Artistic impression of WASP-103b and its host star. Credit: ESA
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The planet, known as WASP-103b, is located in the constellation Hercules. It has been distorted by the strong tidal forces between the planet and its host star WASP-103, which is about 200 degrees hotter and 1.7 times more massive than the Sun.
tidal pull
We experience ups and downs in Earth’s oceans mainly because the Moon drags slightly on our planet as it orbits around us. The sun also has a small but significant influence on tides, but is too far from Earth to cause major distortions on our planet. The same cannot be said about WASP-103b, a planet nearly twice the size
Khufu reveals an exoplanet shaped like a rugby ball. Credit: ESA
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Using new data from the European Space Agency’s Khufu Space Telescope, together with previously obtained data
Khufu measured the transit of an exoplanet – the dip in light occurs when a planet passes in front of its star from our perspective. Studying the shape of the light curve usually reveals details about a planet, such as its size. Cheops’ high accuracy combined with its guidance flexibility, which allows the satellite to return to the target and monitor multiple transits, allowed astronomers to detect the precise signal of WASP-103b’s tidal distortion. This signature signature can be used to reveal more about the planet.
“It’s remarkable that Khufu can actually detect such a small deformation,” said Jacques Lascar of the Paris Observatory, Paris University of Science and Letters, and co-author of the study. “This is the first time such an analysis has been carried out, and we can hope that observations over a longer period of time will enhance these observations and lead to better knowledge of the planet’s internal structure.”
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windblown 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 the planet’s internal structure.
“A material’s resistance to deformation depends on its composition,” explains Susana Barros of the Institute for Astronomy and the University of Porto, Portugal, and lead author of the study. “For example, on Earth we experience tides due to the moon and sun, but we can only see the tides of the ocean. The rocky part doesn’t move much. By measuring how deformed the planet is, we can tell how much rock it is. , gaseous or aqueous.”
The love numbers for WASP-103b are similar to those of Jupiter, which initially indicated that the internal structure was similar, even though WASP-103b had twice the radius.
“In principle, we expect a planet 1.5 times the mass of Jupiter to be roughly the same size, so WASP-103b should be very swollen due to its stellar heating and other possible mechanisms,” Susanna said.
“If we can confirm the details of its internal structure through future observations, perhaps we can better understand what makes it so elevated. Knowing the size of this exoplanet’s core is also important for better understanding how it formed.”
Since the uncertainty of Love’s number is still very high, future observations using the Khufu telescope and the James Webb Space Telescope (WEB) will be required to decipher the details. Webb’s extremely high resolution will improve measurements of the exoplanet’s tidal deformation, allowing for better comparisons between these so-called “hot Jupiters” and the solar system’s giant planets.
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mysterious move
Another mystery also shrouds WASP-103b. Tidal interactions between stars and planets that are very close to Jupiter’s size will usually shorten the planet’s orbital period, bringing it closer to the star before the parent star eventually engulfs it. However, WASP-103b’s measurements seem to indicate that the orbital period may be increasing and the planet is slowly moving away from the star. This may indicate that something other than tidal forces is the dominant factor influencing the planet.
Susanna and her colleagues considered other possible scenarios, such as the impact of the host companion star on the dynamics of the system or the slightly elliptical orbit of the planet. They couldn’t confirm this scenario, but they couldn’t rule it out either. It’s also possible that the orbital period is actually decreasing, not increasing, but that only additional observations of WASP-103b’s transit with Khufu and other telescopes will help shed light on this mystery.
“The magnitude of the effect of tidal distortion on the exoplanet’s transient light curve is very small, but thanks to Khufu’s very high resolution, we are able to see this for the first time,” said Kate Isaac, Khufu project scientist at the European Space Agency. . “This study is an excellent example of the very diverse questions that exoplanet scientists can answer with Khufu, illustrating the importance of this flexible follow-up mission.”
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Referensi: “Deteksi deformasi pasang surut WASP-103b pada 3 °C menggunakan CHEOPS” oleh SCC Barrosg, B. Akinsanmi, G. Boué, AMS Smith, J. Laskar, S. Ulmer-Moll, J. Lillo-Box, D . Queloz, A. Collier Cameron, S. G. Sousa, D. Ehrenreich, M. J. Hooton, G. Bruno, B.-O. Demore, ACM Korea, ODS Demangeon, T. G. Wilson, A. Bonfanti, S. Hoyer, Y. Alibert, R. Alonso, G. Anglada Escudé, D. Barbato, T. Bárczy, D. Barrado, W. Baumjohann, M. Beck, T. Beck, W. Davies, M. Delwell, A. Dillin, L. Delries, A. Erickson, A. K. Heng, L. Kiss, A. Lecavelier des Etangs, M. Lendl, C. Lovis, D. Magrin, V. Nascimbeni, PFL Maxted, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, H . Parviainen, G. Peter, G. Piotto, D. Pollacco, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, M. Steller, Gy. M. Szabó, N. Thomas, S. Udry, B. Ulmer, V. Van Grotel dan N. A. Walton, 11 Januari 2022, Astronomy and astrophysics.
DOI: 10.1051 / 0004-6361 / 202142196
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