In a feat that is critical for India and science, Ahmadabad based lab discovered a planet orbiting a star 600 light years away.
This is a 1st for Indian scientists and is a vindication of India’s space potency.
What the metrics of Exo-planet studies?
Why - Exo-planets are those celestial bodies that orbit stars outside our solar system in clearly defined elliptical paths.
We need to understand how planets form around stars, to understand our solar system better, for which study of exo-planets are key.
Habitability of exo-planets is a keenly studied area, which is mainly based on its distance from its star (the planet should be neither too hot nor too cold).
Indian scientists have been trying to track exo-planets since 2012, but it was only recently that PRL, Ahmadabad became the 1st to achieve the feat.
What - The 1st thing is to understand about exo-planets are their characteristics and fundamental parameters - mass, radius, and atmosphere.
With mass and radius, it is easy to get the density, which will help in making a rough estimate of the planet’s composition.
The challenge - Detecting an exo-planet is very difficult as it is a dull object that will invariably be roaming around the bright spot of its star.
Direct imaging of exo-planets is almost impossible, although new techniques are being evolved by NASA and others.
There are only 5-6 spectrographs around the world that can measure the mass of exo-planets at high precision (radial velocity less than 2 m/s).
India counts itself as one of the few countries that has the instruments to discover and analyse such difficult worlds.
Then, how are exo-planets studied?
How - The presence of a planet will make its star wobble, which can be measured using a precise spectrograph.
This spectrographic reading will help in measuring the mass of the planet.
When the planet passes between its star and Earth, the intensity of light from that star (which reaches the earth) gets minutely dim.
This dip in star’s flux is measured, and this is subsequently employed to estimate the radius of the planet.
What are the observed results of the newly detected exo-planet?
A suspected planet (now been coded as “K2-236b”), was under the observation of the Ahmadabad based lab over 1½ years.
In Jan 2018, scientists conclusively stated that their object of observation was a planet, which was then confirmed by “Mount Abu Space Observatory”.
The planet is said to be composed of 70% iron, ice or silicates and 30% is gas, with about 27 Earth-masses and 6 Earth-radii.
In terms of mass and radius, the planet is akin to Neptune, and it is just one-seventh of the distance away from its star as compared to ‘Sun-Earth distance’.
One year on that planet is about 19.5 Earth-days and surface temperatures average to about 600°C, which thereby makes it uninhabitable.
How does the future of exo-planetary studies in India look?
Indian space scientists have set out with the ultimate aim of detecting planets of close-to-Earth mass (2 to 10 Earth masses).
A new 2.5-m telescope at “Mount Abu Observatory” with a bigger spectrograph is likely to be installed by 2020, and it will be called “PARAS-2”.
PARAS-2 is slated to have the capacity to even measure smaller exo-planets that are just about 2 or 4 times Earth’s mass.
It is also hoped that ISRO will launch some space missions relating to exo-planet studies.
