How does this planet stay attached to a star racing at 1.2 million mph? 💫

A star racing at high speed through our galaxy is dragging along a massive planet. This discovery surprises scientists, who expected the planet to be ejected during such a cosmic journey.

The initial observation dates back to 2011, when a fleeting light distortion revealed the presence of this unusual duo. A low-mass star and its companion, a super-Neptune-sized planet, are moving at a dizzying speed, astonishing astronomers.


Hypervelocity stars are rare objects, often ejected from their original galaxy by intense gravitational interactions. This particular system, however, is the first where a planet has been detected orbiting such a star. This discovery challenges current models of planet formation and survival in extreme environments.

Data collected by the Microlensing Observations in Astrophysics survey helped identify this system. Analysis of the light curve revealed the presence of two celestial bodies, one being about 2,300 times more massive than the other. Follow-up observations with the Keck Observatory and the Gaia satellite confirmed the star's impressive distance and speed.

With an estimated speed of 540 kilometers per second (about 1.2 million mph), this star may one day leave the Milky Way. Scientists continue to monitor this system to better understand its origin and fate. This study, published in The Astronomical Journal, opens new perspectives on planetary dynamics in extreme conditions.

Researchers hope future observations will confirm the star's exact speed and determine whether it is sufficient to escape our galaxy's gravitational pull. This discovery highlights the importance of astronomical surveys in understanding the Universe.

How can a planet survive a hypervelocity star?

The discovery of a planet orbiting a hypervelocity star raises questions about planetary survival mechanisms. Current models suggest that extreme gravitational forces should eject planets from their orbits.

Scientists speculate that the planet may have formed after the star's ejection or that the system was ejected as a cohesive entity. The latter hypothesis would imply very specific conditions.

Another possibility is that the planet has a wide enough orbit to resist gravitational disturbances. This would require adjustments in our understanding of planetary system stability.

This discovery encourages astronomers to revisit their theories on planet formation and evolution in extreme dynamic environments.

What is microlensing and how does it help discover exoplanets?

Microlensing is an observation technique that detects objects, such as planets, by analyzing the distortion of light from a distant star. This phenomenon occurs when an object passes between the observer and the star.

This method is particularly useful for discovering planets located at great distances, including those orbiting hypervelocity stars. It does not depend on the host star's brightness, making it effective for studying faint systems.

Microlensing has enabled the discovery of many exoplanets, including those in extreme environments. It complements other detection methods, such as radial velocity measurements or transits.