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Post by jandl100 on Jul 12, 2019 8:02:05 GMT
All the rage these days -- detecting and observing planets around other stars. Exoplanet - extrasolar planet. Our own solar system, with its central star and collection of orbiting planets and moons. Is it unique or do some of the 250 billion other stars in our galaxy also have them? And if so, how similar to our own solar system are they? And the seemingly countless stars in the countless other galaxies in the known universe? Interesting topic that has cropped up occasionally in other astronomically related threads, I thought it deserved its own thread as discoveries are occurring increasingly rapidly. And the search for 'life as we know it' elsewhere in the universe seems to be heavily dependent on the issue. It's technically a very challenging thing to do - stars themselves dominate their own locality by many orders of magnitude as far as most measurable quantities are concerned, so it's very hard to find any very much smaller orbiting exoplanets and a variety of techniques are used to do this. Anyway, here's a good intro for those interested .... en.wikipedia.org/wiki/Exoplanet"As of 1 July 2019, there are 4,096 confirmed planets in 3,053 systems, with 664 systems having more than one planet." |
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Post by jandl100 on Jul 12, 2019 8:07:30 GMT
Here's a short vid showing the rate of discovery of exoplanets and their position in our night sky.
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Post by jandl100 on Aug 2, 2019 7:35:32 GMT
Here's an interesting recent discovery. "Hot Jupiter" planets are those that are similar in nature to our own Jupiter - large gaseous - that orbit VERY closely to their parent star. The exoplanet WASP-121b has been found to orbit its star so closely that its atmospheric temperature is over 2,500 degrees Centigrade - extreme even for Hot Jupiters. It's year is about 1.3 days - it really zips around! - and is a mere 3.8 million km distant from its star (Mercury by comparison is 58 million km from our sun). In fact, WASP-121b is so close to its star that it has been distorted into the shape of a rugby ball by tidal forces. Source |
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Post by MartinT on Aug 2, 2019 9:11:43 GMT
Surely Wasp121b's orbit will decay with all that drag going on?
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Post by jandl100 on Aug 2, 2019 19:04:09 GMT
Surely Wasp121b's orbit will decay with all that drag going on? Yes, very slowly I would guess. In X million years it will probably plunge into its star. Unless the orbits get re-arranged again .... it probably ended up so close due to gravitational interactions with other planets in the system, having formed very much further out. |
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Post by jandl100 on Aug 2, 2019 19:18:49 GMT
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Post by jandl100 on Aug 12, 2019 18:17:15 GMT
"Today, astronomers have numerous extrasolar systems to study, but most look very different from our own. Determining how these solar systems — and ours — formed is challenging. New research lends credence to an idea that goes against previous thoughts about planet formation, but has been gaining traction in the field: Giant planets that orbit their stars in a matter of days may have formed in place close to their suns, rather than moving inward from much farther away." Hot Jupiters are found in about 1% of planetary systems - astonishing things, scalding hot, that orbit in a few days just a few million miles from their star. Artist's impression (way beyond the ability of current telescopes!) ...  Once you do the physics and maths it seems that they can form very close to the star, using a 'super Earth' planet as the rocky core foundation, and also survive there for the lifetime of the star (billions of years) losing only a few % of their gaseous makeup to the unimaginably fierce radiation blast. www.astronomy.com/news/2019/01/hot-jupiters-may-form-close-to-their-stars?utm_source=asyfb&utm_medium=social&utm_campaign=asyfb&fbclid=IwAR2op3Z80b14h4s4zwaw8ZOZazFepZzboZ5KUjInPcCiEalwNtF2a5vaTGE |
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Post by MartinT on Aug 12, 2019 20:14:45 GMT
the unimaginably fierce radiation blast. That would be a challenge to life. Never say never, though. |
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Post by jandl100 on Aug 12, 2019 20:18:59 GMT
True.
Hot Jupiters tend to be tidally locked, always presenting the same side to the star, so conditions will be less extreme on the 'dark side' although still likely to be unimaginably violent by our standards.
