the extrasolar planet The Khufu mission revealed that an exoplanet orbiting its star in one day has a distorted shape that looks more like a rugby ball than a sphere. This is the first time that the distortion of an exoplanet has been detected, providing new insights into the internal structure of these star-embracing planets.
The planet known as WASP-103b is located in the constellation Hercules. It is distorted by strong tidal forces between the planet and its parent star WASP-103, which is about 200 degrees hotter and 1.7 times larger than the Sun.
pull the tide
We experience tides in the Earth’s oceans, mainly because the moon is dragging quite a bit over our planet as it orbits around us. The Sun also has a small but significant effect on tides, but it is too far from Earth to cause major disruptions to our planet. The same can’t be said of WASP-103b, a planet nearly twice its size Jupiter With its mass 1.5 times, it orbits its parent star in less than a day. Astronomers suspected that such a short distance would lead to superstorms, but so far they haven’t been able to measure it.
Khufu reveals an exoplanet in the shape of a rugby ball. Credit: ESA
Using new data from the European Space Agency’s Khufu Space Telescope, along with data already obtained NASA/ which and which of them Hubble Space Telescope Using NASA’s Spitzer Space Telescope, astronomers have now been able to discover how the tidal forces of exoplanet WASP-103b warp from an ordinary sphere to the shape of a rugby sphere.
Khufu measures the transit of an exoplanet – the occurrence of light occurs when a planet passes in front of its star from our point of view. Studying the shape of the light curve usually reveals details about the planet, such as its size. Khufu’s high accuracy combined with its guidance flexibility, which allows the satellite to return to the target and track multiple transits, allowed astronomers to detect the exact signal from the WASP-103b tidal distortion. This distinctive signature can be used to reveal more about the planet.
“It’s incredible that Khufu was able to detect such a small deformation,” said Jacques Lascar of the Paris Observatory, Paris University of Sciences and Letters, and co-author of the study. “This is the first time that such an analysis has been done, and we can hope that observations over a longer period of time will reinforce this observation and lead to a better understanding of the planet’s internal structure.”
puffy planet
The team was able to use the WASP-103b light transit curve to derive a variable – the love number – that measures how mass is distributed within the planet. Understanding how mass is distributed can reveal details about a planet’s internal structure.
“The resistance of a material to deformation depends on its composition,” explains Susana Barros of the Institute of Astronomy and the University of Porto in Portugal and lead author of the study. “For example, here on Earth we have tides due to the Moon and the Sun, but we can only see tides in the ocean. The rocky part doesn’t move much. By measuring how deformed the planet is, we can see how rocky, gaseous or watery it is.”
The love number for WASP-103b is similar to that of Jupiter, initially indicating that the internal structure is similar, although WASP-103b has a double radius.
“Basically, we would expect a planet 1.5 times more massive than Jupiter to be about the same size, so WASP-103b must be very bloated due to its star’s warming and possibly other mechanisms,” Susanna said.
“If we can confirm the details of its internal structure through future observations, we may be able to better understand why it is magnified. Knowing the size of this exoplanet’s core will also be important to better understanding how it formed.”
Since the uncertainty in the Loews number is still very large, future observations using the Khufu telescope and the James Webb Space Telescope (WEB) will be needed to decipher the details. Webb’s very high resolution will improve tidal measurements of the outer planets, allowing a better comparison of the so-called “hot Jupiters” and the giant planets of the solar system.
mysterious movement
Another mystery also surrounds WASP-103b. Tidal interactions between a star and a planet very close to the size of Jupiter typically shorten the planet’s orbital period, bringing it closer and closer to the star before the parent star finally swallows it. However, WASP-103b measurements seem to indicate that the orbital period may be increasing and the planet is slowly drifting away from the star. This may indicate that something other than tidal forces is the dominant factor affecting the planet.
Susanna and her colleagues considered other possible scenarios, such as the effect of the host’s companion star on the system’s dynamics or the planet’s slightly elliptical orbit. They could not confirm or rule out these scenarios. It’s also possible that the orbital period is actually decreasing rather than increasing, but only additional observations of WASP-103b’s transits with Khufu and other telescopes will help shed light on this mystery.
“The magnitude of the effect of the tidal shift on the exoplanet’s time-light curve is very small, but thanks to Khufu’s very high resolution, we can see this for the first time,” said Kate Isaacs, EU Khufu Project scientist. space agency. . “This study is an excellent example of the broad questions that exoplanet scientists can answer with Khufu, illustrating the importance of this flexible follow-up mission.”
Reference: “Detectie van getijvervorming van WASP-103b bij 3°C met behulp van CHEOPS” SCC Barrosg, B. Akinsanmi, G. Boué, AMS Smith, J. Laskar, S. Ulmer-Moll, J. Lillo-Box, Dr . Queloz, A. Collier, Cameron, S. J. Souza, de Ehrenreich, M. J. Hutton, J. Bruno, B.-O. Demore, ACM Korea, ODS Demangon, TJ Wilson, A. Bonfante, S. Hoyer, Y Alibert, R. Alonso, J. Anglada Escudi, De Barbato, T. Barzi, De Parado, W. Pomjohan, M. Beck, T. Beck, W. Davies, M. Deloile, A. Dellin, L. Delieris, A. Erickson, AK Heng, L. Case, A. Lecavelier d’Etang, M. Lindell, C. Loves, de Magrain, V. Nascimbeni, PFL Maxted, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, H. Parvainen, J. Peter, G. Bioto, de Polaco, R. Ragazzoni, N. Rando, H. Rower, I. Ribas, N.C. Santos, J.; M. Szabó, N. Thomas, S. Udry, B. Ulmer, V. Van Grotel en NA Walton, 11 januari 2022, Astronomy and astrophysics.
DOI: 10.1051 / 0004-6361 / 202142196
