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Post by jandl100 on Dec 20, 2019 18:27:32 GMT
Super Puffs or Cotton candy planets - a class of very low density exoplanet. These are Jupiter sized but only have 1% of Jupiter's mass. About the same average density as candyfloss. Three have been found in a single planetary system 2,600 light years away. There's nothing at all like that in our solar system. www.sci-news.com/astronomy/kepler-51-super-puff-exoplanets-07936.htmlTwo of the planets are shedding gas at a rapid pace. ...if that trend continued, the planets could shrink considerably over the next billion years, losing their puffiness. In the end, they might wind up looking more like a common class of exoplanets called ‘mini-Neptunes.’" “The low densities of these planets are in part a consequence of the young age of the system, a mere 500 million years old, compared to our 4.6-billion-year-old Sun.” |
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Post by MartinT on Dec 20, 2019 20:52:39 GMT
Before I read your last sentence I was thinking 'young planets'.
If they shed that much gas, they will never become very dense, just smaller.
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Post by jandl100 on Jan 15, 2020 21:49:28 GMT
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Post by MartinT on Jan 16, 2020 7:17:59 GMT
It's beginning to look like planets around stars are quite common.
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Post by jandl100 on Jan 16, 2020 7:35:49 GMT
Definitely. Stars without planets would seem to be unusual..
Planets seem to be a natural byproduct of star formation.
It may well be that most planets are ejected from their solar systems due to chaotic gravitational interactions, leaving just a few that can then form up into relatively stable orbits.
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Post by jandl100 on Jan 25, 2020 20:06:59 GMT
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Post by MartinT on Jan 25, 2020 22:46:07 GMT
I don't fancy its long term prospects, especially if it's shedding material like that.
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Post by jandl100 on Feb 16, 2020 17:46:47 GMT
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Post by MartinT on Feb 16, 2020 18:02:31 GMT
I'm surprised to read that P-type orbits are stable.
How does a T-type orbit work? Won't the planet hit the low mass star, or is it 'locked' in position with it?
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Post by jandl100 on Feb 16, 2020 18:10:05 GMT
T types are gravitationally locked into place - at Lagrange points - there are the Trojan asteroids that share the orbit of Jupiter in our solar system in the same way. en.wikipedia.org/wiki/Jupiter_trojanAny orbiting mass has Lagrange points at +/- 60 degrees where smaller masses tend to accumulate. |
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Post by MartinT on Feb 16, 2020 18:21:00 GMT
Got it, thanks. I always think of binary stars as orbiting each other, but of course a much smaller star would be on the scale of Jupiter which has a small influence only over The Sun. I can picture planets at Lagrange points. What a strange view of their smaller star inhabitants would have, always in the same position in the sky. Not that it would be survivable, I expect.
EDIT: of course, the 'dark side' could be inhabitable, if its spin was locked to the main star.
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Post by jandl100 on Mar 11, 2020 17:01:26 GMT
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Post by Slinger on Mar 11, 2020 17:26:55 GMT
And people from Newcastle would STILL be walking around wearing just shorts and a pair of flip-flops.
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Post by jandl100 on Apr 3, 2020 20:39:14 GMT
astronomers have announced what may very well be a second planet orbiting the closest star to us, Proxima Centauri, probably an ice giant similar to Neptune and Uranus. The first planet detected is a little larger than Earth, and lies within the 'habitable zone' where liquid water could exist on its surface. For the second planet, measurements are borderline detectable, but probably correct. www.syfy.com/syfywire/a-second-possible-planet-for-proxima-centauri |
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Post by user211 on Apr 4, 2020 18:37:19 GMT
If you want habitable planets with alien civilisations on them, we're generally reckoned to be in the wrong place in the galaxy.
Why? The star density is far too sparse out here.
In the centre of the galaxy we wouldn't be 4 odd friggin' light years away from the nearest star. We'd be much closer. These civilisations have far more chance of spreading over solar systems than we do. There could be some pretty major stuff going on there.
In the search for extraterrestrial intelligence, we should be looking in the centre. The general reckoning is that if we find something, it will probably be machine based. Biological civilisations probably become machine based relatively quickly, at least in astronomical time scales.
The basic problem with being organic is radiation and other reasons - space is full of inhospitable environments almost conspiring to kill us. We just ain't built to explore space.
Just food for thought;)
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Post by MartinT on Apr 4, 2020 19:27:34 GMT
The problem with the inner galaxy star density could be much greater danger of cataclysmic events such as collisions, stopping life from evolving before it gets a hold.
I'm far happier being where we are, with just the odd asteroid to worry about. I agree, though, that visiting even the closest star to us is beyond any technology we could summon up right now.
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Post by jandl100 on Apr 4, 2020 19:51:26 GMT
... and the trouble with trying to listen in on alien civilisations (e.g. SETI) is that they are likely to be very far ahead of us, so we would need an understanding of their very advanced technology and its underlying physical concepts even to be able to receive and/or recognise a signal. A bit of a non-starter, really.
... e.g. how would someone from the 17th century be able to detect modern day radio communication? No chance. They wouldn't even know it was there.
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Post by user211 on Apr 5, 2020 13:49:14 GMT
The problem with the inner galaxy star density could be much greater danger of cataclysmic events such as collisions, stopping life from evolving before it gets a hold. I'm far happier being where we are, with just the odd asteroid to worry about. I agree, though, that visiting even the closest star to us is beyond any technology we could summon up right now. If interested watch this: |
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Post by jandl100 on Apr 5, 2020 21:22:56 GMT
well that was a waste of 20 minutes!  |
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Post by user211 on Apr 5, 2020 23:18:31 GMT
You should have hit the dislike button.
Oh dammit there isn't one!
I thought the first 10 minutes was OK.
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