Context
An Indian astronomer has led the PASIPHAE project, which is funded by the world’s leading institutions, for the development of a vital instrument, to survey the sky and to study stars.
- Inter-University Centre for Astronomy and Astrophysics (IUCAA), India, is one of the participants.
About PASIPHAE
- It is a sky surveying project.
- The name of the project is inspired by Pasiphae, the daughter of Greek Sun God Helios, who was married to King Minos.
- The project aims to study the polarisation in the light coming from millions of stars.
- The distances to these stars will be obtained from measurements of the GAIA satellite.
- The survey will use two high-tech optical polarimeters to observe the northern and southern skies, simultaneously.
- It will be helpful for 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).
How the PASIPHAE will be useful?
- The expansion of the universe went through an inflationary phase. This slowdown of expansion of the universe was tried to be explained by scientists.
- A consequence of the inflationary phase is that a tiny fraction of the Cosmic Microwave Background (CMB)radiation should have its imprints in the form of a specific kind of polarisation (known scientifically as B-mode signal).
- All previous attempts to detect this signal met with failure mainly due to the difficulty posed by our galaxy, the Milky Way, which emits copious amounts of polarised radiation and dust clouds.
- The PASIPHAE survey will measure starlight polarisation over large areas of the sky.
- This data along with GAIA distances to the stars will help create a 3-Dimensional model of the distribution of the dust and magnetic field structure of the galaxy. Such data can help remove the galactic polarised foreground light and enable astronomers to look for the elusive B-mode signal.
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Wide Area Linear Optical Polarimeter (WALOP)
- It is an instrument to detect polarised light signals emerging from the stars along high galactic latitudes.
- WALOP was planned in 2013.
- It will be capable of capturing images within ½ ° by ½ ° area of the sky during every exposure.
- WALOP follows the single-shot photometry principle.
- Under this, at any given time, the data from a portion of the sky under observation will be split into four different channels. Depending on how light passes through the four channels, the polarisation value from the star is obtained.
- The development of the instrument is in an advanced stage currently and progressing at the instrumentation facility in IUCAA.
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