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Science and Astronomy Questions
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| Huesudo | Date: Sunday, 31.07.2016, 10:49 | Message # 646 |
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| Quote Watsisname (  ) This is units of Earth surface gravities (9.8m/s2) per meter.
So if you were at a point where you felt 1 G from the black hole and mover one meter towards it, you would feel 2 Gs? 
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| Watsisname | Date: Sunday, 31.07.2016, 11:15 | Message # 647 |
 Galaxy Architect
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| Not exactly. The difference in the pull of gravity over that one meter is 1g. You might be falling in with an acceleration of thousands of g's. It's not the acceleration that your body feels (you don't feel freefall), but the difference. If you fall in feet-first, it feels like your feet are pulled downward and your head upward.
This is why being close to stellar-mass black holes is very bad for you. The difference in the pull of gravity over your body is huge. It easily tears you apart.
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| spacer | Date: Sunday, 31.07.2016, 11:19 | Message # 648 |
 Star Engineer
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Israel
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| Quote Watsisname ( ) This is why being close to stellar-mass black holes is very bad for you. The difference in the pull of gravity over your body is huge. It easily tears you apart
i heard that we could survive falling to super massive black hole.
i guess i know understand why 
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
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| FastFourierTransform | Date: Sunday, 31.07.2016, 16:27 | Message # 649 |
 Pioneer
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| Quote spacer ( ) i heard that we could survive falling to super massive black hole.
i guess i know understand why smile
Yes. Because tidal forces are not so great from that distance to the singularity (if you are above the event horizon of a very very massive black hole). But you would be equally disrupted after passing the horizon.
Alow me to continue with the stellar encounter issue
Quote Watsisname ( ) Alek, thanks for checking that out! It seems that an expected close encounter would have affected its orbit in a measurable way (if we could measure it), but not so much as to greatly affect the solar system's dynamics. That's pretty neat!
Yeah! that's totally awesome. If we finally discover planet 9 we could find clues of a close stellar encounter with the solar system. And maybe with the Gaia data we could find the star that once invaded our system. Maybe we exchanged material with that star (asteroids and comets) and we would know that there are captured objects of the other system in our solar system to explore to find different chemical composition.
Well, considering that the galactic year is about 250 million years (not so much) it's probable that this star could be everywhere in the galaxy, totally undetectable or not in the gaia census. So I may be so wrong about my expectations.
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| spacer | Date: Sunday, 31.07.2016, 16:33 | Message # 650 |
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Star Engineer
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Israel
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| this star could also be the reason for mass extinction events on earth.
also there is good probabilty that a planemo pass our system. and who knows?
maybe planet 9 is a planemo that cought by the sun gravity
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
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| midtskogen | Date: Sunday, 31.07.2016, 17:04 | Message # 651 |
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| Quote Watsisname ( ) Look, I get why this is so hard to swallow for most people. I really do. We're saying we are confident in the existence of invisible, mysterious entities and forces that we can't detect directly.
It's not hard to swallow that dark matter and energy exist. It's the best descriptions that we have. And it doesn't matter that it can't be detected directly. Most exoplanets can't either, but exoplanets are familiar things, the same kind of stuff that we see and touch in our own solar system, so there is no reason to think that these things are different from what they look like, no reason to suspect that we're describing shadows in Plato's cave.
NIL DIFFICILE VOLENTI
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| Watsisname | Date: Monday, 01.08.2016, 00:20 | Message # 652 |
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Galaxy Architect
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| Quote FastFourierTransform ( ) Well, considering that the galactic year is about 250 million years (not so much) it's probable that this star could be everywhere in the galaxy, totally undetectable or not in the gaia census. So I may be so wrong about my expectations.
We have the same problem with trying to identify the Sun's "sibling" stars, which formed with it out of the same molecular cloud. We can identify them by their compositions, ages, and tracing back their orbits, but over 4.5 billion years they've drifted a long way and are hard to find. We finally just found one a couple years ago, which was a nice surprise.
With stars that had very close encounters with the solar system long ago, another challenge is that the precision of measurement of their motion may be too weak to constrain the distance and geometry of the encounter, if we're dealing with only thousands of AU. I think it'd be really hard to connect a distant star to a precise change in solar system orbits, without knowing what the orbits were before the encounter.
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| Huesudo | Date: Monday, 01.08.2016, 10:48 | Message # 653 |
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Observer
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| Quote midtskogen ( ) the same kind of stuff that we see and touch in our own solar system
Our solar system has a bunch of peculiarities. The innermost planet is a stripped iron core, and the two outer gas giants are in places where planet formation shouldn't be possible.
And unlike most other solar systems discovered, ours doesn't have any hot jupiters or super earths surfing just above the star's surface.
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| midtskogen | Date: Monday, 01.08.2016, 11:18 | Message # 654 |
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Star Engineer
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| Quote Huesudo ( ) Our solar system has a bunch of peculiarities. The innermost planet is a stripped iron core, and the two outer gas giants are in places where planet formation shouldn't be possible.
Why is this peculiar?
Quote Huesudo ( ) And unlike most other solar systems discovered, ours doesn't have any hot jupiters or super earths surfing just above the star's surface.
That's because it's those kind of planets we can currently discover. You can't base ideas of typical planet distribution on that.
NIL DIFFICILE VOLENTI
Edited by midtskogen - Monday, 01.08.2016, 11:18 |
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| Watsisname | Date: Monday, 01.08.2016, 12:04 | Message # 655 |
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Galaxy Architect
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| It's also possible that systems where gas giants migrate close to the host stars are less likely to produce habitable-zone terras.
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| midtskogen | Date: Thursday, 11.08.2016, 16:54 | Message # 656 |
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Star Engineer
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Norway
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| Where are the new particles?
NIL DIFFICILE VOLENTI
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| spacer | Date: Thursday, 11.08.2016, 17:05 | Message # 657 |
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Star Engineer
Group: Users
Israel
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| need more time. if we didnt find it now, doesnt mean we wont find any forever.
there is missing piece of the pazzle, i hope we find it someday. if not today.... there is always tomorrow.
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
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| Watsisname | Date: Thursday, 11.08.2016, 20:52 | Message # 658 |
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Galaxy Architect
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| The obvious answer is that they have gone off into hiding, from the awful particle physicists who would smash them to bits. 
This looks like bad news for super-symmetry. Multiverse aficionados are probably loving it. I was reading a paper in the same vein the other day about the lack of sterile neutrinos found by IceCube, which was also a bit of a disappointment.
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| steeljaw354 | Date: Thursday, 11.08.2016, 21:07 | Message # 659 |
 World Builder
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Pirate
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| What caused Niku and Drac to have a such strange orbit?
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| Watsisname | Date: Thursday, 11.08.2016, 21:33 | Message # 660 |
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Galaxy Architect
Group: Global Moderators
United States
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| The orbit itself isn't strange. It's easy to get highly inclined or even retrograde orbits by interactions with planets.
What's strange is that there is an apparent clustering of several orbits. Six objects are known to share similar orbital planes with that high inclination, which suggests a common source and evolution. We don't know what would have caused that. The clustering should not be stable over billion year timescales because the orbits precess. It's not likely to be related to planet 9 because the distances are too large -- simulations show a planet 9 wouldn't affect them enough to keep them in the same orbital plane.
We need to find and study a lot more of these to begin to tease out their origins. We lack a lot of data on them since most surveys stick to near the ecliptic plane.
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