천문학자들은 바다 깊숙이 완전히 덮일 수 있는 태양계 밖의 세계를 발견합니다.

외계행성 TOI-1452 b의 기술 번역, 바다 깊이에 완전히 뒤덮일 수 있는 소행성. 크레딧: Benoit Gougeon, 몬트리올 대학교

캐나다에서 부분적으로 설계된 장비의 도움으로 천문학자 팀은 다음을 발견했습니다.[{” attribute=””>exoplanet that could be completely covered in water.

An international team of scientists has announced the discovery of TOI-1452 b, an exoplanet orbiting one of two small stars in a binary system located in the Draco constellation about 100 light-years from Earth. The researchers were led by Charles Cadieux, a Ph.D. student at the Université de Montréal and member of the Institute for Research on Exoplanets (iREx).

With a size and mass slightly greater than that of Earth, the exoplanet is located at a distance from its star where its temperature would be neither too hot nor too cold for liquid water to exist on its surface. The astronomers believe it could be an “ocean planet,” a planet completely covered by a thick layer of water. This would make it similar to some of the moons of Jupiter and Saturn.

Cadieux and his team describe the observations that elucidated the nature and characteristics of this unique exoplanet in an article published on August 12 in The Astronomical Journal.

Artistic representation of the surface of TOI-1452 b, which could be an “ocean planet”, i.e. a planet entirely covered by a thick layer of liquid water. Credit: Benoit Gougeon, Université de Montréal

“I’m extremely proud of this discovery because it shows the high calibre of our researchers and instrumentation,” said René Doyon, Université de Montréal Professor and Director of iREx and of the Observatoire du Mont-Mégantic (OMM). “It is thanks to the OMM, a special instrument designed in our labs called SPIRou, and an innovative analytic method developed by our research team that we were able to detect this one-of-a-kind exoplanet.”

It was NASA’s space telescope TESS, which surveys the entire sky in search of planetary systems close to our own, that put the astronomers on the trail of this exoplanet. Based on the TESS signal, which showed a slight decrease in brightness every 11 days, scientists predicted a planet about 70% larger than Earth.

Charles Cadieux belongs to a group of astronomers that does ground follow-up observations of candidates identified by TESS in order to confirm their planet type and characteristics. He uses PESTO, a camera installed on the OMM’s telescope that was developed by Université de Montréal Professor David Lafrenière and his Ph.D. student François-René Lachapelle.

국제 천문학 팀이 물로 완전히 덮일 수 있는 외계행성을 발견했습니다. 크레딧: Benoit Gougeon, 몬트리올 대학교

Cadeaux는 “OMM은 이 신호의 특성을 확인하고 행성의 반경을 추정하는 데 중요한 역할을 했습니다.”라고 설명했습니다. “이것은 일상적인 검사가 아니었습니다. 우리는 TESS가 감지한 신호가 실제로 그 쌍성계에서 가장 큰 두 별인 TOI-1452를 도는 외계행성에 의해 발생한 것인지 확인해야 했습니다.”

호스트 별 TOI-1452는 우리 태양보다 훨씬 작으며 쌍성계에서 비슷한 크기의 두 별 중 하나입니다. 두 별은 서로 공전하며 97개의 천문 단위 또는 태양과 태양 사이 거리의 약 2.5배인 작은 거리만큼 떨어져 있습니다.[{” attribute=””>Pluto — that the TESS telescope sees them as a single point of light. But PESTO’s resolution is high enough to distinguish the two objects, and the images showed that the exoplanet does orbit TOI-1452, which was confirmed through subsequent observations by a Japanese team.

Ingenuity at work

To determine the planet’s mass, the astronomers then observed the system with SPIRou, an instrument installed on the Canada-France-Hawaii Telescope in Hawai’i. Designed in large part in Canada, SPIRou is ideal for studying low-mass stars such as TOI-1452 because it operates in the infrared spectrum, where these stars are brightest. Even then, it took more than 50 hours of observation to estimate the planet’s mass, which is believed to be nearly five times that of Earth.

Étienne Artigau and Neil Cook, researchers also with iREx at the Université de Montréal, played a key role in analyzing the data. They developed a powerful analytic method capable of detecting the planet in the data collected with SPIRou. “The LBL method [for line-by-line] 이를 통해 기생충의 많은 신호에서 SPIRou로 얻은 데이터를 정리하고 우리 팀이 발견한 행성과 같은 약한 서명을 밝힐 수 있습니다.”라고 Artigau가 설명했습니다.

