Context:
Researchers have used James Webb Space Telescope observations to conduct detailed examinations of the atmospheric conditions on pairs of brown dwarfs.
Relevance:
GS III: Science and Technology
Dimensions of the Article:
- Brown Dwarfs
- What is NASA’s James Webb Telescope?
Brown Dwarfs
Definition and Characteristics:
- Size Range: Brown dwarfs are celestial bodies that fall between the size of giant planets (like Jupiter) and small stars.
- Composition: They accumulate material similar to stars but do not reach the mass required to sustain nuclear fusion in their cores.
- Atmosphere: Their atmospheres can contain clouds made of hot silicate particles rather than water clouds found on Earth, due to their higher temperatures.
- Elemental Composition: They retain lighter elements like hydrogen and helium more effectively than planets, resulting in a relatively low metal content.
Why They Are Not Stars:
- Insufficient Mass: Brown dwarfs do not have enough mass to achieve the high pressures and temperatures needed to initiate nuclear fusion in their cores.
- “Failed Stars”: Due to their inability to sustain nuclear fusion, they are often referred to as “failed stars.”
Comparison with Planets and Stars:
- Similar to Stars: Brown dwarfs accumulate material in a manner similar to stars, with a dense core surrounded by a gaseous atmosphere.
- Unlike Planets: Unlike planets, brown dwarfs hold onto their lighter elements more effectively and have a more substantial mass, but they do not shine like stars due to the lack of nuclear fusion.
Significance:
- Astrophysical Research: Brown dwarfs bridge the gap between stars and planets and help scientists understand the processes of stellar formation and evolution.
- Observational Studies: They are studied using various telescopes to understand their atmospheric composition, temperature, and other physical characteristics.
What is NASA’s James Webb Telescope?
- The telescope has been in the works for years. NASA led its development with the European Space Agency (ESA) and the Canadian Space Agency.
- It was launched aboard a rocket on December 25, 2021, and is currently at a point in space known as the Sun-Earth L2 Lagrange point, approximately 1.5 million km beyond Earth’s orbit around the Sun.
- Lagrange Point 2 is one of the five points in the orbital plane of the Earth-Sun system.
- Named after Italian-French mathematician Josephy-Louis Lagrange, the points are in any revolving two-body system like Earth and Sun, marking where the gravitational forces of the two large bodies cancel each other out.
- Objects placed at these positions are relatively stable and require minimal external energy or fuel to keep themselves there, and so many instruments are positioned here.
- L2 is a position directly behind Earth in the line joining the Sun and the Earth. It would be shielded from the Sun by the Earth as it goes around the Sun, in sync with the Earth.
What is the mission of the James Webb Space Telescope?
NASA says the James Webb Space Telescope will be “a giant leap forward in our quest to understand the Universe and our origins”, as it will examine every phase of cosmic history: from the Big Bang to the formation of galaxies, stars, and planets to the evolution of our own Solar System.
The science goals for the Webb can be grouped into four themes.
- To look back around 13.5 billion years to see the first stars and galaxies forming out of the darkness of the early universe.
- To compare the faintest, earliest galaxies to today’s grand spirals and understand how galaxies assemble over billions of years.
- To see where stars and planetary systems are being born.
- To observe the atmospheres of extrasolar planets (beyond our solar system), and perhaps find the building blocks of life elsewhere in the universe. The telescope will also study objects within our own Solar System.
-Source: Indian Express
