PASIPHAE Sky Surveys
Source : Indian Express
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Why in News ?

The project has been funded by the world’s leading institutions, signalling India’s growing expertise in building complex astronomical instruments.

PASIPHAE Sky Surveys

• Polar-Areas Stellar-Imaging in Polarisation High-Accuracy Experiment (PASIPHAE) is an international collaborative sky surveying project.
• Scientists aim to study the polarisation in the light coming from millions of stars.
• The name is inspired from Pasiphae, the daughter of Greek Sun God Helios, who was married to King Minos.
• Survey will use two high-tech optical polarimeters to observe the northern and southern skies, simultaneously.

Key Facts

• PASIPHAE survey will measure starlight polarisation over large areas of the sky.
• It will help create a 3-Dimensional model of the distribution of the dust and magnetic field structure of the galaxy.
• The development of a vital instrument which will be used in upcoming sky surveys to study stars, is being led by an Indian astronomer.
• PASIPHAE will focus on capturing starlight polarisation of very faint stars that are so far away that polarisation signals from there have not been systematically studied.
• The distances to these stars will be obtained from measurements of the GAIA satellite.
• By combining these data, astronomers will perform a maiden magnetic field tomography mapping of the interstellar medium of very large areas of the sky using a novel polarimeter instrument known as WALOP (Wide Area Linear Optical Polarimeter).
• The Infosys Foundation, India, Stavros Niarchos Foundation, Greece and USA’s National Science Foundation have each provided a grant of $1 million combined with contributions from the European Research Council and the National Research Foundation in South Africa.

Wide Area Linear Optical Polarimeter (WALOP)

• An instrument, when mounted on two small optical telescopes, that will be used to detect polarised light signals emerging from the stars along high galactic latitudes.

  

• WALOP each will be mounted on the
  • 1.3-metre Skinakas Observatory, Crete
  • 1-metre telescope of the South African Astronomical Observatory located in Sutherland.
• They will be unique instruments offering the widest ever field of view of the sky in polarimetry.
• Working Method
  • WALOP will operate on the principle that at any given time, the data from a portion of the sky under observation will be split into four different channels.
  • Depending on the manner in which light passes through the four channels the polarisation value from the star is obtained.
  • That is each star will have four corresponding images which when stitched together will help calculate the desired polarisation value of a star.

Polarimetry has played a key role in the development of modern astronomy, providing insight into physical processes occurring in systems that range from our own solar system to high-redshift galaxies.

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