팀에는 박사 학위를 보유한 퀘벡 연구원 Farbod Jahandar와 Thomas Vandal도 포함됩니다. 몬트리올 대학교 학생들. Jahandar는 행성의 내부 구조를 제한하는 데 유용한 호스트 별의 구성을 분석했으며 Vandal은 SPIRou로 수집된 데이터 분석에 참여했습니다.

물의 세계

외계행성 TOI-1452 b는 지구만큼 암석이 많지만 반지름, 질량 및 밀도는 우리와 매우 다른 세계를 암시합니다. 지구는 기본적으로 매우 건조한 행성입니다. 표면의 약 70%가 바다로 덮여 있기 때문에 때때로 푸른 행성이라고 부르지만, 실제로 물은 질량의 아주 작은 비율(1% 미만)을 차지합니다.

일부 외계행성에서는 물이 더 풍부할 수 있습니다. 최근 몇 년 동안 천문학자들은 크기가 지구에서[{” attribute=””>Neptune (about 3.8 times larger than Earth). Some of these planets have a density that can only be explained if a large fraction of their mass is made up of lighter materials than those that make up the internal structure of the Earth such as water. These hypothetical worlds have been dubbed “ocean planets.”

“TOI-1452 b is one of the best candidates for an ocean planet that we have found to date,” said Cadieux. “Its radius and mass suggest a much lower density than what one would expect for a planet that is basically made up of metal and rock, like Earth.”

The University of Toronto’s Mykhaylo Plotnykov and Diana Valencia are specialists in exoplanet interior modeling. Their analysis of TOI-1452 b shows that water may make up as much as 30% of its mass, a proportion similar to that of some natural satellites in our Solar System, such as Jupiter’s moons Ganymede and Callisto, and Saturn’s moons Titan and Enceladus.

To be continued…

An exoplanet such as TOI-1452 b is a perfect candidate for further observation with the James Webb Space Telescope, or Webb for short. It is one of the few known temperate planets that exhibit characteristics consistent with an ocean planet. It is close enough to Earth that scientists can hope to study its atmosphere and test this hypothesis. And, in a stroke of good fortune, it is located in a region of the sky that the telescope can observe year-round.

“Our observations with the Webb Telescope will be essential to better understanding TOI-1452 b,” said Doyon who overviewed the conception of James Webb’s component Near Infrared Imager and Slitless Spectrograph (NIRISS). “As soon as we can, we will book time on Webb to observe this strange and wonderful world.”

Reference: “TOI-1452 b: SPIRou and TESS reveal a super-Earth in a temperate orbit transiting an M4 dwarf” by Charles Cadieuxg, René Doyon, Mykhaylo Plotnykov, Guillaume Hébrard, Farbod Jahandar, Étienne Artigau, Diana Valencia, Neil J. Cook, Eder Martioli, Thomas Vandal, Jean-François Donati, Ryan Cloutier, Norio Narita, Akihiko Fukui, Teruyuki Hirano, François Bouchy, Nicolas B. Cowan, Erica J. Gonzales, David R. Ciardi, Keivan G. Stassun, Luc Arnold, Björn Benneke, Isabelle Boisse, Xavier Bonfils, Andrés Carmona, Pía Cortés-Zuleta, Xavier Delfosse, Thierry Forveille, Pascal Fouqué, João Gomes da Silva, Jon M. Jenkins, Flavien Kiefer, Ágnes Kóspál, David Lafrenière, Jorge H. C. Martins, Claire Moutou, J.-D. do Nascimento Jr., Merwan Ould-Elhkim, Stefan Pelletier, Joseph D. Twicken, Luke G. Bouma, Scott Cartwright, Antoine Darveau-Bernier, Konstantin Grankin, Masahiro Ikoma, Taiki Kagetani, Kiyoe Kawauchi, Takanori Kodama, Takayuki Kotani, David W. Latham, Kristen Menou, George Ricker, Sara Seager, Motohide Tamura, Roland Vanderspek and Noriharu Watanabe, 12 August 2022, The Astronomical Journal.
DOI: 10.3847/1538-3881/ac7cea

The article was published on August 12, 2022, in The Astronomical Journal. In addition to Charles Cadieux, René Doyon, Étienne Artigau, Neil Cook, Farbod Jahandar and Thomas Vandal at the Université de Montréal’s iREx, the research team includes Nicolas B. Cowan (iREx, MSI, McGill, Canada); Björn Benneke, Stefan Pelletier and Antoine Darveau-Bernier (iREx, UdeM, Canada); Ryan Cloutier, former member of iREx (Harvard, U.S.); and co-authors from University of Toronto, France, Brazil, the United States, Japan, Spain, Switzerland, Portugal, Hungary, Germany, and Crimea.