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Astronomers Find Planet in Unusual Polar Orbit Around Twin Suns

Astronomers have discovered an exoplanet, 2M1510 (AB) b, orbiting at a 90° angle around a pair of brown dwarfs—an arrangement never before confirmed in any binary system, opening new questions about how planets form and survive in extreme gravitational environments.

Summary

Astronomers using the European Southern Observatory’s Very Large Telescope detected unexpected wobbling in the brown dwarf pair 2M1510, indicating a third body in the system.
The newly confirmed planet, 2M1510 (AB) b, travels on a polar orbit, meaning its orbital plane is perpendicular to that of its two host brown dwarfs.
The host objects are brown dwarfs—“failed stars” roughly 35 times the mass of Jupiter—that eclipse one another as viewed from Earth, making this only the second known eclipsing brown dwarf binary.
2M1510 (AB) b lies about 120 light-years from Earth, and is likely a gas giant several times Earth’s mass, though exact mass remains uncertain.
This is the first confirmed instance of a circumbinary polar planet, expanding the diversity of known planetary architectures and challenging models of planet formation.
The discovery was serendipitous: observations aimed at characterizing the brown dwarfs revealed orbital perturbations best explained by a third body on a polar trajectory.
The finding appears in Science Advances, led by Thomas Baycroft and Amaury Triaud at the University of Birmingham.
Simulations suggest such polar orbits can remain stable for billions of years, despite the complex gravitational pulls from two central objects.
The discovery hints that other polar circumbinary planets may lurk undetected in existing data sets.
Future observations, including with the James Webb Space Telescope, could probe the planet’s atmosphere and refine its mass and composition.

Astronomers Find Planet in Unusual Polar Orbit Around Twin Suns — Astronomers saw a planet going around two unusual stars. The planet’s path is sideways, not aligned with the stars, at a right angle.

Introduction

Planetary systems around two suns capture the imagination, from science fiction’s Tatooine to real circumbinary worlds discovered by Kepler. Yet all previously confirmed circumbinary planets have orbits roughly aligned with their stars’ orbital plane. The recent detection of 2M1510 (AB) b on a perpendicular path shatters that pattern and reveals new complexity in how planets can orbit multiple hosts.

The Host Brown Dwarfs

Brown dwarfs bridge the gap between stars and giant planets. They pack up to a few tens of Jupiter masses but lack the heft to sustain hydrogen fusion in their cores. The 2M1510 system consists of two such objects, each about thirty-five times Jupiter’s mass, that eclipse each other every few days. From Earth, their mutual eclipses make them stand out as an “eclipsing binary,” an uncommon configuration among brown dwarfs.

Property	2M1510 A	2M1510 B
Mass (Jupiter masses)	~35	~35
Type	Brown dwarf	Brown dwarf
Orbital period	~— days	~— days
Discovery method	SPECULOOS survey	SPECULOOS survey

The Unusual Planet

The planet 2M1510 (AB) b was not found by the usual transit dips but by tiny, rhythmic wobbles in the brown dwarfs’ motion. These perturbations could only be explained by a third body tugging at the binary, and the best fit places that body in a polar, or perpendicular, orbit relative to the brown dwarfs’ plane. This marks the first time a circumbinary planet has been seen on such an orbit.

Characteristic	Value
Orbit inclination	~90° (polar)
Estimated mass	4–5 Earth masses (min.)
Distance from Earth	~120 light-years
Host type	Eclipsing brown dwarf pair
Discovery instrument	ESO VLT

How It Was Discovered

Astronomers led by Thomas Baycroft at the University of Birmingham were analyzing high-precision data from ESO’s Very Large Telescope in Chile when they noticed odd shifts in the timing of the brown dwarfs’ eclipses. After ruling out stellar activity or additional faint stars, the team found that only a planet on a polar orbit could reproduce the observed signals. As Baycroft noted, “I am particularly excited to be involved in detecting credible evidence that this configuration exists”.

Why Polar Orbits Matter

Planets form in discs of gas and dust that usually align with their star’s equator. A polar circumbinary planet suggests dramatic early dynamics—perhaps interactions with other planets or disc warping by the binary—that flipped the orbit by 90°. Such extreme tilts can test and refine models of planet formation under complex gravity.

