For the first time, NASA’s TESS (Transiting Exoplanet Survey Satellite) mission has identified a planet orbiting a distant star thanks to ripples in space-time. Unlike the star-hugging transiting planets TESS regularly reveals, the newfound world is a super-Jupiter orbiting far from its host star.
美国宇航局的 TESS（凌日系外行星勘测卫星）任务首次利用时空涟漪识别出一颗围绕遥远恒星运行的行星。与 TESS 经常揭示的环绕恒星的凌日行星不同，新发现的世界是一颗远离其主恒星运行的超级木星。
“When TESS launched, no one expected it to ever be capable of finding this kind of planet,” said Diana Dragomir, a professor at the University of New Mexico in Albuquerque and co-author of a paper describing the results. At 1.6 times Jupiter’s mass and a similar orbital distance, it would be extremely unlikely to find such a planet via the primary detection method TESS was designed for. “The discovery implies that there are probably other so-called microlensing planets hiding in TESS’s data that we hadn’t previously thought to look for.”
“当 TESS 发射时，没有人想到它能够找到这种行星，”阿尔伯克基新墨西哥大学教授、描述结果的论文合著者戴安娜·德拉戈米尔 (Diana Dragomir) 说。由于质量是木星的 1.6 倍且轨道距离相似，通过 TESS 设计的主要探测方法找到这样一颗行星的可能性极小。 “这一发现意味着 TESS 的数据中可能还隐藏着其他我们之前没有想过要寻找的所谓的微透镜行星。”
Astronomers found the first hint of the planet, called Gaia23bra b, in 2023 using ESA’s (European Space Agency) now-retired Gaia space telescope. Gaia’s alert system flagged a star that brightened — something that can happen when a foreground star passes in front of a more distant one and magnifies its light through gravitational microlensing.
天文学家于 2023 年使用欧洲航天局 (ESA) 现已退役的盖亚太空望远镜发现了这颗行星的第一个线索，称为 Gaia23bra b。盖亚的警报系统标记了一颗变亮的恒星——当前景恒星经过一颗更远的恒星前面并通过引力微透镜放大其光线时，就会发生这种情况。
Researchers later looked back through archived TESS data and found TESS had caught it too.
研究人员后来回顾了 TESS 的存档数据，发现 TESS 也发现了它。
“Gaia’s observations were too sparse to pick up on the planet,” said Mallory Harris, a Ph.D. candidate at the University of New Mexico, who led the study. “The TESS spacecraft happened to be monitoring the same area of the sky during the event, and its denser time coverage showed extra features in the light curve caused by a planet.”
“盖亚的观测结果太稀疏，无法在地球上进行观测，”博士马洛里·哈里斯说。领导这项研究的新墨西哥大学候选人。 “TESS 航天器恰好在事件期间监测天空的同一区域，其更密集的时间覆盖显示了行星引起的光变曲线的额外特征。”
The team’s analysis, published July 1 in The Astrophysical Journal Letters , revealed that Gaia23bra b, which orbits an orange dwarf star that’s about 80 percent of the Sun’s mass, is nearly 40,000 light-years away from Earth, far exceeding TESS’s usual search radius of about 150 light-years.
该团队的分析于 7 月 1 日发表在《天体物理学杂志快报》上，显示 Gaia23bra b 围绕着一颗质量约为太阳 80% 的橙矮星运行，距离地球近 40,000 光年，远远超过 TESS 通常约 150 光年的搜索半径。
Out of more than 6,000 known exoplanets (worlds outside our solar system), about three-fourths were discovered via the transit method, TESS’s typical planet-hunting technique. Astronomers monitor hordes of stars, watching for ones that periodically dim as orbiting planets cross in front of them — an event called a transit.
在 6,000 多颗已知的系外行星（太阳系以外的世界）中，大约四分之三是通过凌日法发现的，这是 TESS 典型的行星搜寻技术。天文学家监测成群的恒星，观察那些随着绕轨道运行的行星从它们面前穿过而周期性变暗的恒星——这种事件称为凌日。
Microlensing has revealed less than 5% of known exoplanets. This light-bending phenomenon occurs when two stars align closely from our vantage point. Light from the more distant star curves as it travels through the warped space-time caused by the nearer star’s mass.
微透镜揭示了不到 5% 的已知系外行星。当两颗恒星从我们的有利位置紧密排列时，就会发生这种光弯曲现象。来自较远恒星的光在穿过较近恒星质量造成的扭曲时空时会发生弯曲。
If the alignment is especially close, the nearer star acts like a cosmic lens, focusing and magnifying light from the background star. Planets orbiting the foreground star may also modify the distant star’s light, acting as their own tiny lenses. Astronomers see the effect as a spike in the star’s brightness.
如果排列特别接近，较近的恒星就像宇宙透镜一样，聚焦并放大来自背景恒星的光。围绕前景恒星运行的行星也可能会改变远处恒星的光线，充当它们自己的微小透镜。天文学家将这种效应视为恒星亮度的峰值。
The transit method is best at finding large planets orbiting very close to their host stars; large planets block the most starlight, while close-in planets are more likely to pass in front of the host star. These gargantuan, steamy worlds are fascinating to scientists, but astronomers want to find planets like those in our solar system, too. That’s microlensing’s specialty.
