The masses of the giant planets of the V1298 Tau system, which is only 20 million years old, have been measured by an international team of scientists, including researchers from the Instituto de Astrofísica de Canarias (IAC) and other institutions from Spain, Italy, Germany, Belgium, the United Kingdom, and Mexico.
The masses of such young giant planets had never been determined before, and this is the first proof that they had already attained their final size at such an early point in their existence.
For this study they have used radial velocity measurements from the HARPS-N spectrographs, at the Roque de los Muchachos Observatory (ORM), and CARMENES, at the Calar Alto Observatory. The results are published today in the journal Nature Astronomy.
The study, led by the IAC researcher Alejandro Suárez Mascareño, reports the measurement of the masses of two giant planets that orbit the young solar-type star V1298 Tau. They were discovered in 2019 by a team lead by Trevor David (JPL) using data from NASA’s Kepler space telescope, which allowed the measurement of their sizes, slightly smaller than Jupiter, and of their orbital periods, 24 and 40 days for V1298 Tau b and e, respectively.
“The characterization of very young planets is extraordinarily difficult,” says Alejandro Suárez Mascareño, first author of the publication. “The parent stars have very high levels of activity and until very recently it was unthinkable to even try.”
And he adds: “Only thanks to the combination of detections made with space telescopes, combined with intense radial velocity campaigns from Earth-based observatories and the use of the most advanced analysis techniques, it was possible to begin to see what is happening in such early stages of the evolution of planetary systems.”
For many years, theoretical models have indicated that giant planets begin their evolution as bodies with a larger size, and later they contract over hundreds millions or even billions of years.
Víctor J. Sánchez Béjar
In reality, for the new planetary mass estimations, it was essential to isolate the signals generated by these planets from the nearly ten-fold greater signal provided by the star’s activity.
The planets V1298 Tau b and c have masses and radii that are strikingly similar to those of large planets in our Solar System or in other old extra-solar systems, according to the research. These measurements, which are the first of their kind for such young giant planets, allow us to put existing theories regarding planetary system formation to the test.
“For many years, theoretical models have indicated that giant planets begin their evolution as bodies with a larger size, and later they contract over hundreds millions or even billions of years,” explains Víctor J. Sánchez Béjar, researcher at the IAC and co-author of the work.
“We now know that they can actually reach a size similar to that of the planets in the Solar System in a very short time,” he notes.
Researchers can learn a lot about what happened when our solar system was young by studying young systems.
“We still do not know if V1298 Tau is a normal case and its evolution is similar to that of most planets or if we are facing an exceptional case; if this were the normal scenario, it would mean that the evolution of planets like Jupiter and Saturn could have been very different from what we think,” comments Nicolas Lodieu, a researcher at the IAC and also a co-author of the work.
As a result, the findings of this research contribute to a better understanding of the early evolution of planetary systems like ours.
The work needed a large observational effort as well as the participation of several observatories and institutions from various nations in order to estimate these masses.
It was necessary to combine radial velocity measurements from various instruments, including the high-resolution HARPS-N ultrastable spectrograph, installed at the Telescopio Nazionale Galileo (TNG) at the Roque de los Muchachos Observatory; the CARMENES high resolution spectrograph, installed at the Calar Alto observatory; the HERMES spectrograph, installed on the Mercator telescope, also at the ORM; and the SES
Observations from the Las Cumbres Observatory, a global network of telescopes, have been utilized to continuously monitor the fluctuations in the star’s activity.
In addition to the researchers Alejandro Suárez Mascareño, Victor J. Sánchez Béjar and Nicolas Lodieu, from the IAC researchers Rafael Rebolo López, Felipe Murgas, Jonay González Hernández, Carlos Cardona Guillén, Borja Toledo Padrón, Patricia Chinchilla, Emma Esparza Borges, Mahmoud Oshagh, Enric Pallé and Hannu Parviainen.
