A Record-Breaking Star and Its Exoplanet

A small star and its orbiting planet are flying through the Milky Way at an incredible pace, according to a NASA team’s analysis of the object.

The Speed of Light

The system is believed to be traveling at least 1.2 million miles per hour (1.93 million kilometers per hour), making the exoplanet the first found orbiting such a fast-moving star. This is the fastest speed ever recorded for a star and its planet, according to a NASA release. The team’s analysis was published in The Astronomical Journal.

A Mystery from 2011

The objects were first spotted in 2011 after astronomers reviewed archival data from the Microlensing Observations in Astrophysics (MOA) project. The team believed the objects were either a star larger than our Sun and a planet about 29 times heavier than Earth, or a planet about four times the size of Jupiter with a moon smaller than our planet. Either way, the larger object is about 2,300 times heavier than its partner.

Determining the Speed

The team calculated the system’s transverse velocity, or the amount it moved across the sky, to determine its speed. Data from the Keck Observatory and ESA’s Gaia satellite indicate that the object is a star, but the team plans to revisit the object in a year to confirm its identity.

A Rogue Planet?

"If high-resolution observations show that the star just stays in the same position, then we can tell for sure that it is not part of the system that caused the signal," said study co-author Aparna Bhattacharya, a research scientist at NASA Goddard and the University of Maryland, College Park, in the same release. "That would mean the rogue planet and exomoon model is favored."

A Hypervelocity Star System?

Based on the system’s superlative speed, it may be a hypervelocity star system. Such a system may have reached its extreme speed through interactions with the gravitational fields of other stars or objects like black holes, which have extremely strong gravitational fields.

Artist’s Concept

An artist’s concept of stars moving through the Milky Way center, with colored trails indicating their speed (the redder the trail, the faster the star). Illustration: NASA/JPL-Caltech/R. Hurt (Caltech-IPAC)

Exoplanets: Worlds Beyond Our Solar System

Exoplanets are worlds that exist beyond our solar system. They come in many shapes and sizes, including super-Earths, super-Neptunes, and hot Jupiters. Recent discoveries, such as the Webb telescope’s reveal of a familiar exoplanet’s atmosphere and the identification of a massive exoplanet, demonstrate the ongoing exploration of these mysterious worlds.

Upcoming Discoveries

The Roman Space Telescope, set to launch by May 2027, should reveal more of these enigmatic worlds, as well as a wealth of new discoveries across the cosmos.

Future Observations

"Roman will do it all," said Terry in the same release. "In this case, we used MOA for its broad field of view and then followed up with Keck and Gaia for their sharper resolution, but thanks to Roman’s powerful view and planned survey strategy, we won’t need to rely on additional telescopes."

Until then, we can revel in the incredible speed of this star and its planet, and wait for their identity to be confirmed, perhaps as soon as next year.