News Break: Planet with Mass of Earth Orbiting a Star in Alpha Centauri— Nearest Star System

 

           

 

European astronomers have discovered a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system — the nearest to Earth. It is also the lightest exoplanet ever discovered around a star like the Sun. The planet was detected using the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile. Alpha Centauri A is the brightest component, Alpha Centauri B is the slightly fainter second star and Alpha Centauri C is the much fainter Proxima Centauri. Proxima Centauri is slightly closer to Earth than A or B and hence is formally the closest star.

“This is the first planet with a mass similar to Earth ever found around a star like the Sun. Its orbit is very close to its star and it must be much too hot for life as we know it,” adds Stéphane Udry (Geneva Observatory), a co-author of the paper and member of the team, “but it may well be just one planet in a system of several. Our other HARPS results, and new findings from Kepler, both show clearly that the majority of low-mass planets are found in such systems.”

Alpha Centauri is one of the brightest stars in the southern skies and is the nearest stellar system to our Solar System — only 4.3 light-years away. It is actually a triple star — a system consisting of two stars similar to the Sun orbiting close to each other, designated Alpha Centauri A and B, and a more distant and faint red component known as Proxima Centauri.

Since the nineteenth century astronomers have speculated about planets orbiting these bodies, the closest possible abodes for life beyond the Solar System, but searches of increasing precision had revealed nothing. Until now.

“Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days,” says Xavier Dumusque (Geneva Observatory, Switzerland and Centro de Astrofisica da Universidade do Porto, Portugal), lead author of the paper. “It’s an extraordinary discovery and it has pushed our technique to the limit!”

HARPS measures the radial velocity of a star — its speed towards or away from the Earth — with extraordinary precision. A planet in orbit around a star causes the star to regularly move towards and away from a distant observer on Earth. Due to the Doppler effect, this radial velocity change induces a shift of the star’s spectrum towards longer wavelengths as it moves away (called a redshift) and a blueshift (towards shorter wavelengths) as it approaches. This tiny shift of the star’s spectrum can be measured with a high-precision spectrograph such as HARPS and used to infer the presence of a planet.

The European team detected the planet by picking up the tiny wobbles in the motion of the star Alpha Centauri B created by the gravitational pull of the orbiting planet. The effect is minute — it causes the star to move back and forth by no more than 51 centimetres per second (1.8 km/hour), about the speed of a baby crawling. This is the highest precision ever achieved using this method.

Alpha Centauri B is very similar to the Sun but slightly smaller and less bright. The newly discovered planet, with a mass of a little more than that of the Earth, is orbiting about six million kilometres away from the star, much closer than Mercury is to the Sun in the Solar System. The orbit of the other bright component of the double star, Alpha Centauri A, keeps it hundreds of times further away, but it would still be a very brilliant object in the planet’s skies.

The first exoplanet around a Sun-like star was found by the same team back in 1995 and since then there have been more than 800 confirmed discoveries, but most are much bigger than the Earth, and many are as big as Jupiter. The challenge astronomers now face is to detect and characterise a planet of mass comparable to the Earth that is orbiting in the habitable zone around another star. The first step has now been taken.

“This result represents a major step towards the detection of a twin Earth in the immediate vicinity of the Sun. We live in exciting times!” concludes Xavier Dumusque

The results will appear online in the journal Nature on 17 October 2012.

 

           

The Daily Galaxy via ESO.org

Comments

[Mitchell Manley]

lets send a probe there.

[Relentless]

Absolutely amazing!!!

Alpha Centauri? Earth-sized planet!?! That was right under our own noses all along! This is truly incredible! Plus, with the techniques for finding smaller planets becoming even better over time, I can only imagine that maybe half (or more) of all the sun-like stars out there actually have planets the size of Earth, with maybe 10-20% of them being "potentially" habitable. By "potentially" habitable I mean something along the lines of Mars (not some highly inhospitable place for us like Venus, Titan, Sedna, or that graphite/diamond exo-planet just found).

I can only imagine how many more of our next-door neighbors will turn up as having Earth-sized planets in the next decade. The chances of simple life being abundant in the universe has been skyrocketed with this.

On a side note: some wicked science-fiction twist for our space-colonizing future now looms on the horizon.

[mark rodriguez]

Could it be possible for this specific planet to develope some kind Of life as we know It during the perioD of time that is not expose to its sun and then hybernate during the exposure period?

[PghPanther]

An impressive find to detect that size/mass of a planet from that far away........

