Tag Archives: exoplanet

Captain. We’ve found an M-Class Planet

The star that is nearest our own has a planet that could be habitable by Earthlings.

This is very important news.

The news comes to us from this research paper in Nature: A terrestrial planet candidate in a temperate orbit around Proxima Centauri by Guillem Anglada-Escudé, Pedro J. Amado, John Barnes, Zaira M. Berdiñas, R. Paul Butler, Gavin A. L. Coleman, Ignacio de la Cueva, Stefan Dreizler, Michael Endl, Benjamin Giesers, Sandra V. Jeffers, James S. Jenkins, Hugh R. A. Jones, Marcin Kiraga, Martin Kürster, Mar?a J. López-González, Christopher J. Marvin, Nicolás Morales, Julien Morin, Richard P. Nelson, José L. Ortiz, Aviv Ofir, Sijme-Jan Paardekooper, Ansgar Reiners, Eloy Rodríguez, Cristina Rodr?guez-López, Luis F. Sarmiento, John P. Strachan, Yiannis Tsapras, Mikko Tuomi & Mathias Zechmeister.


At a distance of 1.295 parsecs, the red dwarf Proxima Centauri (? Centauri C, GL 551, HIP 70890 or simply Proxima) is the Sun’s closest stellar neighbour and one of the best-studied low-mass stars. It has an effective temperature of only around 3,050 kelvin, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun and a mass of about 12 per cent of the mass of the Sun. Although Proxima is considered a moderately active star, its rotation period is about 83 days and its quiescent activity levels and X-ray luminosity are comparable to those of the Sun. Here we report observations that reveal the presence of a small planet with a minimum mass of about 1.3 Earth masses orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 astronomical units. Its equilibrium temperature is within the range where water could be liquid on its surface.

Here’s why this is important. We knew that some stars that are like ours had Earth-like planets. How did we know that? Because we live on one. But how many Sun-like stars have Earth-like planets?

Trivially, we knew that all the known Sun-like stars had Earth-like planets. But that was with a sample size of one. We needed a larger sample size to estimate the actual percentage of Sun-like stars that had Earth-like planets.

Given that, consider the following question. We have a second Sun-like star. If it has no Earth-like planets, what do you think of the overall proportion of stars that have such planets? Perhaps you would guess 50-50, but the sample size is too small. Safer to simply guess, “maybe not many, because the first time we got to increment our sample size, we got nada.” Now, if it does have an Earth-like planet, what do you think of the overall proportion of stars that have such planets? Perhaps you would guess 100%, but again, the sample size is too small. But, you would safely say something like, “Well, hell, maybe a lot of them, because of the two where we have enough information to say … both have them!”

There really is no reasonable statistical way to treat this problem, but this sort of seat of the pants conjecture isn’t bad for now. But, if we were to have, say, five or six Sun-like stars to look at, we could start making real guesses.

There is a second reason. Now that we have an Earth like planet in our sights, perhaps there will be impetus for both funding and effort to squint really really hard at it and see if any life is there. Using fancy science, not actual squinting, of course.

Let us be clear. This planet is not Earth-like in that it has an atmosphere, water, or any sign of life. The planet might be locked in its orbit around its star in such a way that one side always faces that star. That would be bad for an atmosphere and for life. We don’t know if it has an atmosphere, or water. What we do know is that if water is on the surface, it might be liquid, and if an atmosphere ever formed there, maybe (though this is highly debatable) it did not necessarily get blown away into space or otherwise destroyed.

Nature made a video about the discovery:

For more information, check out these posts:

Phil Plait: Astronomers Discover a New Planet Orbiting the Closest Star to the Sun!

Mike Wall: Found! Potentially Earth-Like Planet at Proxima Centauri Is Closest Ever

Nature Podcast, an interview with the chief author:

Really scary thing seen in space

This is like an episode of Dr. Who. A star erupted and vaporized the atmosphere of a nearby planet. Holy crap. Details:

JUNE 28, 2012: An international team of astronomers using data from the NASA’s Hubble Space Telescope has made an unparalleled observation, detecting significant changes in the atmosphere of a planet located beyond the solar system. The scientists conclude that the atmospheric variations occurred in response to a powerful eruption on the planet’s host star, an event observed by NASA’s Swift satellite. This artist’s rendering illustrates the evaporation of exoplanet HD 189733b’s atmosphere in response to the powerful eruption from its host star on Sept. 7, 2011. Hubble detected the escaping gases, and Swift caught the stellar flare.


photo of outer space by write_adam

SETI will listen to newly discovered “Earthlike Planet”

First, I should say right away that the planet that has been in the news so much lately is not known to be “earth like” … depending on what you think “earth like” is. What we know is that the planet orbits its star in a position that allows for the possibility that water on its surface could be liquid. But, the possibility that the planet has a “surface” … as opposed to some increasingly dense gaseous layer like Neptune … has not yet been established. Not that this would favor life one way or another. For all we know, getting life started on a hard crust covered earth is way harder than on a gaseous liquid water rich blob of a planet.

Either way, it is very interesting that, according to reports, the US Air Force is paying SETI to restart its operations and focus on this new planet to see if we can pick anything up.

Which makes a remarkable amount of sense, don’t you think? If there’s liquid water, there’s probably life. If there is life, there is probably Milton Berle.

Source and more info