press release
July 19, 2023
Astronomers have used the Atacama Large Millimeter/submillimeter Array (ALMA) to discover a possible “sister planet” orbiting a distant star. The team has detected a cloud of debris that could share an orbit with the planet. They believe it is the building blocks of a new planet or the remains of a planet that has already formed. If confirmed, the discovery would be the strongest evidence yet that two exoplanets can share an orbit.
“Twenty years ago, it was theoretically predicted that pairs of planets with similar masses could have the same orbit around their star, called Trojan or co-orbital planets. For the first time, we have found evidence that supports this idea.says Olga Balsalobre-Ruza, a student at the Center for Astrobiology in Madrid, Spain, who presented today at Astronomy and astrophysics study published.
Trojans, rocky bodies in the same orbit as a planet, are common in our own solar system. (1). The most famous example is Jupiter’s Trojan asteroids – more than 12,000 rocky bodies in the same orbit around the Sun as the gas giant. Astronomers have predicted that Trojans, particularly Trojan planets, might exist around a star other than our Sun, but there is little evidence that they exist.Exotroyans (Trojan planets located outside the solar system) look like unicorns: in theory, they could exist, but no one has ever discovered them.says co-author Jorge Lillo-Box, principal investigator at the Center for Astrobiology.
Now, thanks to ALMA, in which ESO is involved, an international team of scientists has found the strongest observational evidence to date for the existence of Trojan planets – in the system PDS70. This young star is known to host two giant Jupiter-like planets, PDS 70b and PDS 70c. When analyzing archives ALMAObservations of this system allowed the team to discover a debris cloud at the location in PDS 70 b’s orbit where Trojan horses are suspected.
The Trojans are located in two so-called Lagrangian zoneslarge regions of a planet’s orbit where the combined gravitational pull of the star and planet can trap material. Examining these two areas in PDS 70 b’s orbit, astronomers found a faint signal suggesting that there might be a debris cloud there with a mass about twice that of our moon.
The team believes this debris cloud could indicate a pre-existing Trojan world in this system or a planet in the process of forming.Who could imagine two worlds sharing the length of the year and the conditions of habitability? Our work is the first evidence that such a world could exist.said Balsalobre-Ruza.We can imagine that a planet could share its orbit with thousands of asteroids, as in the case of Jupiter, but I find it disconcerting that planets could share the same orbit.“
“Our research represents a first step in the search for co-orbital planets at a very early stage of their formation.says co-author Nuria Huélamo, senior scientist at the Center for Astrobiology.This raises new questions about the origins of Trojan horses, their evolution and their frequency in different planetary systems.” adds Itziar De Gregorio-Monsalvo, head of the ESO scientific office in Chile, who also participated in this research.
To fully confirm their discovery, the team will have to wait until after 2026. They then want to use ALMA to check whether PDS 70 b and its debris cloud are moving significantly in their shared orbit around the star.This would be a step forward in the field of exoplanets.said Balsalobre-Ruza.
“The future of this topic is very exciting and we look forward to the expanded capabilities of ALMA planned for 2030, which will greatly improve the network’s ability to characterize Trojans in many more stars.», concludes De Gregorio-Monsalvo.
Endnotes
(1) When asteroids in Jupiter’s orbit were discovered, they were named in their honor. Hero of the Trojan Warwhich gave rise to the name Trojan horse for these objects.
More information
This research was presented in an article published in Astronomy & Astrophysics.
The team is composed of O. Balsalobre-Ruza (Centro de Astrobiología (CAB), CSIC-INTA, Spain), I. De Gregorio-Monsalvo (European Southern Observatory (ESO), Chile), J. Lillo-Box (CAB ), N. Huélamo (CAB), Á. Ribas (Institute of Astronomy, University of Cambridge, United Kingdom), M. Benisty (Laboratoire Lagrange, Université Côte d’Azur, CNRS, Observatoire de la Côte d’Azur, France and Univ. Grenoble Alpes, CNRS, IPAG, France), J. Bae (Department of Astronomy, University of Florida, USA), S. Facchini (Dipartimento di Fisica, Università degli Studi di Milano, Italy) and R. Teague (Department of Earth, Atmospheric and Environmental Sciences planets, Massachusetts Institute of Technology). , UNITED STATES).
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Contact details
Olga Balsalobre-Ruza
Doctoral student at the Astrobiology Center (CAB, CSIC-INTA)
Madrid, Spain
Tel: +34 918131531
E-mail: obalsalobre@cab.inta-csic.es
Itziar De Gregorio-Monsalvo
ESO Head of Office for Science Chile
Santiago, Chile
Tel: +56 (2) 2463 3000
E-mail: idegrego@eso.org
Jorge Lillo box set
Researcher at the Center for Astrobiology (CAB, CSIC-INTA)
Madrid, Spain
Tel: +34 918131309
E-mail: jorge.lillo@cab.inta-csic.es
Nuria Huélamo Bautista
Researcher at the Center for Astrobiology (CAB, CSIC-INTA)
Madrid, Spain
Tel: +34 918131530
E-mail: nhuelamo@cab.inta-csic.es
Barbara Ferreira
ESO Media Manager
Garching near Munich, Germany
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Mobile: +49 151 241 664 00
E-mail: press@eso.org
Markus Nielbock (press contact Germany)
ESO Science Outreach Network and House of Astronomy
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This is a translation of ESO press release eso2311.