Science and Technology Current Affairs – 2017

Latest Science & Technology Current Affairs 2015-2016; current developments in Science and Technology 2015-2016 all important national / international updates in science and tech and events for the year 2015-2016.

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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Scientists create first global map of water on Moon

Scientists from Brown University in US have created first map of water trapped in uppermost layer of Moon’s soil. The  was build using NASA’s Moon Mineralogy Mapper onboard of India’s Chandrayaan-1 spacecraft.

The map builds on initial discovery of water and related molecule — hydroxyl (consists of one atom each of hydrogen and oxygen) in lunar soil in 2009. It may prove useful to future lunar explorers.

Water Presence on Moon

The signature of water is present nearly everywhere on lunar surface and not limited to polar regions as it was previously reported. The distribution of waster on moon is largely uniform rather than splotchy. The way in which it is distributed across Moon gives clues about its source.

The amount of water on moon increases toward poles and does not show significant difference among distinct compositional terrains. It reaches a maximum average of around 500 to 750 parts per million (ppm) in higher latitudes, less than what is found in sands of Earth’s driest deserts.

However, its concentrations gradually decrease toward equator. This pattern is consistent with implantation via solar wind from Sun, which can form hydroxyl (OH) and molecular water once emplaced.

Bulk of water mapped in this study can be attributed to solar wind with some exceptions. For example, higher-than-average concentration of water was found in lunar volcanic deposits near Moon’s equator, where water in surrounding soil was scarce. In this case, it is assumed that water comes from deep within Moon’s mantle and erupted to surface in lunar magma rather than coming from solar wind.

The concentration of water also changes over course of lunar day at latitudes lower than 60 degrees, going from wetter in early morning and evening to nearly bone dry around lunar noon. The fluctuation can be as much as 200 ppm.

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