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Post by jandl100 on Aug 20, 2019 6:00:55 GMT
Earth sized exoplanet directly observed with an infrared telescope. "The planet makes one full revolution around its parent star in just 11 hours. With such a tight orbit, LHS 3844b is most likely "tidally locked," which is when one side of a planet permanently faces the star. The star-facing side, or dayside, is about 1,410 degrees Fahrenheit (770 degrees Celsius). By measuring the temperature difference between the planet's hot and cold sides, the team found that there is a negligible amount of heat being transferred between the two. If an atmosphere were present, hot air on the dayside would naturally expand, generating winds that would transfer heat around the planet. "The temperature contrast on this planet is about as big as it can possibly be," said Laura Kreidberg, a researcher at the Harvard and Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and lead author of the new study. "That matches beautifully with our model of a bare rock with no atmosphere." " www.jpl.nasa.gov/news/news.php?feature=7479&utm_source=iContact&utm_medium=email&utm_campaign=nasajpl&utm_content=daily-20190819-2 |
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Post by jandl100 on Aug 29, 2019 8:15:58 GMT
(Another) unusual exoplanet discovered. HR 5183b. This one is 3 times the mass of Jupiter and in a very elliptical orbit around its star,. There is a good graphic in this link showing how its orbit compares to planets in our own solar system. It seems likely that this giant planet had a close encounter with another massive planet, with the other one being ejected from the solar system entirely and this planet being left in a very eccentric (non-circular) elliptical orbit. The planet was discovered spectroscopically, by observing the way the central star jigs around as the planet orbits it. Star and planet orbit around their common centre of gravity. astronomynow.com/2019/08/28/exoplanet-found-in-unusually-long-elliptical-orbit/ |
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Post by jandl100 on Aug 29, 2019 16:44:28 GMT
Just out of curiosity - is anyone interested in this stuff? If not, I'll stop wasting my time posting!  |
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Post by MartinT on Aug 29, 2019 16:50:12 GMT
Yes!!
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Post by jandl100 on Aug 30, 2019 6:39:58 GMT
Hmm, just the one, then! An important 'one', of course! |
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Post by John on Aug 30, 2019 6:53:12 GMT
I am also
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Post by Firebottle on Aug 30, 2019 7:17:35 GMT
Me too Jerry, always had an interest in astronomy.
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Post by MartinT on Aug 30, 2019 7:27:44 GMT
Do keep it going please, Jerry. I don't always look for astronomy stories and you have sources I don't use. Your posts are always interesting.
That orbit is quite bizarre and, as you say, must have come about due to a 'coming together' at some point in its history.
I can imagine what such an orbit would do to our planet: ice seasons followed by fearsome heat if there was spin and angle.
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Post by jandl100 on Aug 30, 2019 7:40:19 GMT
OK  -- a 'thumbs up' on a post will show that it's been of interest.  |
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Post by Pinch on Aug 30, 2019 8:24:01 GMT
More please!
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Post by jandl100 on Sept 12, 2019 10:31:04 GMT
Interesting recently announced exoplanet with water vapour in its atmosphere. It's in the current news quite a bit. www.sciencenews.org/article/first-known-exoplanet-rain-clouds-water-droplets?utm_source=email&utm_medium=email&utm_campaign=latest-newsletter-v2&utm_source=Latest_Headlines&utm_medium=email&utm_campaign=Latest_HeadlinesIt's orbit around its star is in the 'habitable zone' where liquid water could exist on its surface. So quite a lot of excitement about that. It's about 8x the mass of the Earth and 2.5 times its diameter, what is known as a "Super Earth". So any higher lifeforms that evolved there would likely be very robust and muscle-bound due to the high gravity. Still, it's the first detection of water vapour and likely rain on an exoplanet that could maybe support life. A recent theory suggests that many Super Earths will be waterworlds, with planet-wide oceans 100s or 1000s of miles deep. The water there could constitute up to 50% of the planet's mass, compared with 0.02% on Earth. In which case any life would be aquatic. This wet exoplanet is 111 light years away, so it's close by astronomical standards, and circling a dim red dwarf star, much smaller and dimmer than our sun and likely prone to massive surface eruptions which could give the orbiting planet(s) a hard time. |
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