凌日法最适合寻找距离其主恒星非常近的大型行星。大行星阻挡了大部分星光，而距离较近的行星更有可能从主恒星前面经过。这些巨大的、潮湿的世界对科学家来说很着迷，但天文学家也希望找到像太阳系中的行星一样的行星。这是微透镜的专长。
Microlensing isn’t well suited to finding huge, close-in planets because their gravitational signals would just blur together.
微透镜不太适合寻找巨大的、近距离的行星，因为它们的引力信号会模糊在一起。
“Transits and microlensing are complementary because they each reveal a category of planet the other may not be able to detect,” Dragomir said. “And they offer different details. Transits give us the size of a planet, and in concert with other methods we can determine its mass and density. Microlensing gives us masses and orbital distances for planets we’d otherwise never see.”
德拉戈米尔说：“凌日和微透镜是互补的，因为它们各自揭示了对方可能无法探测到的一类行星。” “它们提供了不同的细节。凌日给我们提供了行星的大小，并与其他方法相结合，我们可以确定它的质量和密度。微透镜给我们提供了我们永远不会看到的行星的质量和轨道距离。”
But microlensing observations are time-limited opportunities.
但微透镜观测是有时间限制的机会。
That makes detailed observations of microlensing planets tough. However, the method can serve as a powerful demographics tool that offers broad information about planetary populations.
这使得对微透镜行星的详细观测变得困难。然而，该方法可以作为一种强大的人口统计工具，提供有关行星人口的广泛信息。
“This is a bit like a preview of the microlensing NASA’s Nancy Grace Roman Space Telescope will do,” said Michael Fausnaugh, a professor at Texas Tech University in Lubbock and a co-author of the study. On track for launch on August 30, 2026, Roman will observe the center of the Milky Way galaxy for one of its core surveys , revealing an estimated 1,000 microlensing planets and around 100,000 transiting planets .
“这有点像美国宇航局南希·格雷斯·罗马太空望远镜的微透镜预览，”拉伯克德克萨斯理工大学教授、该研究的合著者迈克尔·福斯诺说。罗曼预计将于 2026 年 8 月 30 日发射，将观测银河系中心进行一项核心调查，揭示估计有 1,000 颗微透镜行星和大约 100,000 颗凌日行星。
Roman will specifically target the heart of the galaxy because stars are packed so tightly together there, increasing the odds of seeing microlensing events. While that crowding would make many stars blend together in TESS’s larger pixels, TESS looks at nearly the whole sky, where stars are more spread out.
罗曼将专门瞄准银河系的中心，因为那里的恒星紧密地聚集在一起，增加了看到微透镜事件的几率。虽然这种拥挤会使许多星星在 TESS 的较大像素中混合在一起，但 TESS 几乎观察到整个天空，那里的星星更加分散。
“Since TESS looks elsewhere in the galactic plane, it can naturally find microlensing planets in other parts of the galaxy, as demonstrated by this first microlensing planetary system,” Dragomir said. “That means it could help us study planets in regions with different conditions.”
“由于 TESS 在银河系平面的其他地方寻找，它自然可以在银河系的其他部分找到微透镜行星，正如第一个微透镜行星系统所证明的那样，”德拉戈米尔说。 “这意味着它可以帮助我们研究不同条件地区的行星。”
That could have implications for the search for habitable worlds. The bustling galaxy center is rife with radiation from more frequent supernova explosions, which could sterilize planets. And gravitational encounters between crowded stars may disrupt planetary systems. Observations from TESS focus on a milder part of the galaxy.
这可能会对寻找宜居世界产生影响。熙熙攘攘的星系中心充满了更频繁的超新星爆炸的辐射，这可能会使行星灭绝。拥挤的恒星之间的引力相遇可能会扰乱行星系统。 TESS 的观测集中在银河系较温和的部分。
“The key to Roman’s microlensing survey is its dense time coverage targeting the galactic bulge,” Fausnaugh said. “The TESS mission uniquely provides these rapid observations for stars in other parts of the galaxy, and pairing the two opens up prospects for understanding planet formation in a diverse population of stars. Since microlensing finds solar system-like planets, this offers a new chance to understand how planetary systems like our own vary in different regions of the galaxy.”
“罗曼微透镜巡天的关键在于其针对银河核球的密集时间覆盖，”福斯诺说。 “TESS 任务独特地为银河系其他部分的恒星提供了这些快速观测，并将两者结合起来，为了解不同恒星群体中的行星形成开辟了前景。由于微透镜发现了类似太阳系的行星，这为了解像我们这样的行星系统在银河系不同区域中的变化提供了一个新的机会。”
To learn more about the TESS mission, visit:
要了解有关 TESS 任务的更多信息，请访问：
Claire Andreoli NASA’s Goddard Space Flight Center , Greenbelt, Md. 301-286-1940
克莱尔·安德烈奥利 NASA 戈达德太空飞行中心，马里兰州格林贝尔特 301-286-1940