Astronomers have identified two exceptionally low-density planets, designated as 'super-puffs,' orbiting the star TOI-791.

天文學家已識別出兩顆密度極低、被稱為「超級棉花糖」的行星，正圍繞恆星 TOI-791 運行。

The detection of TOI-791 b and TOI-791 c was facilitated by the Transiting Exoplanet Survey Satellite (TESS), which recorded periodic luminosity decreases of the host star over a seven-year duration. This Sun-like star, situated approximately 1,110 to 1,113 light-years from Earth in the constellation Volans, hosts two planets of Jovian dimensions but negligible mass. Specifically, TOI-791 b possesses 3.0 percent of Jupiter's mass, while TOI-791 c possesses 5.9 percent. The determination of these masses was achieved through the analysis of transit timing variations, resulting from the mutual gravitational perturbations between the two bodies.

TOI-791 b 與 TOI-791 c 的發現得益於凌日系外行星巡天衛星 (TESS)，該衛星記錄了主恆星在七年期間的週期性亮度下降。這顆類太陽恆星位於天池座，距離地球約 1,110 至 1,113 光年，擁有兩顆體積與木星相當但質量極低的行星。具體而言，TOI-791 b 的質量為木星的 3.0%，而 TOI-791 c 則為 5.9%。這些質量的確定是透過分析兩者間相互重力擾動所導致的凌日時間變化而實現的。

These celestial bodies exhibit anomalous orbital periods of 139 and 232 days, respectively. Such extended orbits necessitate prolonged observation windows for confirmation. The rarity of this system is underscored by the fact that fewer than 40 super-puff planets have been confirmed among nearly 6,300 known exoplanets. The presence of two such entities within a single system is particularly infrequent. Theoretical frameworks suggest these planets originate from gas-rich disks around nascent stars, subsequently losing significant material over time.

這些天體表現出分別為 139 天和 232 天的異常軌道週期。如此延長的軌道需要更長的觀測視窗才能予以確認。在近 6,300 顆已知系外行星中，僅有不到 40 顆被確認為超級棉花糖行星，凸顯了該系統的罕見性。單一系統中同時存在兩顆此類天體尤為罕見。理論框架認為，這些行星起源於新生恆星周圍富含氣體的星盤，隨後隨著時間流逝失去了大量物質。

Institutional collaboration involving the University of Oxford, the University of Birmingham, and the Université Côte d’Azur led to the publication of these findings in the Monthly Notices of the Royal Astronomical Society. Future research objectives include the utilization of the James Webb Space Telescope to ascertain the chemical composition of the atmospheres—hypothesized to consist primarily of hydrogen and helium—and to evaluate the influence of planetary spin and stellar tilt on orbital migration.

由牛津大學、伯明翰大學與蔚藍海岸大學參與的機構合作，將這些發現發表於《皇家天文學會月報》。未來的研究目標包括利用詹姆斯·韋伯太空望遠鏡來確定大氣層的化學組成（假設主要由氫和氦組成），並評估行星自轉與恆星傾斜對軌道遷移的影響。

The discovery of these low-density planets provides a new dataset for analyzing the mechanisms of planetary formation and evolution.

發現這些低密度行星，為分析行星形成與演化的機制提供了新的數據集。