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2006 VW139/288P: Astronomers spot strange binary asteroid with comet-like features

International team of astronomers using NASA’s Hubble Space Telescope have spotted an unusual object called 2006 VW139/288P having two asteroids orbiting each other with comet-like features. These include bright halo of material, called a coma, and long tail of dust. The odd object is first known binary asteroid that is also classified as a main-belt comet.

Asteroids and comets

Asteroids and comets are believed to be ancient remnants of earliest years of formation of our solar system more than four billion years ago. Asteroids are known as inactive, rocky body orbiting the Sun. Comets are bodies of ice, rock and organic compounds that can be several miles in diametre and they can be at times active. Ice of comets can vaporise in sunlight forming an atmosphere (coma) of dust and gas and, sometimes, a tail of dust and/or gas.

2006 VW139/288P

Hubble was used to image asteroid in September 2016 just before it made its closest approach to Sun. The images revealed that it was actually not one, but two asteroids of almost the same mass and size, orbiting each other at a distance of 96 km.

It was discovered by Spacewatch in November 2006 and its possible cometary activity was seen in November 2011 by Pan-STARRS after that it was given comet designation of 288P. The more recent Hubble observations revealed ongoing activity in binary system.

The combined features of binary asteroid are wide separation, near-equal component size, high eccentricity orbit, and comet-like activity. These make it unique among few known binary asteroids that have a wide separation.

Significance: Understanding of 2006 VW139/288P’s origin and evolution may provide new insights into early days of solar system. The main-belt comets may help to answer how water came to a bone-dry Earth billions of years ago. As it is different from all other known binary asteroids, it will also help to answer some questions about how common such systems are in the asteroid belt.

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Scientists for first time observe Optical polarisation phenomenon of fast spinning star

Scientists for first time have observed Optical polarisation phenomenon (polarised light emitted by rapidly rotating stars) after it was predicted by Indian astrophysicist and Nobel laureate Subrahmanyan Chandrasekhar 70 years ago.

Optical polarisation phenomenon is a measure of the orientation of the oscillations of a light beam to its direction of travel.

Key Facts

The phenomenon was observed using High Precision Polarimetric Instrument (HIPPI), world’s most sensitive astronomical polarimeter to detect polarised light from Regulus, one of brightest stars in night sky about 79 light years away.

The equipment provided unprecedented insights into star, which is in constellation Leo. It allowed scientists to determine its rate of spinning and orientation in space of star’s spin axis. It was observed that Regulus is rotating so quickly with a spin rate of 96.5% of angular velocity (approximately 320 kilometres per second) for break-up.

Background

Subrahmanyan Chandrasekhar in 1946 had first predicted that some stars could be emitting polarised light from their edges. Based on his idea, Astronomers J Patrick Harrington and George W Collins II predicted in 1968 predicted that polarised light will be emitted by rapidly rotating star because its shape gets distorted into a squished oblate shape as it spins too fast.

Subrahmanyan Chandrasekhar

He was Indian American astrophysicist who was awarded the 1983 Nobel Prize for Physics with William A. Fowler for his theoretical studies of physical processes of importance to structure and evolution of stars. His mathematical treatment of stellar evolution had yielded many of best current theoretical models of later evolutionary stages of massive stars and black holes. The Chandrasekhar limit (maximum mass of a stable white dwarf star) has been named after him.

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