Scientists: Brown Dwarf Identified 30 Years Ago Is Two Objects
2024-10-28
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1Astronomers have made a surprising discovery about the first brown dwarf ever identified.
2New observations suggest the object is actually two brown dwarfs orbiting each other.
3The American space agency NASA describes a brown dwarf as an object that "straddles the dividing line between stars and planets."
4Brown dwarfs form like stars. This means they can grow dense and hot enough to collapse under their own gravity.
5But they never grow dense or hot enough to begin the process of nuclear fusion needed to turn into a star, NASA said.
6Because of this, brown dwarfs are sometimes called failed stars.
7Many brown dwarfs are similar to gas giant planets and weigh just a few times more than the mass of Jupiter.
8Others can be much larger.
9The first brown dwarf was discovered in 1995 by researchers from the California Institute of Technology (Caltech).
10The discovery was made with the help of the institute's Palomar Observatory near San Diego, California.
11But after many years of studying the object, known as Gliese 229B, scientists wondered why its brightness was less than expected for an object of its size.
12New research now shows that the brown dwarf is actually two objects.
13The observations came from the Very Large Telescope, which sits in a desert area of northern Chile.
14Those observations showed that one of the brown dwarfs is about 38 times the mass of Jupiter, while the other is 34 times Jupiter's mass.
15In a statement, the researchers said data collected by the telescope suggests the two objects orbit each other every 12 days.
16That is less than half the time it takes for the moon to orbit the Earth.
17"The observed brightness levels of the pair match what is expected for two small dim brown dwarfs in this mass range," the statement added.
18The two brown dwarfs are gravitationally linked to each other in what is known as a binary system.
19Such a situation is commonly observed among stars but is rare for brown dwarfs.
20After the new discovery, the two objects were given new names - Gliese 229Ba and Gliese 229Bb.
21The brown dwarfs are believed to orbit a star called a red dwarf.
22The two sit about 19 light-years away from our solar system.
23A light-year is the distance light travels in one year - about 9.5 trillion kilometers.
24The research was co-led by Jerry Xuan, a graduate student at Caltech.
25He said in a statement that Gliese 229B was always considered "the poster child" for a brown dwarf.
26"And now we know we were wrong all along about the nature of the object," he added.
27"It's not one but two. We just weren't able to probe separations this close until now."
28Astronomers had identified brown dwarf pairs before, but never any that orbited each other so closely.
29The research results recently appeared in a study in the publication Nature.
30The team that discovered Gliese 229B in 1995 included Rebecca Oppenheimer. At the time, she was a Caltech graduate student.
31She is now an astrophysicist at the American Museum of Natural History in New York City.
32She was also a member of the latest research team.
33Oppenheimer said, "It shows you how weird the universe is, and how different solar systems are from our own."
34She added that she sees the new finding as "the most exciting and fascinating discovery" in this area of astrophysics in many years.
35Caltech's Jerry Xuan said the discovery suggests there might be other brown dwarfs closely orbiting each other.
36He added that he hopes the latest finding can lead to a greater understanding of brown dwarf development.
37"We still don't really know how different brown dwarfs form, and what the transition between a giant planet and a brown dwarf is," Xuan said.
38He added, "This goes to show how complex and messy the star formation process is. We should always be open to surprises."
39I'm Bryan Lynn.
1Astronomers have made a surprising discovery about the first brown dwarf ever identified. New observations suggest the object is actually two brown dwarfs orbiting each other. 2The American space agency NASA describes a brown dwarf as an object that "straddles the dividing line between stars and planets." 3Brown dwarfs form like stars. This means they can grow dense and hot enough to collapse under their own gravity. But they never grow dense or hot enough to begin the process of nuclear fusion needed to turn into a star, NASA said. Because of this, brown dwarfs are sometimes called failed stars. 4Many brown dwarfs are similar to gas giant planets and weigh just a few times more than the mass of Jupiter. Others can be much larger. 5The first brown dwarf was discovered in 1995 by researchers from the California Institute of Technology (Caltech). The discovery was made with the help of the institute's Palomar Observatory near San Diego, California. 6But after many years of studying the object, known as Gliese 229B, scientists wondered why its brightness was less than expected for an object of its size. 7New research now shows that the brown dwarf is actually two objects. The observations came from the Very Large Telescope, which sits in a desert area of northern Chile. Those observations showed that one of the brown dwarfs is about 38 times the mass of Jupiter, while the other is 34 times Jupiter's mass. 8In a statement, the researchers said data collected by the telescope suggests the two objects orbit each other every 12 days. That is less than half the time it takes for the moon to orbit the Earth. "The observed brightness levels of the pair match what is expected for two small dim brown dwarfs in this mass range," the statement added. 9The two brown dwarfs are gravitationally linked to each other in what is known as a binary system. Such a situation is commonly observed among stars but is rare for brown dwarfs. 10After the new discovery, the two objects were given new names - Gliese 229Ba and Gliese 229Bb. The brown dwarfs are believed to orbit a star called a red dwarf. The two sit about 19 light-years away from our solar system. A light-year is the distance light travels in one year - about 9.5 trillion kilometers. 11The research was co-led by Jerry Xuan, a graduate student at Caltech. He said in a statement that Gliese 229B was always considered "the poster child" for a brown dwarf. 12"And now we know we were wrong all along about the nature of the object," he added. "It's not one but two. We just weren't able to probe separations this close until now." 13Astronomers had identified brown dwarf pairs before, but never any that orbited each other so closely. The research results recently appeared in a study in the publication Nature. 14The team that discovered Gliese 229B in 1995 included Rebecca Oppenheimer. At the time, she was a Caltech graduate student. She is now an astrophysicist at the American Museum of Natural History in New York City. She was also a member of the latest research team. 15Oppenheimer said, "It shows you how weird the universe is, and how different solar systems are from our own." She added that she sees the new finding as "the most exciting and fascinating discovery" in this area of astrophysics in many years. 16Caltech's Jerry Xuan said the discovery suggests there might be other brown dwarfs closely orbiting each other. He added that he hopes the latest finding can lead to a greater understanding of brown dwarf development. 17"We still don't really know how different brown dwarfs form, and what the transition between a giant planet and a brown dwarf is," Xuan said. 18He added, "This goes to show how complex and messy the star formation process is. We should always be open to surprises." 19I'm Bryan Lynn. 20Bryan Lynn wrote this story for VOA Learning English, based on reports from the Associated Press, Reuters and Caltech. 21_____________________________________________ 22Words in This Story 23straddle - v. to be on both sides of something 24nuclear fusion - n. the process of joining two nuclei to produce energy 25dim - adj. not very bright 26range -n. a series of values 27poster child - n. someone or something that is used to represent a particular quality 28probe - v. to examine something carefully, especially with the goal of finding something hidden 29weird -n. strange or not normal 30fascinating -adj. very interesting 31transition - n. a change from one kind of something to another 32messy - adj. not done wel