Astronomers discover super-Earth around Barnard's star

November 14, 2018, Queen Mary, University of London
Artist's impression of the surface of Barnard's star b. Credit ESO-M. Kornmesser. Credit: Credit ESO-M. Kornmesser

Astronomers have discovered a planet in orbit around one of the closest stars to the Sun, Barnard's star.

The study was co-led by researchers from Queen Mary University of London, and from the Institut d'Estudis Espacials de Catalunya and the Institute of Space Sciences/CSIC in Spain.

The potentially rocky planet, known as Barnard's star b, is a 'super-Earth' with a mass of at least 3.2 times that of the Earth, and it orbits around its host star once every 233 days.

The results, published in the journal Nature, show the planet lies at a distant region from the star known as the 'snow line'. This is well beyond the habitable zone in which liquid water, and possibly life, could exist.

The planet's surface temperature is estimated to be around -170 degrees Celsius meaning it is likely to be a frozen world which is uninviting to Earth-like life.

However, if the planet has a substantial atmosphere the temperature could be higher and conditions potentially more hospitable.

Dr. Guillem Anglada Escudé, from Queen Mary's School of Physics and Astronomy, said: "Barnard's star is an infamous object among astronomers and exoplanet scientists, as it was one of the first stars where planets were initially claimed but later proven to be incorrect. Hopefully we got it right this time."

Artist’s impression of Barnard’s Star planet under the orange tinted light from the star. Credit: IEEC/Science-Wave - Guillem Ramisa

At nearly six light-years away Barnard's star is the next closest star to the Sun after the Alpha Centauri triple system.

It is a type of faint, low-mass star called a red dwarf. Red dwarfs are considered to be the best places to look for exoplanet candidates, which are planets outside our solar system.

Barnard's star b is the second closest known exoplanet to our Sun. The closest lies just over four light-years from Earth and was also discovered by a team led by Queen Mary's Dr. Anglada Escudé in 2016. That exoplanet, called Proxima b, orbits around the red dwarf star Proxima Centauri.

The researchers used the radial velocity method during the observations that led to the discovery of Barnard's star b. This technique detects wobbles in a star which are likely to be caused by the gravitational pull of an orbiting planet.

These wobbles affect the light coming from the star. As the star moves towards the Earth its spectrum appears slightly shifted towards the blue and, as it moves away, it is shifted towards the red.

This is the first time that this technique has been used to detect a planet this small so far away from its .

The researchers re-examined archive data obtained over a 20-year period, and added new observations with the latest generation of instruments, namely the CARMENES spectrometer in Spain, the ESO/HARPS instrument in Chile and the HARPS-N instrument in the Canary Islands.

Graphic representation of the relative distances to the nearest stars from the Sun. Barnard’s star is the second closest star system, and the nearest single star to us. Credit: IEEC/Science-Wave - Guillem Ramisa

This wealth of data provided the extraordinary accuracy needed to identify the influence of the planet with near certainty. The wobble observed in the star's motion corresponds to speeds of only just over 1 metre per second—about walking speed.

Dr. Ignasi Ribas, from Institut d'Estudis Espacials de Catalunya and the Institute of Space Sciences in Spain, said: "After a very careful analysis, we are over 99 per cent confident that the planet is there, since this is the model that best fits our observations. However, we must remain cautious and collect more data to nail the case in the future."

Further observations to increase the confidence of this result are already under way at various observatories, and the system is an excellent candidate for observation by the next generation of instruments specifically designed to image exoplanets directly, such as NASA's planned Wide Field Infra Red Survey Telescope (WFIRST).

If the planet can be observed directly it will provide vital information about its properties and extend our understanding of the kinds of that form around red dwarf .

An award-winning public engagement campaign, known as Pale Red Dot, allowed the public to follow in real time the observations and analysis that led to the discovery of Proxima b.

The public have also been able to follow the observations leading to this new discovery, a result of extending the search to other very nearby , via a similar web-based campaign known as the Red Dots project, @reddotsspace on Twitter).

The study includes contributions from Professor Richard Nelson and research student John Strachan, both members of Queen Mary's School of Physics and Astronomy.

This research was supported in part by the UK Science and Technology Facilities Council and a Queen Mary University of London Principal's Postgraduate Studentship.