Implications for Planet Formation Theories

Traditional models struggle to explain how a planet remains stable on a perpendicular path around two massive objects. Computer simulations now must account for strong, time-varying gravitational forces that can pump up orbital eccentricities or eject bodies entirely. The longevity of 2M1510 (AB) b’s orbit implies that polar circumbinary niches can be safe harbors for planets over billions of years.

Future Observations

Follow-up studies will aim to measure the planet’s mass more precisely and search for an atmosphere. Instruments like the James Webb Space Telescope could detect atmospheric signatures, while long-term monitoring will reveal whether the orbit drifts or remains locked in its polar orientation. Surveys may also re-examine other eclipsing binaries for similar wobbles, potentially uncovering more polar worlds.

Facts

Humans once imagined Tatooine worlds in fiction. Now we know nature can produce even stranger setups than movies.
Brown dwarfs glow faintly in infrared, so the sky from 2M1510 (AB) b would show two dim red suns instead of bright yellow ones.
Polar orbits around a binary mean seasons could be extreme: months of darkness followed by months of light as the planet passes above and below the binary plane.

Conclusion

The discovery of 2M1510 (AB) b on a perpendicular orbit shatters our expectations of planetary layouts. It highlights the surprising outcomes possible when planets form in turbulent, multi-body systems. As telescopes grow more powerful, we may find that polar circumbinary planets are not one-off oddities but a hidden population awaiting detection.

References

“Big surprise”: astronomers find planet in perpendicular orbit around pair of stars. ESO. April 16, 2025. ESO — The European Southern Observatory
Luke Skywalker’s planet orbited two stars… brown dwarfs instead? Reuters. April 18, 2025. Reuters
Evidence for a polar circumbinary exoplanet orbiting a pair … Science Advances. Last week. Science
Astronomers detect exoplanet on rare perpendicular path around … SpaceDaily. April 22, 2025. SpaceDaily
Polar planet 2M1510 (AB) b around binary brown dwarfs. Sky at Night Magazine. April 20, 2025. Sky at Night Magazine
A tilted “Tatooine planet” whose two suns aren’t stars at all. Science. Last week. Science
Rare exoplanet orbits twin stars in ‘Star Wars’-like twist. Phys.org. Last week. Phys.org
New Planet In Strange Perpendicular Orbit Around Binary Stars Is … IFLScience. IFLScience
Planet Found Orbiting Two Stars at a Perfect 90-Degree Angle. SciTechDaily. SciTech Daily
Descubren un “planeta Tatooine” en órbita perpendicular… Cadena SER. cadenaser.com

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How Accurate Is Our Current Map of the Solar Neighborhood?

Key Takeaway

While significant advancements have been made in cataloging the stellar population within our solar neighborhood, it remains incomplete. Despite efforts from various astronomical surveys and missions, many dim and small stars, especially brown dwarfs and late M-dwarfs, are still undetected. This highlights the complexity and challenges involved in creating an accurate and comprehensive map of our stellar neighborhood.

Summary

Our Solar Neighborhood is defined as a 20 parsec (65 light-years) sphere centered on the Sun.
Challenges: Many stars are small and dim, making them difficult to detect.
Technological Advances: Infrared sky surveys and missions like Gaia have significantly improved our understanding.
Current Status: The catalog is still incomplete; approximately 21.5% of stellar systems and 23.0% of individual stars within 10 parsecs are likely missing.
Stellar Density: Assumptions of constant stellar density are incorrect due to small-scale density fluctuations.
Future Work: More effort is needed to detect dim stars and refine our stellar catalog.

Dim objects like brown dwarfs are more difficult to detect. This is especially true when looking toward the galactic plane. The reason is that most of the Milky Way’s mass is there.Image Credit: ESA/Gaia/DPAC — Dim objects like brown dwarfs are more difficult to detect. This is especially true when looking toward the galactic plane. The reason is that most of the Milky Way’s mass is there.
Image Credit: ESA/Gaia/DPAC

Our Solar Neighborhood: An Introduction

The Sun’s stellar neighborhood can be defined as a sphere with a radius of 20 parsecs (65 light-years) centered on our star. This region, although relatively small in the vast expanse of the universe, contains a multitude of stars, each with its unique characteristics and challenges for detection.

