Published: Thu, August 10, 2017
Science | By Hubert Green

Hertfordshire scientists discover two potentially habitable planets

Hertfordshire scientists discover two potentially habitable planets

The scientists discovered the potentially habitable planets after observing the wobbles in the movement of Tau Ceti, caused by its orbiting planets. But doing so might be a risky expedition. Researchers concede, however, that a massive debris disc around the star probably reduces the current habitability of the planets, due to intensive bombardment by asteroids and comets.

Astronomers are especially excited by the discovery because the planets are as small as 1.7 times our size. These planets have masses as low as 1.7 Earth mass, making them among the smallest planets ever detected around nearby sun-like stars. This "wobble" method of planet finding measures the influence of gravitational interaction on a star. These planets orbit around habitable zone of the nearest Sun-like star Tau Ceti, some 12 light years away.

Smaller planets require extra precision since the wobble is smaller and they can be harder to spot.

This star supports a multi-planetary solar system that's been a point of focus for astronomers for some time, and now, an worldwide team of researchers led by the University of Hertfordshire in the United Kingdom have revealed something new about the system: it may include four Earth-sized planets, two of which could be habitable.

"Our detection of such weak oscillations is an important milestone in the search for analogues of the Earth and understanding the viability of the Land by comparison with them". Much larger stars than the sun tend to be more unstable, releasing radiation and pulsing novae of heat that would make the development of life on a planet over millions of years impossible. Tau Ceti, a favourite destination of science fiction writers, is very similar to the sun both in size and brightness.

Like the Sun, she has a "life zone" - the narrow area around it, where conditions favorable for life.

However, just being in the habitable zone around an ideal star does not guarantee that the planet will support life. Life-zone planets can have oceans, lakes and rivers. And, as before, the claim that tau Ceti e and f might reside in the habitable zone is already being contested. The team's revisiting of the subject resulted in eliminating one of those planets and downsizing the other four. The earth located halfway between the middle of the zone, fit for life, and her domestic turn.

The data were obtained by using the HARPS spectrograph (European Southern Observatory, Chile) and Keck-HIRES (W. M. Keck Observatory, Mauna Kea, Hawaii).

The findings are due to appear in an upcoming edition of The Astrophysical Journal.

Mikko Tuomi, another researcher at the University of Herefordshire, explained, "We came up with an ingenious way of telling the difference between signals caused by planets and those caused by star's activity".

The researchers painstakingly improved the sensitivity of their techniques and were able to rule out two of the signals the team had identified in 2013 as planets.

'We realized that we could see how the star's activity differed at different wavelengths and use that information to separate this activity from signals of planets, ' said Dr Tuomi.

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