{"id":563498,"date":"2026-07-01T14:11:16","date_gmt":"2026-07-01T14:11:16","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/563498\/"},"modified":"2026-07-01T14:11:16","modified_gmt":"2026-07-01T14:11:16","slug":"nasas-tess-mission-finds-planetary-system-in-a-new-way","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/563498\/","title":{"rendered":"NASA\u2019s TESS Mission finds planetary system in a new way"},"content":{"rendered":"

For the first time, NASA\u2019s TESS (Transiting Exoplanet Survey Satellite) mission has identified a planet orbiting a distant star thanks to its warping of space-time. Unlike the star-hugging transiting planets TESS regularly reveals, the newfound microlensing world is a super-Jupiter orbiting far from its host star.<\/p>\n

\u201cWhen TESS launched, no one expected it to ever be capable of finding this kind of planet,\u201d said University of New Mexico Professor Diana Dragomir. \u201cThe discovery implies that there are probably other microlensing planets hiding in TESS\u2019s data that we hadn\u2019t previously thought to look for.\u201d<\/p>\n

Astronomers first became aware of the alerting microlensing event, called Gaia23bra b in 2023, using ESA’s (European Space Agency) now-retired Gaia space telescope. Gaia23bra b is fundamentally different from the transiting planets normally found by TESS. Instead of causing a dimming, the star\u2013planet system magnified the light of a more distant background star (the “source”). This occurred when the mass of the foreground star (the “lens”) and its planet bent the background star\u2019s light as the two systems briefly aligned on the sky, an effect known as gravitational microlensing. The time\u2011dependent shape of this brightening is what revealed the presence of a planet and allowed researchers to measure the mass ratio between the planet and its host star.<\/p>\n

Researchers later looked back through archived TESS data and found TESS had caught it too.<\/p>\n

<\/p>\n

\u201cGaia\u2019s observations were too sparse to pick up on the planet. TESS 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.\u201d<\/strong><\/p>\n


\n <\/p>\n

\u2013\u00a0Mallory Harris, UNM\u00a0Ph.D. candidate\u00a0<\/strong><\/p>\n

\n<\/p><\/blockquote>\n

The team\u2019s analysis, which was published July 1 in the Astrophysical Journal Letters<\/a>, revealed that Gaia23bra b is about 1.63 times as massive as Jupiter. It orbits an orange dwarf star that\u2019s about 80 percent of the Sun\u2019s mass at a similar orbital distance Jupiter\u2019s orbit around the Sun. Such a world would be impossible to detect using the primary transit method TESS was designed to employ.<\/p>\n

The discovery also suggests that additional microlensing planets may be hidden within the past eight years of archived TESS observations. Although Gaia23bra b is the first confirmed planet\/star system found using TESS data, researchers believe the mission may have captured other similar events that have yet to be recognized.<\/p>\n

\"microlensing\"<\/p>\n

This animation illustrates the concept of gravitational microlensing. When one star in the sky appears to pass nearly in front of another, the light rays of the background source star become bent due to the warped space-time around the foreground star. This star acts like a virtual magnifying glass, amplifying the brightness of the background source star. If the nearer star harbors a planetary system, then those planets can also act as lenses, each one producing a short deviation in the brightness of the source. When astronomers find planets this way, they can measure their mass and orbital distance from their host star. Credit: NASA\u2019s Goddard Space Flight Center\/CI Lab<\/p>\n


\nMicrolensing 101<\/strong><\/p>\n

Out of more than 6,000 known exoplanets, about three-fourths were discovered via the transit method, TESS\u2019s typical planet-searching technique. Astronomers monitor hordes of stars, watching for ones that periodically dim because orbiting planets cross in front of them \u2014 an event called a transit. Large planets block out the most starlight regardless of their proximity to the host star. The reason the technique is particularly sensitive to close-in planets is that they have the highest probability of transit.<\/p>\n

Microlensing, however, is most sensitive to planets orbiting at Earth-like distances or farther from their stars, making it an important tool for studying planetary systems more like our own solar system. 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\u2019s mass. 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\u2019s light, acting as their own tiny lenses. Astronomers often observe this effect as a spike in the star\u2019s brightness.

