Pluto lost its status as a planet decades ago. But it is still the centre of attraction for astronomers the world over. A team of astronomers recently measured the atmospheric pressure on the surface by observing an occultation using the 3.6m Devasthal optical telescope, India's largest optical telescope, and the 1.3-m Devasthal Fast Optical Telescope (DFOT) telescope.
The telescopes are located in Nainital, Uttarakhand.
The results are based on the last measured occultation in June 2020. The astronomers have measured 12 such events between 1988 and 2016.
The found that the atmospheric pressure on the surface of Pluto is more than 80,000 times less than the atmospheric pressure at mean sea level on Earth.
In astronomy, an occultation happens when a celestial object gets hidden from the view of the observer due to another celestial object passing in between them.
The international team of scientists included members from Aryabhatta Research Institute of Observational Sciences (ARIES). They used signal-to-noise ratio light curves obtained from the sophisticated instruments used in the observations to derive an accurate value of Pluto's atmospheric pressure at its surface.
The research published in ‘Astrophysical Journal Letters' showed that since mid-2015, Pluto's atmosphere is in a plateau phase close to peak and is in excellent agreement with the model values calculated earlier by the Pluto volatile transport model in 2019. The team explained further that this occultation was particularly timely as it can test the validity of the current models of Pluto's atmosphere evolution.
The study confirms earlier findings that Pluto suffers intense seasonal episodes because of large depression known as Sputnik Planitia. Pluto's poles remain, for decades, in permanent sunlight or darkness over its 248-year long orbital period leading to strong effects on its Nitrogen (N2) atmosphere that is mainly controlled by vapour pressure equilibrium with the surface N2 ice.
As Pluto is now moving away from the Galactic plane as seen from Earth, stellar occultation by the dwarf planet are becoming increasingly rare, making this event a decisive one.
