary systems. The number of exoplanets discovered is growing at such a rate that the possibility of finding one similar to Earth, and with some form of life, is no longer a crazy idea.
But where to start the search? It seems logical to think that I should start with the stars closest to the Sun; After all, proximity makes observations from Earth easier. In 2016, a team of researchers discovered an Earth-sized planet located in the habitable zone around Proxima Centauri, the closest star to us. Now it’s the turn of the closest star: Barnard’s Star, located just 6 light years from the Sun. According to an article published in the journal Astronomy & Astrophysics, of which he is the first author Jonay I. González Hernándezresearcher at the Institute of Astrophysics of the Canary Islands (IAC) and our guest a Talk to scientistsan exoplanet three times larger than Mars has been identified around Barnard’s Star and found evidence of three other possible planets.
Barnard’s Star, also known as GJ 699, is a red dwarf, a type of star smaller and cooler than our Sun. Because red dwarfs are the most abundant stars in the galaxy, accounting for about 80% of the stars in the solar neighborhood. important objectives in the search for exoplanets. Being cooler and dimmer than the Sun, their habitable zones are closer to the star, making it easier to locate planets using the radial velocity technique.
Barnard’s Star has been the subject of numerous studies due to its high proper motion, which makes it the star with the greatest apparent motion in the sky. Over the years, various measurements of its stellar activity and variations in its radial velocity have been made to detect planets in its environment. However, early signs of planets around this star, such as the candidate with a period of 233 days proposed in previous studies, have not been confirmed by new observations from EXPRESSEDwhich highlights the importance of having high precision data obtained from this instrument.
EXPRESSED is a high resolution spectrograph installed at the Paranal Observatory THAT in Chile, designed specifically to search for exoplanets using the radial velocity technique. This technique measures small shifts in a star’s spectrum caused by the gravity of an orbiting planet, allowing the presence and characteristics of planets to be inferred.
Between 2019 and 2023, 156 observations of Barnard’s Star were made EXPRESSED. Analysis of these observations revealed several periodic signals that could indicate the presence of low-mass planets in orbits close to the star. In particular, a signal with a period of 3.15 days was identified, confirmed as a planet with a minimum mass equal to 0.37 times that of the Earth, making it a low-mass planet, i.e. sub-Earth. This planet has a mass similar to three times that of Mars, placing it in the category of rare planets. Although this planet lies outside the habitable zone due to its proximity to the star, the data collected reveal signals that could belong to several other planets, a possibility that, if confirmed in future research, would reveal that Barnard’s Star could be surrounded from an entire planetary system with several rocky planets like Earth.
Jonay talks about the enormous research possibilities that will open up in the near future thanks to the construction of large telescopes such as the Extremely Large Telescope (ELT), who will have the tool ANDESdesigned to find other small planets and, perhaps, discover signs of life in other corners of the universe.
We invite you to listen Jonay I. González Hernándezresearcher at the Institute of Astrophysics of the Canary Islands (IAC) and the Department of Astrophysics of the University of La Laguna.
References:
JI González Hernández, A. Suárez Mascareño, AM Silva, AK Stefanov, JP Faria, HM Tabernero, A. Sozzetti, R. Rebolo, F. Pepe, NC Santos, S. Cristiani, C. Lovis, X. Dumusque, P. Figueira, J. Lillo-Box, N. Nari, S. Benatti, M.J. Hobson, A. Castro-González, R. Allart, VM Passegger, M.-R. Zapatero Osorio, V. Adibekyan, Y. Alibert, C. Allende Prieto, F. Bouchy, M. Damasso, V. D’Odorico, P. Di Marcantonio, D. Ehrenreich, G. Lo Curto, R. Génova Santos, CJAP Martins, A. Mehner, G. Micela, P. Molaro, N. Nunes, E. Palle, SG Sousa and S. Udry
A&A, 690 (2024) A79
DOI:
Planetary system in the nearest star. We spoke with Jorge Lillo-Box
Radio signals from Proxima Centauri. We spoke with Miguel Pérez Torres.
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