Explore further: Assist astronomers' new hunt for Earth-like planets

More information: I. Ribas et al. A candidate super-Earth planet orbiting near the snow line of Barnard's star, Nature (2018). DOI: 10.1038/s41586-018-0677-y

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25 comments

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Nik_2213
5 / 5 (5) Nov 14, 2018
Sadly, Peter van de Kamp, of Barnard's Star etc false-positives, has not lived to see this...
Da Schneib
4.6 / 5 (10) Nov 14, 2018
Interesting. Barnard's Star is close, as such things go. Obviously we'll look at Proxima b first, but this is another one in our near neighborhood (again, as such things go).
Muphet
5 / 5 (4) Nov 15, 2018
"However, if the planet has a substantial atmosphere the temperature could be higher and conditions potentially more hospitable."

-can be applied to every single planet ever. cool story
JongDan
5 / 5 (5) Nov 15, 2018
Is it confirmed a super-earth? With M sin(i) = 3.23 M⊕, a mini-neptune shouldn't be excluded either.
Nik_2213
5 / 5 (5) Nov 15, 2018
Would this 'triple earth' or 'mini-neptune' be big enough to tidally stir and thaw an inner ice-moon ?
Ajhsys
5 / 5 (2) Nov 15, 2018
It seems to me that at 3X the mass of Earth, you would weigh 3 times as much as on Earth. I doubt I could function at 600 lbs.
Spacebaby2001
3.7 / 5 (3) Nov 15, 2018
It seems to me that at 3X the mass of Earth, you would weigh 3 times as much as on Earth. I doubt I could function at 600 lbs.


I donno given the pop definition of function, and a good quality welfare state, you could probably do quite well.
Da Schneib
5 / 5 (7) Nov 15, 2018
It seems to me that at 3X the mass of Earth, you would weigh 3 times as much as on Earth. I doubt I could function at 600 lbs.
That depends on its diameter. Remember the r² in the denominator.
jonesdave
4.6 / 5 (10) Nov 15, 2018
It seems to me that at 3X the mass of Earth, you would weigh 3 times as much as on Earth. I doubt I could function at 600 lbs.
That depends on its diameter. Remember the r² in the denominator.


By my very rough approximations and calculations, I come up with ~ 1.4 x Earth gravity. The assumption here is that we assume the planet is roughly the same composition and density as Earth. Therefore the cube root of 3.2 Earth masses, = ~ 1.5 Earth radii. 3.2/ 1.5^2 = ~ 1.4. This is the minimum, as 3.2 is a minimum estimate. So an 80 kg person would weigh ~112 kg. Not so bad.
rrwillsj
5 / 5 (2) Nov 15, 2018
The first question I have, Is the super-earth tidally locked?

Second, what are the rates of major flares from the star?

Third, since the luminosity from Barnard's Star is so low? Magnitudes less than Sol.
Is photosynthesis even possible?
If not, any minuscule probability for biology would be anaerobic?
Da Schneib
4.2 / 5 (5) Nov 15, 2018
It seems to me that at 3X the mass of Earth, you would weigh 3 times as much as on Earth. I doubt I could function at 600 lbs.
That depends on its diameter. Remember the r² in the denominator.


By my very rough approximations and calculations, I come up with ~ 1.4 x Earth gravity.
I got √3. Say 1.7. :D
Da Schneib
4.2 / 5 (5) Nov 15, 2018
The first question I have, Is the super-earth tidally locked?
Got a ten-mile-wide telescope to use to find out?

Don't want much do you?
jonesdave
3.4 / 5 (5) Nov 15, 2018
It seems to me that at 3X the mass of Earth, you would weigh 3 times as much as on Earth. I doubt I could function at 600 lbs.
That depends on its diameter. Remember the r² in the denominator.


By my very rough approximations and calculations, I come up with ~ 1.4 x Earth gravity.
I got �š3. Say 1.7. :D


Now you've confused me (and I'm only on my first pint!) Why sqrt 3?
Da Schneib
4 / 5 (4) Nov 15, 2018
Size and mass. Must be late where you are!
jonesdave
3.9 / 5 (7) Nov 15, 2018
The first question I have, Is the super-earth tidally locked?


