NASA originally published this article on August 15, 2024. Edits by EarthSky.
A solitary star rushing throughout our galaxy
Most acquainted stars peacefully orbit the middle of the Milky Way. However citizen scientists engaged on NASA’s Backyard Worlds: Planet 9 venture have helped uncover an object transferring so quick that it’s going to escape the Milky Way’s gravity and shoot into intergalactic space.
This hypervelocity object is the primary such object discovered with the mass of a small star. It’s additionally the closest hypervelocity star to our sun.
The Yard Worlds venture makes use of pictures from NASA’s WISE (Extensive-field Infrared Explorer) mission, which mapped the sky in infrared mild from 2009 to 2011. It was reactivated as NEOWISE (Close to-Earth Object Extensive-field Infrared Survey Explorer) in 2013, and retired on August 8, 2024.
A number of years in the past, longtime Yard Worlds citizen scientists Martin Kabatnik, Thomas P. Bickle, and Dan Caselden noticed a faint, fast-moving object referred to as CWISE J124909.08+362116.0 marching throughout their screens within the WISE pictures. Observe-up observations with a number of ground-based telescopes helped scientists verify the invention and characterize the item. These citizen scientists at the moment are co-authors on the workforce’s examine about this discovery, to be revealed within the Astrophysical Journal Letters (a pre-print version is available here). Kabatnik, a citizen scientist from Nuremberg, Germany, stated:
I can’t describe the extent of pleasure. Once I first noticed how briskly it was transferring, I used to be satisfied it should have been reported already.
Low-mass star or brown dwarf?
CWISE J1249 is zooming out of the Milky Way at about 1 million miles per hour (1.6 million kph). But it surely additionally stands out for its low mass, which makes it tough to categorise as a celestial object. It might be a low-mass star. But when it doesn’t steadily fuse hydrogen in its core, it could be thought-about a brown dwarf, someplace between a gas giant planet and a star.
Peculiar brown dwarfs will not be that uncommon. Yard Worlds: Planet 9 volunteers have found greater than 4,000 of them! However not one of the others are identified to be on their means out of the galaxy.
This new object has one more distinctive property. Knowledge obtained with the W. M. Keck Observatory in Maunakea, Hawaii, present that it has a lot much less iron and different metals than different stars and brown dwarfs. This uncommon composition means that CWISE J1249 is kind of previous, probably from one of many first generations of stars in our galaxy.
Why is the star so quick?
Why does this object transfer at such excessive velocity? One idea is that CWISE J1249 initially got here from a binary system with a white dwarf, which exploded as a supernova when it pulled off an excessive amount of materials from its companion. One other risk is that it got here from a tightly certain cluster of stars referred to as a globular cluster, and an opportunity assembly with a pair of black holes despatched it hovering away.
Kyle Kremer, incoming assistant professor in UC San Diego’s Division of Astronomy and Astrophysics, stated:
When a star encounters a black hole binary, the complicated dynamics of this three-body interplay can toss that star proper out of the globular cluster.
Scientists will look extra intently on the elemental composition of CWISE J1249 for clues about which of those situations is extra probably.
Successful for citizen science
This discovery has been a workforce effort on a number of ranges: a collaboration involving volunteers, professionals, and college students. Kabatnik credit different citizen scientists with serving to him search, together with Melina Thévenot. He stated that Melina:
… blew my thoughts together with her private weblog about doing searches utilizing Astronomical Knowledge Question Language.
Software program written by citizen scientist Frank Kiwy was additionally instrumental on this discovering, Kabatnik stated.
The examine is led by Yard Worlds: Planet 9 science workforce member Adam Burgasser, a professor on the College of California, San Diego, and consists of co-authors Hunter Brooks and Austin Rothermich, astronomy college students who each started their astronomy careers as citizen scientists.
Need to assist uncover the following extraordinary space object? Join Backyard Worlds: Planet 9 here. Participation is open to anybody in any nation worldwide.
Backside line: Citizen scientists have found a solitary star transferring so quick that it’s going to ultimately escape the Milky Way’s gravity and shoot into intergalactic space.
