The large temperature gradient from day to night a tidally locked planet sucks the atmosphere (with supersonic winds) to the cold side of the planet. This proves problematic for habitability.
With a planet only 0.05AU away (1/20th the distance of Earth), these flares would have the potential to do damage to any organic molecules on the surface. The paper itself suggests the sterilising X-ray flux could be 400 times that experienced by Earth and are likely to have been much higher in the past.Īnother problem is that any body that close to another, larger body is likely to be tidally locked. These are so numerous and so strong that they are clearly seen four times in the ~80 nights of photometry. I know that flies in the face of every news headline, but hear me out. Firstly, as I’ve said before, Proxima Centauri throws out an abundance of flares. So do not be surprised if it turns out to be larger than this first measurement M-dwarfs and habitability:Īnother caveat is that the planet probably isn’t habitable. That is because the signal from a small planet with its orbit observed edge-on has the same signal as a larger planet observed more obliquely (pole-on). What this means is that, it could not be less than 1.3Me, but it certainly could be more. Caveats:įirstly, we only have a minimum mass for the planet. So, I have to say it: it seems unlikely that the strong signal comes from the star itself, and much more likely that we are indeed seeing the gravitational tug of an orbiting planet. And that this signal is completely different to that from the planet. And what the team see is that the photometry (the trends in brightness) matches up perfectly with the activity that is suggested by certain features in the spectra. This photometry also gives a view of the activity of the star, but without any of the doppler signal from the planet. That means not just observing the star with a spectrograph, but also simultaneously measuring its brightness with an imaging telescope. One way they have done this is with simultaneous photometry. All of these cause confusion in the radial velocities, and there have been a few planets (some of which were discovered by this very team) which are now assumed to be simply variability.īut, they have convinced me.
That manifests itself in large star-spots, strong stellar flares and varying shapes in the spectral lines (the bar-code like lines we observe in the colours of the star). One of the reasons being that Proxima is not a quiet sun-like star. When the rumours were flying, I urged caution on this potential discovery. And they found the same signal, hidden just below detectability in the past data too. And it had a 99.9999% chance of being real. They found a 1.5m/s (that’s brisk walking pace) with an 11.2 day signal. And, as we found out yesterday, that kitchen-sink technique paid off. Using the HARPS instrument on La Silla (which I am currently sat only 50m from), they took observations nearly every night for 3 months. That’s when the Pale Red Dot team decided to throw everything they could at the star to try to do what others had not. These usually involve monitoring the star’s radial velocity, it’s to-and-fro speed, and searching for the tell-tale tug of a gravitationally bound exoplanet. Many people have hunted for planets around Proxima before. Although that may sound bizarre, M-dwarfs like it are the most common type of star in our galaxy. Only 12% of the size of the Sun, it is also 100 million times fainter. The reason for it’s lackluster brightness is that the star itself is dimunative. Located only 4 lightyears away in the Alpha Centauri system, it is a tiny red speck of light, only visible in a telescope. But should we believe it? And is it all that it is hyped up to be? The star :Īs you can probably tell from the name, Proxima is the closest star to Earth. It proves what Kepler showed: Earth-like planets really are everywhere, including around the star next door. A terrestrial planet around the closest star to our sun. And it, honestly, is a breathtaking discovery. After a week of controversy and embargo-breaking, the actual science behind the detection of Proxima Centauri b is finally here (published in Nature).
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