Type: Prelims Only

A group of international astrophysicists have identified cloud bands on the surface of Luhman 16A, one of a pair of binary brown dwarfs in the Vela constellation.

Space terminology has gained importance in prelims. The Luhman 16A coupled with few more examples of space concepts like binary star and dwarf star are discussed in this newscard.

Luhman 16A

• Luhman 16 is a binary star system, the third closest system to the Sun after Alpha Centauri and Barnard’s star.
• At a distance of about 6.5 light-years from the Sun, this pair of brown dwarfs referred to as Luhman 16A and Luhman 16B orbit each other, casting a dim light.
• Brown dwarfs are also called failed stars because their masses are intermediate to the largest planets and the smallest main sequence stars.
• Their masses being too small, they are unable to sustain fusion of their hydrogen to produce energy.
• It is believed that some of the more massive brown dwarfs fuse deuterium or lithium and glow faintly.

The cloud band over Luhman

• The group, by using the Very Large Telescope at European Southern Observatory, Chile, found that Luhman 16A had band-like clouds in its atmosphere, whereas the same was not true of Luhman 16B.
• Many astronomers detected polarization of brown dwarfs.
• But what is special in the newest study of Luhman 16 is that the researchers have found the actual structure of the clouds — that they form bands over one of the pair.
• Understanding the cloud system over a brown dwarf can shed light on the pressure, temperature and climate on the surface of the celestial body.

Why it has made into a headline?

• The researchers have used an idea put forth nearly two decades ago by Indian astrophysicist Sujan Sengupta, who works at the Indian Institute of Astrophysics, Bengaluru.
• Sengupta had propounded the light emitted by a cloudy brown dwarf, or reflected off an extrasolar planet, will be polarized.
• He then suggested that a polarimetric technique could serve as a potential tool to probe the environment of these objects.

Back2Basics: Binary Star System

• A binary star is a star system consisting of two stars orbiting around their common barycenter.
• Systems of two or more stars are called multiple star systems.
• These systems, especially when more distant, often appear to the unaided eye as a single point of light, and are then revealed as multiple by other means.
• Binary star systems are very important in astrophysics because calculations of their orbits allow the masses of their component stars to be directly determined.

China has successfully launched a new rocket and prototype spacecraft in a major test of the country’s ambitions to operate a permanent space station and send astronauts to the Moon.

Can you recall the historical link between the name “The Long March” and China’s History.

The Long March 5B

• Long March 5 or Chang Zheng 5 is a Chinese heavy-lift launch system developed by the China Academy of Launch Vehicle Technology (CALT).
• It is the first Chinese launch vehicle designed from the ground up to focus on non-hypergolic liquid rocket propellants.
• The maximum payload capacities of the base variant are ~25,000 kilograms to Low Earth Orbit and ~14,000 kilograms to Geosynchronous Transfer Orbit.
• The spaceship is expected to transport astronauts to a space station that China plans to complete by 2022 — and eventually to the Moon. It will have a capacity for a crew of six.

Back2Basics: Geosynchronous Transfer Orbit

• About 35,786 kilometers above the Earth’s surface, satellites are in geostationary orbit. From the center of the Earth, this is approximately 42,164 kilometers. This distance puts it in the high Earth orbit category.
• At any inclination, a geosynchronous orbit synchronizes with the rotation of the Earth.
• While geosynchronous satellites can have any inclination, the key difference to geostationary orbit is the fact that they lie on the same plane as the equator.
• GTO is a an elliptical orbit used to transfer between two circular orbits of different radiuses in the same plane—used to reach geosynchronous or  geostationary orbit using high-thrust chemical engines.