New exoplanet No. 3 discovered by NASA

Published: 17th Jan, 2019

NASA’s planet-hunting probe Transiting Exoplanet Survey Satellite (TESS), has discovered a new exoplanet named HD 21749b outside our solar system.
This is the third new planet confirmed by the TESS since its launch in April 2018. The other two being Pi Mensae b and the LHS 3844b.

Context

NASA’s planet-hunting probe Transiting Exoplanet Survey Satellite (TESS), has discovered a new exoplanet named HD 21749b outside our solar system.
This is the third new planet confirmed by the TESS since its launch in April 2018. The other two being Pi Mensae b and the LHS 3844b.

About

Main findings

The exoplanet orbits a bright, nearby dwarf star about 53 light years away, in the constellation
HD 21749b orbits around its star in 36 days, compared to the two other planets — Pi Mensae b, a “super-Earth” with a 6.3-day orbit, and LHS 3844b, a rocky world that speeds around its star in just 11 hours.
It’s the coolest small planet that has been discovered so far which revolves around a star outside of our own solar system.
The planet is about three times the size of the earth, which puts it in the category of a “sub-Neptune.”

What is Transiting Exoplanet Survey Satellite Mission (TESS)?

TESS is a NASA-sponsored Astrophysics Explorer-class mission that is performing a 2-year all-sky survey to search for planets transiting nearby stars.
It will discover planets smaller than Neptune that transit stars bright enough to enable follow-up spectroscopic observations that can provide planet masses and atmospheric compositions
It will monitor about 200,000 main-sequence dwarf stars to detect periodic drops in brightness caused by planetary transits.

Is it the first mission to explore the exoplanets?

No, earlier NASA's Kepler Mission conducted a statistical transit survey designed to determine the frequency of Earth-sized planets around other stars.
Kepler revealed thousands of exoplanets orbiting stars in its 115 square degree field-of view, which covered about 0.25 percent of the sky.
While Kepler was revolutionary in its finding that Earth-to-Neptune-sized planets are common, the bulk of the stars in the Kepler field lie at distances of hundreds to thousands of parsecs, making it difficult to obtain ground-based follow-up observations for many systems.

What is speciality of TESS over Kepler Mission?

The TESS Mission is designed to survey over 85% of the sky (an area of sky 400 times larger than covered by Kepler) to search for planets around nearby stars (within ~200 parsec).
TESS stars will typically be 30-100 times brighter than those surveyed by the Kepler satellite.
Planets detected around these stars will therefore be far easier to characterize with follow-up observations, resulting in refined measurements of planet masses, sizes, densities, and atmospheric properties.

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