2019 – Posted in: Daily News

HOW NEW STARS ARE BORN

For: Mains

Topics covered:

How new stars are born?
Death of a giant star
What is gravitational lensing?
What are the effects of lensing? Why is lensing useful?
About James Webb Space Telescope

News Flash

Using NASA’s James Webb Space Telescope as a sort of time machine, researchers plan to investigate how new stars are born, with the help of a natural phenomenon called “gravitational lensing”.

The phenomenon occurs when a huge amount of matter (a massive galaxy or cluster of galaxies) creates a gravitational field that distorts and magnifies the light from objects behind it, but in the same line of sight.

In effect, these are natural, cosmic telescopes; they are called gravitational lenses. These large celestial objects will magnify the light from distant galaxies that are at or near the peak of star formation.

The effect allows researchers to study the details of early galaxies too far away to be seen otherwise with even the most powerful space telescopes.

What is gravitational lensing?

Gravitational lensing works in an analogous way and is an effect of Einstein’s theory of general relativity – simply put, mass bends light.

The gravitational field of a massive object will extend far into space, and cause light rays passing close to that object (and thus through its gravitational field) to be bent and refocused somewhere else.

The more massive the object, the stronger its gravitational field and hence the greater the bending of light rays – just like using denser materials to make optical lenses results in a greater amount of refraction.

Gravitational lensing happens on all scales – the gravitational field of galaxies and clusters of galaxies can lens light, but so can smaller objects such as stars and planets.

Gravitational Lensing

What are the effects of lensing?

Light rays coming towards us from distant galaxies will pass through the gravitational field of dark matter and hence will be bent by the lensing effect.

Why is lensing useful?

Gravitational lensing is useful to cosmologists because it is directly sensitive to the amount and distribution of dark matter.
In between the Earth and numerous galaxies, there is a mysterious entity called dark matter, which is invisible, but it does have mass, making up around 85% of the mass of the Universe.
Lensing help astronomers to work out exactly how much dark matter there is in the Universe as a whole, and also how it is distributed.
Lensing has also been used to help verify the existence of dark matter itself.

James Webb Space Telescope

The telescope is named for James E. Webb, who was the administrator of NASA from 1961 to 1968 and played an integral role in the Apollo program.

The James Webb Space Telescope (JWST or “Webb”) is a space telescope that is planned to be the successor to the Hubble Space Telescope.

Webb’s instruments are contained within the Integrated Science Instrument Module (ISIM) which is one of three major elements that comprise the James Webb Space Telescope Observatory flight system. The others are the Optical Telescope Element (OTE) and the Spacecraft Element (Spacecraft Bus and Sunshield).

The ISIM is the heart of the James Webb Space Telescope. The ISIM Includes The Following Instruments:

Near-Infrared Camera, or NIRCam – provided by the University of Arizona
Near-Infrared Spectrograph, or NIRSpec – provided by ESA, with components provided by NASA/GSFC.
Mid-Infrared Instrument, or MIRI – provided by the European Consortium with the European Space Agency (ESA), and by the NASA Jet Propulsion Laboratory (JPL)
Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph, or FGS/NIRISS – provided by the Canadian Space Agency.

Source: Indian Express/ NASA

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