\n\u00a0<\/p>\n

<\/p>\n

\u201cThe main advantage of microlensing lies in the kinds of planets it is sensitive to. Planets that orbit very close to their host stars effectively blend with the star\u2019s mass and do not produce a distinct microlensing signal. With microlensing, we can find smaller planets with greater orbital distances, including worlds in the habitable zone of their star and even farther away.\u201d<\/strong><\/p>\n


\n <\/p>\n

\u2013 Mallory Harris, UNM Ph.D. candidate\u00a0<\/strong><\/p>\n

\n<\/p><\/blockquote>\n

\u201cTransits and microlensing are very complementary because they each reveal a category of planet the other may not be able to detect,\u201d Dragomir said. \u201cAnd 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\u2019d otherwise never see.\u201d<\/p>\n

\"TESS<\/p>\n

This graphic highlights the search areas of three planet-hunting missions: NASA\u2019s upcoming Nancy Grace Roman Space Telescope, the retired Kepler Space Telescope, and NASA\u2019s TESS (Transiting Exoplanet Survey Satellite). While TESS discovers transiting planets within a 150-light-year radius of Earth, it recently detected a planet about 40,000 light-years away (marked by the star symbol) via another method, called microlensing. Credit: NASA\u2019s Goddard Space Flight Center<\/p>\n


\nBut microlensing observations are limited-time opportunities.<\/p>\n

\u201cMicrolensing events happen once and they\u2019re gone \u2014 they don\u2019t repeat,\u201d Harris said. \u201cI like to joke that we\u2019ll probably find the first Earth analog with microlensing, and then wave at it as it goes by because we\u2019ll never see it again.\u201d<\/p>\n

That makes detailed observations of microlensing planets difficult. However, as the sample of microlensing planets grows, it becomes possible to study how common wide\u2011orbit, planets are throughout the galaxy and how planetary systems form and evolve over time. This information helps fill an important gap left by transit and radial\u2011velocity surveys, which are strongly biased toward planets orbiting very close to their host stars.<\/p>\n

\u201cTESS has been observing the sky for nearly eight years and has repeatedly monitored regions along the Galactic Plane, where this system is located,\u201d said Harris. \u201cDespite this extensive coverage, Gaia23bra b represents the first definitive microlensing planet discovered using TESS data.\u201d<\/p>\n

The discovery also highlights the power of combining different kinds of space-based observations. Gaia supplied long-term monitoring that identified the event, while TESS observed the field every 200 seconds for nearly 60 days. Those rapid observations allowed researchers to detect subtle features in the microlensing light curve that are often missed by traditional surveys.<\/p>\n

\u201cGaia23bra b is also one of only a very small number of microlensing planets discovered using space\u2011based data, making it an important case study for the upcoming Nancy Grace Roman Space Telescope,\u201d said Harris. \u201cMicrolensing is currently the only method capable of detecting Earth\u2011mass planets at Earth\u2011like orbital distances, so demonstrating that these techniques work in real datasets is particularly valuable for future searches for potentially habitable worlds.<\/p>\n

On track for launch in fall 2026, Roman will observe the center of the galaxy for one of its core surveys, revealing an estimated 1,000 microlensing planets and around 100,000 transiting planets. Because Roman will observe with a similarly continuous cadence, Gaia23bra b serves as an important case study demonstrating what high-cadence, space-based microlensing observations can reveal.<\/p>\n

TESS looks at nearly the whole sky, and is only now beginning to look towards the center of the galaxy which was previously a difficult target due to stray light from the Earth and the Moon contamination. The high density of stars towards the Galactic Bulge increases Roman\u2019s odds of seeing microlensing events, but the stars would blend together in TESS\u2019s large pixels.<\/p>\n

\u201cSince 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,\u201d Dragomir said. \u201cThat means it could help us study planets in regions with different conditions.\u201d<\/p>\n

That could have implications for the search for habitable worlds. Microlensing is currently the only planet-detection technique capable of routinely finding Earth-mass planets at Earth-like orbital distances, making it a critical tool for future studies of potentially habitable planetary systems. Most microlensing events are typically observed once per night or less frequently, especially outside the Galactic Bulge.<\/p>\n

To learn more, visit the TESS mission<\/a>.\u00a0<\/p>\n

Top image:\u00a0

\nThis artist\u2019s concept visualizes Gaia23bra b, the first microlensing planet orbiting a distant star found by NASA\u2019s TESS (Transiting Exoplanet Survey Satellite). This super-Jupiter orbits an orange dwarf star at a distance similar to Jupiter\u2019s distance from the Sun. Credit: NASA\u2019s Goddard Space Flight Center<\/strong><\/p>\n

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