Even though it may be a lifeless like Mercury due to the proximity to its main star............the fact that we keep finding planets outside of our solar system is following the trend of previous evidence..........

Allow me to explain.........

At one time we thought the earth was the only planet but soon found other wanders in the skies in ancient times......in which we found out where other planets within our own solar system.......

At one time we thought the sun was the only star..........but turns out there are billions of them.........

At one time we through we were the only solar system.......turns out there are many more of them perhaps billions as well……......

We thought at one time our galaxy was the whole universe.............turns out there are billions of galaxies too…….

So............would it not be reasonable to acknowledge the potential of billions of earth like planets exist throughout the universe and that perhaps some form of life has evolved on many of those?

Our discoveries really put things in prospective as to how we should think of our planet and species...........unique and special within our own corner of the galaxy and universe..…..but in no way are we in a privileged position over the rest of the universe....

[Brian]

I had a raging nerdgasm until I read "Its orbit is very close to its star and it must be much too hot for life as we know it."

[Bob]

It's time to send an expedition there and make contact with the Na'vi.

[Jurriaan]

Great find. Too bad it is in the furnace zone :) How about all that folklore and UFO stories that claim that they are coming from the Centauri system... might be worth taking a look into that.

By the way: a planet so close to its star will probably be locked with the same face to that star. I foresee a possibility of specialistic life occuring in the terminator zone of that planet. Ranging from pole to pole a whole band of semi shadow that has ups and downs with the movement of the other two stars in the system lighting it up like day and night here on Earth.

[Yordan]

We got the first signs of existance of similar/same/better stelar systems like ours.

It is time to make not a step, but a leap into the Space programs starting to design inter-stelar spaceships.

Go to drawing boards of fast propulsion engines guys !

[Trantorian]

If we don't kill ourselves, these next centuries will see these designs, Yordan. Don't worry. Maybe we'll even actually launch something.

[Harry R Ray]

Lets not get TOO excited here. This detection is at the ABSOLUTE LIMIT of the detector's sensitivity. I,for one, would like to see a transit, but there is a less than 10% probability of one. The Spitzer Space Telescope COULD(remember UCF1.01) detect a transit at the 3SIGMA level of confidence. That would convince me. If this does not happen, we may have to wait until 2020 for confirmation, when the "ESPRESSO' RADIAL VELOCITY detector has enough data to make a confirmation. NOW THE REALLY EXCITING NEWS! Another group has been focusing on this star for several years, and if I interprit their most recent blog correctly(go to www.oklo.org)they have COMBINED their data with the HARPS data, and there appears to be (to paraphrase President Obama)SKETCHY evidence for a 4.6 earth mass planet with a 250 day period, putting it near the outer edge of the habitable zone. Only time will tell.

[Sven Veneberg]

This is indeed VERY close and thus in the furnace zone. But let's not forget two things:
-The fact that it's this close means it's probably tidally locked. Hey! That means only half the planet is being toasted!
-There are two stars (technically three), which means the non-toasted half could be having a very normal day/night cicle. This planet isn't neccesarily unhabitable.

Of course, we don't know a thing about the atmosphere or anything and we can't draw a conclusion yet, but this planet may just be habitable! Don't give up your hopes yet!

[Levi Anderson]

First they find a planet orbiting around one of the best known and closest of stars, and then they discover its has near earth mass? This is incredible. what are the odds of finding something like this?

Now that we've taken the first steps into finding exoplanets wit our earths mass, its only a matter of time before we find a 2nd earth....

[Cliff]

magnificent photos "for life as we know it." Well, some LIKE it HOT!

[Joaquim Fernandes]

An humble note: two portuguese researchers in this "dream team" among the stars. The new Space Age of Discoveries count again with us - Portugal - six Centuries after the "other lands" discoveries on Earth...

[Weknownothing]

Am I correct to assume that a dual star system will have dual Goldilocks zones? Or maybe one that is larger than normal?

[Relentless]

The Na'vi? You mean the rip-off humanoids? Seriously, anything extraterrestrial in sci-fi that even remotely resembles a human can never be anything more than absolute fantasy. The insane chances of something from out-of-this world looking anything like us are just too overwhelmingly against it, and by all means... practically zero.

Plus, even if the master engineers worked up some elaborate colony ship to go to Alpha Centauri in the next several centuries (assuming we find something in the habitable zone or worth colonizing for that matter), it would still take 44 years to get there at 10% the speed of light and 22 at 20%, anything faster than that... eh, best to not count on it too much.