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The Detecting of Rare “UV-bright Stars” and “The Hum of the Universe”

Astronomers use UVIT to discover a large number of hot, ultraviolet bright stars in the Milky Way. UVIT is an ultraviolet imaging telescope. It is placed in the Astrosat satellite. Astrosat is India's first multi-wavelength space satellite. Highlights: Astronomers have successfully distinguished ultraviolet bright star clusters from relatively cold red giant stars and other main-sequence stars. Thirty-four ultraviolet bright stars were discovered using UVIT. From these images, the research team also derived the properties of the stars, such as brightness, temperature, and radius. The derived properties of the stars are placed in the Herzpron-Russell diagram. The graph shows the relationship between the absolute size and brightness of stars and their effective temperature (or star classification). This figure was first created in 1910 by Ejnar Hertzsprung and Henry Norris Russell. Ultraviolet bright stars are brighter than horizontal branches and bluer than red giant branches. According to astronomers, the core of the discovered star is almost exposed. This makes them very hot. They evolved from the solar phase called the "horizontal branching star". Such a star has no shell. These stars are like the sun, in the later stages of evolution. In addition to UVIT, astronomers also use Gaia telescopes and space telescopes to identify stars. Ultraviolet rays: Ultraviolet imaging telescope is a three-in-one imaging technology. It can observe near-ultraviolet, visible and far-ultraviolet wavelengths. UVIT has two telescopes. One works in the visible light range, from 320 nanometers to 550 nanometers. The other works at near-ultraviolet wavelengths, which is 200-300 nanometers. UVIT is three times better than NASA's GALEX. GALEX is Galaxy Evolution Explorer. This is the ultraviolet space telescope launched in 2003 and decommissioned in 2013. To date, UVIT has made 1,166 observations of 800 unique sources of celestial bodies. It has explored several star clusters and mapped large and small satellite galaxies near the Milky Way called the Magellanic Cloud. Astrosat was launched in 2015. It is the first multi-wavelength space observatory in India. Its emission is to observe the universe in ultraviolet, visible light, and low-energy and high-energy X-rays. This mission makes ISRO an exclusive club for countries that currently have observatories. They are the United States, Japan, the European Space Agency and Russia.

The North American Nanohetz Gravitational Wave Observatory (NANOGrav) discovered the hum of the universe. According to the researchers, the hum is generated by gravitational waves. Highlights: The hum of the universe comes from a dead star called a "pulsar". These stars are basically neutron stars. They are oriented in such a way that they emit radio waves from their poles as they rotate. This is the first time a hum has been heard from a pulsar collision. Early scientists have observed this buzzing sound. However, they come from the merger of black holes. The LIGO Observatory has discovered the hum of black hole mergers. LIGO is a gravitational wave observatory for laser inferring instrument. The discovery of the humming sound of pulsars will be an important step for the members of the pulsar timing array. When black holes collide, a similar buzzing sound is produced. This sound is called black hole hum. In a year, on average, more than 100,000 black holes merge in the universe. NANOGrav is the North American gravitational wave nanohertz observatory. The main purpose of NANOGrav is to detect gravitational waves. The implementation of the project is by Parkes Pulsar timing array, international Pulsar timing array and European Pulsar timing array. Pulsar timing array: It is a program for regular and regular observation of the millisecond pulsar array with regular distribution. A millisecond pulsar is a pulsar whose rotation period is less than about ten milliseconds. A millisecond pulsar is a pulsar whose rotation speed is less than ten milliseconds. Indian Pulsar Timing Array: It is a project of the National Radio Astrophysics Center of the Tata Institute of Basic Research. It aims to detect nano-hertz gravitational waves through precise timing.

Words by - Vinuri Arambepola (Faculty of Agriculture)

Design by - Kasun Madushan (Faculty of Engineering)