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An object discovered with the help of citizen scientists is moving so fast through the Milky Way that it can escape the galaxy’s gravity and reach intergalactic space, new research has found.
Likely a faint red star, the object zoomed in at about 1.3 million miles per hour (600 kilometers per second). By comparison, the Sun orbits the Milky Way at 450,000 miles per hour (200 kilometers per second).
If confirmed, the object would be the first known “high-velocity” very low-mass star, according to a team of astronomers and citizen scientists whose study was published Astrophysical Journal Letters.
Roman Gerasimov, a postdoctoral researcher in the university’s Department of Physics and Astronomy, said there are more low-mass stars than high-mass stars because star formation is low-mass and high-mass stars have short lifetimes. Notre Dame. But low-mass stars are harder to detect because they are cooler and less luminous.
Faster stars, first Considered to be in 1988 and discovered in 2005, are already extremely rare, which makes this new discovery “particularly exciting,” he said.
Volunteers participate in the project Backyard Worlds: Planet 9 CWISE first discovered the star, named J124909.08+362116.0, or J1249+36 for short. Researchers involved in the project are looking for undiscovered objects in the “backyard of the solar system” beyond Neptune, or evidence of a large hypothetical world known as Planet Nine.
Backyard Worlds participants look for patterns and anomalies in images and data collected by NASA’s Wide-Field Infrared Survey Explorer mission, which mapped the sky in infrared light from 2009 to 2011. In 2013 the field infrared probe Explorer will be fully retired on August 8 to monitor near-Earth asteroids and comets.)
J1249 + 36 was given to citizen scientists a few years ago because the star is moving at 0.1% the speed of light, according to the study authors.
“I can’t describe the level of excitement,” citizen scientist Martin Kabatnik of Nuremberg, Germany, said in a statement. “When I first saw how fast it was moving, I believed it should have been announced already.”
Follow-up observations with multiple telescopes zeroed in on the object and helped confirm the discovery.
“The source was particularly interesting because its speed and trajectory showed it was moving fast enough to escape the Milky Way,” Adam Burgasser, a professor of astronomy and astrophysics at the University of California San Diego, said in a statement.
The star’s low mass initially made it difficult to classify, and astronomers questioned whether it was a low-mass star or a brown dwarf, a star or planet-less object.
Brown dwarfs are much bigger than planets, but not as big as stars, and citizen scientists working on the Backyard Worlds project have discovered more than 4,000 of them.
But none of those brown dwarfs are speeding down a path that takes them out of the galaxy. “Runaway” Superstars observed by astronomers in the last two decades.
Astronomers observed J1249+36 using ground-based telescopes, including the WM Keck Observatory on Mauna Kea, Hawaii, and the University of Maui’s Pan-STARS telescope on Maui’s Haleakala Volcano.
Data from the Keck Observatory’s near-infrared Echelon spectrograph suggested the star was an L subdwarf, or a star with a much lower mass and cooler temperature than the Sun. Cool subdwarfs are the oldest stars in the galaxy.
Telescope data reflect that the star has a lower concentration of metals such as iron than other stars or brown dwarfs.
By combining data from multiple telescopes, astronomers determined the star’s position and speed in space, allowing them to predict that it will exit the Milky Way at some point.
But there are questions about the substance’s authenticity.
“I calculated the mass of this object to be approximately 8% of the mass of the Sun by comparing its observed properties with computer simulations of stellar evolution,” Gerasimov said. “This places this object at the lower limit of allowed stellar masses, and it is possible that the mass of the object is actually slightly below that limit, indicating that the object is not a star but a brown dwarf.”
According to the study’s authors, finding more details about the object could help astronomers determine whether it represents a broader population of high-velocity, low-mass objects.
Understanding its exact nature will help them determine when it will leave the galaxy. Earlier, astronomers detected a quick kick to a star at the center of the Milky Way, leaving the galaxy in about 100 million years.
Researchers believe there are two possible scenarios to put J1249+36 on its fast track.
The research team said the star could be a companion to a white dwarf star, the remnant core of a dead star that has ejected the gases that served as its nuclear fuel. In these star pairs, if the two stars are close, the white dwarf will have a massive separation of mass from its companion and an explosion known as a nova. And if the white dwarf accumulates too much mass, it will collapse and explode in a supernova.
“In this type of supernova, the white dwarf is completely destroyed, so its companion is released and it flies off at the same orbital speed that it was originally moving, and also gets a little kick from the supernova explosion,” Barkaser said. “Our calculations show that this scenario works. However, the white dwarf no longer exists, and the remnants of an explosion millions of years ago have already dissipated, so we have no definitive evidence that this is its origin.
Another possibility is that J1249+36 was a globular, closely packed group of stars in a globular cluster. Astronomers predict that at the center of such clusters are black holes of different masses. Black holes can form binary pairs that can catapult any stars that come too close.
“When a star encounters a black hole binary, the complex dynamics of these three-body interactions can throw the star out of the globular cluster,” said Kyle Kremer, incoming assistant professor in the Department of Astronomy at the University of California, San Diego. Astrophysics, in a report.
Kremer ran simulations and found that three-body interactions could knock a low-mass subdwarf star out of a cluster and put it on a path like J1249+36.
“This proves the proof of concept, but we don’t know which globular cluster this star comes from,” Kremer said.
Gerasimov is particularly intrigued by the idea that material was ejected from a globular cluster because stars from 13 billion years ago are in such clusters.
“The chemical composition and distribution of stellar masses in globular clusters capture the early steps of our galaxy’s formation and evolution,” he said. “However, most of what we know about globular clusters comes from studies of their more massive members, as low-mass stars and brown dwarfs are more difficult to observe.”
The James Webb Space Telescope recently allowed astronomers to identify the first brown dwarfs in a globular cluster, which have similar masses to matter. But there are few examples so far to narrow down a broader understanding.
“However, the existence of this high-velocity star opens up a new way to study low-mass cluster members by looking for those that have been ejected and are traveling through the solar neighborhood at high speeds, if it is indeed a former member of a globular cluster,” Gerasimov said. Many may be discovered.”
Retracing J1249+36’s path so far could lead to a crowded part of the night sky where undiscovered clusters are waiting to be discovered, the researchers said.
Now, scientists hope to learn more clues from the star’s elemental composition that could help explain how it ended up on a trajectory rising from the Milky Way.
When white dwarfs explode, they create heavier elements that can be around J1249+36. Similarly, stars in globular clusters throughout the Milky Way have unique patterns of elements that act as calling cards for their origins.
“We’re basically looking for a chemical fingerprint that indicates which system this star belongs to,” Gerasimov said.
