Hello everyone,
I was surprised to discover that I could get the full text of the article about the discovery through work. It’s watermarked with the name of my employer, so I’m not even slightly tempted to “break the paywall” and post it. For anyone who has the right subscription (or can afford the outrageous one-off charge), the reference is:
Bo Ma et al.: The first super-Earth detection from the high cadence and high radial velocity precision Dharma Planet Survey. MNRAS 480, 2411–2422 (2018)
The parameters measured in the article are mass: 8.47 times the mass of the Earth, plus or minus 0.47 (so 8 to 8.94), and a period (orbit or “year”) of 42.38 days, plus or minus 0.01 days (so it’s pretty accurate) and an eccentricity of 0.04 (the eccentricity of the earth’s orbit is 0.0167, so it’s a little more, but not enough to create extreme variations of temperature on the planet).
Moving beyond that involves guesswork, and I admit that my guesses aren’t based on any really detailed knowledge. If you assume that the composition of the planet is similar to Earth’s, then my best guess is that the radius of the planet will be just under twice that of the Earth, somewhere between 1.8 and 1.9. That gives a rather savagely high surface gravity of just under 2.5 times the Earth’s. In effect, everything will weigh two and a half times what it does on Earth. That is going to be tough to cope with. I think humans would need powered exoskeletons to move anything more than really short distances.
Even if you assume that there are “twin” planets of something like four-and-a-quarter times the mass of Earth in a close orbit around each other (rather like the arrangement in “Yesteryear” or “Star Trek: The Motion Picture”) then the surface gravity is still likely to be around 1.9 times the gravity on Earth.
There is also a second article, suggesting a smaller planet:
Díaz, Matías R. et al.: The Test Case of HD 26965: Difficulties Disentangling Weak Doppler Signals from Stellar Activity. AJ, 155, 126 (2018)
As the title indicates, this wasn’t specifically an attempt to identify an exoplanet, so I’m tempted to think that the 8.45 Earth mass version is possibly closer to the reality than the 6.92, plus or minus 0.79, mass suggested in the second paper.
Of course, the exciting thing about this exoplanet is that it’s real. Exactly how big it is and what the surface gravity is like are facts, and eventually we’ll find them out.
Timon
