Dhaka: 9:55 AM, Tue, 16 Oct, 2018

Second earth found just 11 light years away

Mukul : risingbd.com
Publish on: 2017-11-16 4:38:21 PM     ||     Updated: 2017-11-16 8:57:26 PM

Risingbd Desk: A planet the same size as Earth and with a similar surface temperature may be 'the closest known comfortable abode for possible life,' according to a new study.
The newly discovered world, named Ross 128b, was found orbiting a red dwarf star 11 light-years away from Earth.

With current technology, it would take us around 141,000 years to reach the planet.
Although it is currently 11 light-years from Earth, the planet is moving towards us, and is expected to become our nearest stellar neighbour in 'just' 79,000 years - a blink of the eye in cosmic terms.

Astronomers working with the European Southern Observatory's High Accuracy Radial velocity Planet Searcher (HARPS) at the La Silla Observatory in Chile found that the red dwarf star Ross 128 is orbited by a low-mass 'exoplanet' every 9.9 days.

The star was named after the Californian astronomer Frank Elmore Ross who discovered it.

The Earth-sized world is expected to be temperate, with a surface temperature that may also be close to that of the Earth.

Ross 128 is the 'quietest' nearby star to host such a temperate exoplanet.

Study co-author Dr Nicola Astudillo-Defru, of the University of Geneva in Switzerland, said: 'This discovery is based on more than a decade of HARPS intensive monitoring together with state-of-the-art data reduction and analysis techniques.

'Only HARPS has demonstrated such a precision and it remains the best planet hunter of its kind, 15 years after it began operations.'

Red dwarfs are some of the coolest, faintest - and most common - stars in the universe.
These qualities make them very good targets in the search for exoplanets and so they are increasingly being studied.

Lead author Dr Xavier Bonfils, of Université Grenoble in France, named the HARPS programme 'the shortcut to happiness' as it is easier to detect small cool siblings of Earth around these stars, than around stars more similar to the Sun.

But speaking to National Geographic, he added: 'There wasn't a 'eureka' moment here where we were able to suddenly say, wow, we have a planet.

'We accumulated data over many years, and only gradually the signal built up and became significant.'

Many red dwarf stars, including Proxima Centauri, are subject to flares that occasionally bathe their orbiting planets in deadly ultraviolet and X-ray radiation.

But Dr Bonfils said it seems that Ross 128 is a much quieter star, and so its planets may be the 'closest known comfortable abode for possible life.'

He added: 'We definitely need more data before we can say anything conclusive.'
Although it is currently 11 light-years from Earth, Ross 128 is moving towards us and is expected to become our nearest stellar neighbour in 'just' 79,000 years - a blink of the eye in cosmic terms.

Ross 128b will by then take the crown from Proxima b and become the closest exoplanet to Earth.

Speaking to MailOnline, Dr Bonfils explained: 'The star (together with its planets) is moving toward us. All stars move.

'It's hard to perceive in a lifetime but over thousand of years the sky is changing.
'Proxima Centauri will continue to approach us for some time and after a point of closest approach, it will move away for us.

'In the meantime we are getting closer to other stars. And in around 79,000 years, Ross128 will be the closest.'

With the data from HARPS, the team found that Ross 128b orbits 20 times closer than the Earth orbits the sun.

This places it in what astronomers call the ‘Goldilock’s zone’ – getting enough sunshine to be ‘not too hot’ and ‘not too cold’, which would help it support life.

But, despite the proximity, Ross 128b receives only 1.38 times more irradiation than the Earth.

As a result, Ross 128 b's equilibrium temperature is estimated to lie between -60 and 20°C, thanks to the cool and faint nature of its small red dwarf host star, which has just over half the surface temperature of the sun.

The whole planet is also though to be bathed in an eerie red light, experts said, as it is orbiting a red dwarf star.

While the scientists involved in the discovery consider Ross 128b to be a temperate planet, uncertainty remains as to whether the planet lies inside, outside, or on the cusp of the habitable zone, where liquid water may exist on a planet's surface.

Astronomers are now detecting more temperate exoplanets, and the next stage will be to study their atmospheres, composition and chemistry in more detail.

Vitally, the detection of biomarkers such as oxygen in the very closest exoplanet atmospheres will be a huge next step, which ESO's Extremely Large Telescope (ELT) is in prime position to take.

Dr Bonfils added: 'New facilities at ESO will first play a critical role in building the census of Earth-mass planets amenable to characterisation.

'In particular, NIRPS, the infrared arm of HARPS, will boost our efficiency in observing red dwarfs, which emit most of their radiation in the infrared.

'And then, the ELT will provide the opportunity to observe and characterise a large fraction of these planets.'

Dr John Mason, press officer for the British Astronomical Association said the finding was 'incredibly noteworthy.'

He said: 'This is the second nearest exoplanet to the Earth, but it may be more hospitable to life than the closest one.

'The new planet orbits 20 times closer to its star than we do, but because its star is very dim, even though its 20 times closer the conditions would be very similar to conditions we find on earth.

'Red dwarf stars have a very nasty habit of sending out big flares that would erode atmospheres of neighbouring planets.

'This red dwarf, Ross 128 appears to be more stable, and less prone to sending out the big flares that would destroy life.

'What sets this one apart is that it's the second closest, but may be much more suitable for life to emerge and survive than the nearest exoplanet.

'It's a much nicer neighbourhood to grow up in you could say.'

Source: The Mail

risingbd/Nov 16, 2017/mukul