I had a quick read of the paper earlier. From memory the planet is at 0.4 AU, which is the snow line in this system. This is somewhat further than Mercury in our system. The star is much less massive than ours, and the planet is far more massive than Mercury. Short answer? Haven't got a clue :)
jonesdave
3.7 / 5 (6) Nov 15, 2018
Size and mass. Must be late where you are!


Hmmmm, maybe we are at cross purposes. I went with 3.2 M earth. Given that we are dealing with a 3d object, I simplified and assumed 3.2 Earth volumes. Given the volume of a sphere involves r^3, then to get the radius I took the cube root of 3.2 = ~ 1.5. To calculate the gravity, I just put M (3.2)/ r^2 (1.5^2), = ~ 1.4.
Spacebaby2001
5 / 5 (3) Nov 15, 2018
I don't believe in jinxes, so eff it. What a effing nice converstaion. Cheers
rrwillsj
5 / 5 (4) Nov 15, 2018
"... Got a ten-mile-wide telescope to use to find out?

Don't want much do you? ..."

Yes DS. Yes I do! And what you & jd have incentive me too? Is go go draw my own damn pint!

If I wasn't such a lazy ass. I could look up those telescopes where the apertures? are separated by distance? What distance and what size of the telescopes to be equivalent to a lens ten miles across?
AllStBob
5 / 5 (4) Nov 16, 2018
It seems to me that at 3X the mass of Earth, you would weigh 3 times as much as on Earth. I doubt I could function at 600 lbs.

Assuming it was the same density as the Earth acceleration due to gravity at its surface would be 1.44 times that on Earth (=3^(1/3))
Da Schneib
4 / 5 (4) Nov 16, 2018
Ha! I should have known to take the cube root! @Bob wins the internets for tonight!
torbjorn_b_g_larsson
4.2 / 5 (5) Nov 16, 2018
Unless it's a neptune (seems Hubble can exclude that), a dense atmosphere and tidal heating et cetera can make it surface habitable; if not, ice world habitable; or if neptune could have a smaller moon with all that.

The first question I have, Is the super-earth tidally locked?


I hear equivalent distance to Mercury, which is not; even if it would be closer many could-be-locked are not in models.

Second, what are the rates of major flares from the star?


High IIRC; but again a dense atmosphere or water/ice world would not care.

Third, since the luminosity from Barnard's Star is so low? Magnitudes less than Sol.
Is photosynthesis even possible?


Photosynthesis is done in the IR glow from hot, acidic vents (> 100 degC). Not oxygenating such of course, don't work on IR.

If not, any minuscule probability for biology would be anaerobic?


Oxygenating PS is difficult and relatively late here, do not expect it to be common.
Mark Thomas
3.7 / 5 (3) Nov 16, 2018
Got a ten-mile-wide telescope to use to find out?


No, but in theory we could build a space-based interferometer with an effective aperture that large. The cancelled Terrestrial Planet Finder was supposed to have an effective aperture baseline much smaller than that at 40-100 meters, but still a good start.

http://www.citize...elescope

Suffering from a clear and lamentable lack of warp drive, increasingly sophisticated telescopes seem to be in our future for a long time to come.
Mark Thomas
3.7 / 5 (3) Nov 16, 2018
This discovery is yet another piece of evidence suggesting that most or even all the stars around us have planets too. If that is true, then it seems likely Alpha Centauri A and B have planets. Since those have not been discovered, perhaps that is because they are closer to being Earth-sized or even Mars-sized planets. I recall reading Jupiter-sized planets have been ruled out there. Terrestrial planets in the habitable zones would be compelling.

Probably long before we are ready to send an interstellar probe, we will know the primary target of that probe. If it is not Proxima b, one might hope there is something compelling in the Alpha Centauri A-B system that motivates us to boldly go where no one has gone before.
Mark Thomas
3.7 / 5 (3) Nov 16, 2018
Second, what are the rates of major flares from the star?


I found it interesting that Barnard's Star is estimated to be 10 billion years old. Older stars like Barnard's stars are thought to have much less flares, but it still had a detectable flare in 1998, so nothing is certain.

https://en.wikipe...27s_Star

The fact that this newly discovered planet is also probably 10 billion years old is more than a little interesting.
TrollBane
4.3 / 5 (3) Nov 17, 2018
Alas, no Gargantua or Rocheworld. Yet there remains some room for a world in a closer, warmer orbit of a lesser mass that isn't yet detectable by the radial velocity method.

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