Mystery of the Massive Brown Dwarf: How It Poses a Challenge to the Understanding of Star Formation and Evolution

Brown dwarfs are objects that are too big to be planets, but too small to be stars. They have masses between 13 and 80 times that of Jupiter, and they do not have enough nuclear fusion in their cores to shine like stars.

Powerful telescopes can detect the infrared light and radio waves that they can generate.

The Zwicky Transient Facility (ZTF) was recently used by astronomers to find a new, enormous brown dwarf.

New brown dwarf discovered

(Photo : NASA/ via Unsplash)

The new brown dwarf, named ZTF J2020+5033, was discovered by a team of astronomers led by Kareem El-Badry of the California Institute of Technology (Caltech).

They were searching for low-mass eclipsing binaries, which are pairs of stars that orbit each other and block each other's light periodically.

They then found a system consisting of an M-dwarf star and a brown dwarf, which they confirmed using data from other telescopes and instruments.

The system is located about 445 light years away from Earth, and has an orbital period of only 1.9 hours. This means that the brown dwarf passes in front of the star every 1.9 hours, causing a dip in the star's brightness that can be measured by ZTF.

ZTF is a survey that uses a camera mounted on the Samuel Oschin Telescope at Palomar Observatory in California.

It scans the sky every night for transient objects, such as supernovae, asteroids, and eclipsing binaries.

The astronomers analyzed the light curves of ZTF J2020+5033 and estimated the properties of the brown dwarf and the star.

They found that the brown dwarf is about 80 times more massive than Jupiter and has a radius similar to Jupiter's.

The star is about 13% more massive than the sun and has a radius of about 18% of the sun's. The system is also very old, between 5 and 13 billion years old.

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Importance of the new brown dwarf

The new brown dwarf is important for several reasons. First, it is one of the most massive brown dwarfs ever found, close to the boundary between brown dwarfs and very low-mass stars.

Second, it is in a very short-period orbit around a low-mass star, which is rare among known systems with transiting brown dwarfs.

Third, it provides clues about the formation and evolution of such systems, as well as the effects of magnetic braking and tidal interactions.

Magnetic braking is a process that slows down the rotation of stars and planets due to their magnetic fields interacting with the surrounding plasma.

Tidal interactions are forces that arise from the gravitational attraction between two bodies that are close to each other. Both processes can affect the orbital dynamics and shape of the bodies involved.

The astronomers suggested that ZTF J2020+5033 was formed by a different mechanism than most other brown dwarfs, which are thought to form like stars from collapsing clouds of gas and dust.

They proposed that ZTF J2020+5033 was formed by disk fragmentation, which occurs when a disk of gas and dust around a young star becomes unstable and breaks into clumps that can form planets or brown dwarfs.

They also suggested that magnetic braking and tidal interactions have played a significant role in shaping the orbit and properties of ZTF J2020+5033 over time.

The astronomers plan to conduct further observations of ZTF J2020+5033 using other telescopes and instruments, such as the James Webb Space Telescope (JWST), which will be launched in 2024.

JWST will be able to study the system in more detail and reveal its atmospheric composition, temperature, and chemistry.

ZTF J2020+5033 is an exciting discovery that showcases the power of ZTF and other surveys to find rare and interesting objects in the sky. It also opens new avenues for research on brown dwarfs and their formation and evolution.

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