An exoplanet with a minimum mass of 8.47±0.47 Earth masses has been discovered around 40 Eridani A:
"Star Trek's" planet Vulcan, ancestral home of Spock and his species, just became a little more real, thanks to a team of exoplanet scientists. Because "Star Trek" creators eventually associated planet Vulcan with a real star, called 40 Eridani A, scientists have wondered for years whether a factual equivalent of the beloved science fiction planet exists, with or without pointy-eared inhabitants. And now, a team of scientists has said that the star really does host at least one planet.
"This star can be seen with the naked eye, unlike the host stars of most of the known planets discovered to date," Bo Ma, lead author of the new research and an astronomer at the University of Florida, said in a statement. "Now, anyone can see 40 Eridani A on a clear night and be proud to point out Spock's home." That star, located about 16 light-years away from Earth, is also known as HD 26965. It's a bit orange, because it's a little smaller and cooler than our sun. But it also has some clear similarities to Earth's star: It's about the same age and sports a fairly similar sunspot pattern.
Also at Science Magazine.
(Score: 2) by HiThere on Wednesday September 19 2018, @05:19PM (2 children)
At 8 times Earth's mass, it's probably a hot Neptune. Well, it's actually even heavier than Neptune, but since it's closer to the sun this might be necessary to hold onto Hydrogen...I'm not sure how hot it would be in a close orbit (shorter orbit than Mercury, which has an 88 day orbit), but it likely means there's no habitable planet in that system.
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(Score: 2) by takyon on Wednesday September 19 2018, @05:45PM (1 child)
What is that supposed to mean? It is less massive than Neptune, and we don't know about the density since the radius is unknown. It could have a low density from being a puffed-up gas dwarf, or a high density for being a former gas giant with the gas blown away.
Nobody has ruled out additional planets around this star, with greater orbital periods.
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(Score: 2) by HiThere on Wednesday September 19 2018, @11:02PM
OK, you're right. That's about half Neptune's mass. I must have mis-read a Google search. That still puts it more at the gas giant size than the rocky size...though it's smaller than anything in this system. Perhaps it's hot enough to have lost most of its Hydrogen, though, so I guess it could be a bit rocky. Of course, the current theory says that the larger planets for far out and then migrate inwards, destabilizing the orbits of all the smaller planets as they come in. I don't know how certain that theory is, however, even for the local system, but if it applies to this planet's system, there won't be any habitable planets. OTOH, the resonances from this planet should be a lot weaker than those of Jupiter, so...
But at 8 Earth masses, it's not going to have a chemistry similar to one we know. I suspect it would retain Hydrogen released by splitting long enough for it to recombine, even near to top of the atmosphere. This despite the higher temperature. So the chemistry would probably be a lot more similar to that of Neptune despite the higher temperature.
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