Challenges in Cataloging the Solar Neighborhood

Dim and Small Stars

The primary challenge in cataloging the solar neighborhood is the presence of dim and small stars. Unlike main sequence stars like our Sun, many stars are significantly less luminous, making them hard to detect with traditional optical telescopes.

Brown Dwarfs: These are substellar objects that are not massive enough to sustain hydrogen fusion in their cores. They are often referred to as “failed stars” due to their inability to shine brightly.
Red Dwarfs: These are small and cool stars, often difficult to detect despite being the most common type of star in the Milky Way.

Technological Advances in Astronomy

Over the decades, technological advancements have played a crucial role in improving our understanding of the solar neighborhood.

Infrared Sky Surveys

Infrared sky surveys have been instrumental in detecting dim stars that are otherwise invisible in optical wavelengths.

Two Micron All-Sky Survey (2MASS): This survey provided a new and unprecedented look at the sky, uncovering numerous M dwarfs, brown dwarfs, and substellar objects.
Sloan Digital Sky Survey: This survey strengthened our catalog of the sky, further enhancing our understanding of the stellar population.

An artist’s conception of a brown dwarf. Brown dwarfs are more massive than Jupiter. But they are less massive than the smallest main sequence stars. Their dimness and low mass make them difficult to detect. Image: By NASA/JPL-Caltech (http://planetquest.jpl.nasa.gov/image/114) [Public domain], via Wikimedia Commons.

Current Status of Our Stellar Catalog

Despite these advancements, our catalog of the solar neighborhood remains incomplete. A recent study by Kirkpatrick et al. found 462 objects in 339 systems within 10 parsecs of the Sun, but further research indicated that many stars are still missing.

Missing Stars and Systems

The study by Scholz and Mints estimated significant deficits in our stellar catalog:

star systems: Approximately 21.5% of star systems within 10 parsecs are missing.
Individual Stars: Approximately 23.0% of individual stars within 10 parsecs are missing.

Assumptions and Their Implications

Two critical assumptions have shaped our understanding of the solar neighborhood:

Survey Completeness out to 5 Parsecs: This assumption has been challenged by recent discoveries.
Uniform Stellar Density out to 10 Parsecs: This assumption is also in question due to small-scale density fluctuations.

Density Fluctuations

The presence of small-scale density fluctuations indicates that the assumption of a constant stellar density is incorrect. These fluctuations can partly explain the deficits in our stellar catalog.

Future Work and Challenges

To achieve a more complete and accurate map of our solar neighborhood, astronomers must continue their efforts to detect dim stars and refine their techniques.

Improved Detection Methods: Developing more sensitive instruments and methods to detect dim stars like brown dwarfs and late M-dwarfs.
Continued Surveys: Conducting more comprehensive and detailed surveys to fill in the gaps in our current catalog.

Proxima Centauri. Credit: ESA/Hubble & NASA

Conclusion

While significant progress has been made in cataloging the stellar population within our solar neighborhood, the work is far from complete. The challenges posed by dim and small stars, combined with the limitations of current detection methods, mean that many stars remain undetected. Future efforts must focus on improving detection techniques and conducting more detailed surveys to create a more accurate and comprehensive map of our stellar neighborhood.

Tables

Table 1: Estimated Deficits in Stellar Catalog

Star Type	Estimated Deficit (%)
AFGK Stars	28.1%
White Dwarfs	31.0%
M-Dwarfs	27.8%

Table 2: Key Astronomical Surveys

Survey Name	Key Contributions
Two Micron All-Sky Survey (2MASS)	Detected numerous M dwarfs, brown dwarfs, and substellar objects
Sloan Digital Sky Survey	Strengthened the stellar catalog and enhanced our understanding of the sky

References:

Hashtags

#astronomy, #solarneighborhood, #stellarcatalog, #browndwarfs, #infraredsurveys, #Gaia, #ProximaCentauri, #Mdwafs

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