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Forum » SpaceEngine » Science and Astronomy Discussions » Science and Astronomy Questions
Science and Astronomy Questions
FastFourierTransformDate: Sunday, 01.02.2015, 09:50 | Message # 331
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Quote pzampella ()
Are the Magellanic Clouds really flat like in SE? Because I would expect them to be like clouds, more width.


Es cierto!, una buena pregunta. Me he puesto a buscar un poco por si encontraba algo que fuera intelegible y me he topado con esto: http://shodhganga.inflibnet.ac.in/bitstre....208.pdf

Según el artículo (que no he leido entero ni mucho menos biggrin ) parece ser que las dos nubes de magallanes son elipsoides. La medida por ejemplo de la pequeña nube de magallanes lleva a que la proyección en el plano de la visual veamos una especie de elipse donde un semieje es el doble que el otro mientras que la profundida es cuatro veces superior a el semieje pequeño mencionado. Es decir, es como una patata estirada en la dirección de la via lactea (lo contrario de lo que aparece en SE). las medidas de la SMC son 1:2:4
El artículo es largo pero seguro que encuentras información útil. Habría que cambiar el aspecto de las nuebes de magallanes en el programa, eso seguro smile
 
abyssoftDate: Sunday, 01.02.2015, 15:23 | Message # 332
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Quote Handbanana ()
Why is it impossible for high mass terrestrial planets to exist? In other words, why are the massive planets always gaseous and never have solid surfaces?


This a is a good question given that they have now discovered a exoplanet that is thought to still be a super earth / super oceana at 20 Me. From what I can tell currently if a planet has a mass >= 10 Me it automatically gets converted into a neptunian like ice giant; and the Terra, Desert, Selena, and IceWorld settings are ignored.
 
WatsisnameDate: Sunday, 01.02.2015, 21:02 | Message # 333
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It is not strictly impossible for a massive (>>10Me) terrestrial planet to form, but it's hard to imagine how it would happen with our current understanding of planet formation processes. Once planets get that massive, they are able to gather and retain gas directly from the nebular disk, so they tend to develop into ice and gas giants.

So if massive terrestrials do exist, then there may be more interesting disk dynamics involved. Somehow the disk must have regions with huge amounts of rock and heavy volatiles, but without the H and He, either because the disk formed that way or they were separated out later.





 
Stargate38Date: Monday, 02.02.2015, 00:00 | Message # 334
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PSR J1719-1438 b is 1.02 times the mass of Jupiter, yet it has a density of 23 g/cm^3 (as dense as iridium). Is it possible that it may be rocky, given such a high density, or is most of that mass in the core?
 
apenpaapDate: Monday, 02.02.2015, 00:08 | Message # 335
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It is thought to be composed of crystalline carbon at a far higher density than diamond, according to wikipedia. Apparently it is thought to be the remnant of a white dwarf that has had large parts of it stripped away by the pulsar, leaving only the core.




I occasionally stream at http://www.twitch.tv/magistermystax. Sometimes SE, sometimes other games.
 
HarbingerDawnDate: Monday, 02.02.2015, 07:05 | Message # 336
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Quote apenpaap ()
Apparently it is thought to be the remnant of a white dwarf that has had large parts of it stripped away by the pulsar, leaving only the core.

One problem with this hypothesis is that the planet is thousands of times less dense than a white dwarf.





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TemperateTerraIsBestDate: Saturday, 14.02.2015, 01:50 | Message # 337
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Please don't go off topic.

Added (14.02.2015, 00:50)
---------------------------------------------
How a neutron star is made (I think): A star with 10 times the mass of the sun goes supernova, the remaining core's electrons and proton's fuse into neutrons... biggrin :D biggrin

Mod edit: Merged post here -- I really don't think we need a new thread for this topic.
~Wats





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DodecahedronDate: Thursday, 05.03.2015, 03:04 | Message # 338
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What would be the composition of an atmosphere with an average molar mass of 39.1?




" What compromises in precision should scientists make in the name of tradition, sentiment, and good public relations?"
None
 
WatsisnameDate: Thursday, 05.03.2015, 07:24 | Message # 339
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No unique answer; it could be a number of things in various combinations. To calculate it, use the set of equations

Mav = f1G1 + f2G2 + ... + fnGn
f1 + f2 + ... + fn = 1
for f in the range [0,1]

where the G's represent the molar mass of the gases involved, and the f's represent their fractional abundance.

Obviously there must be at least one gas with a molar mass greater than the average, and at least one weighing less than the average, unless it just happens to be exactly equal to the molar mass of one particular gas. There aren't very many common atmospheric gases heavier than 39.1g/mol, but CO2 is one and it comes in at 44.01. This would be a likely component in high abundance.

Suppose we choose this atmosphere to have just two gases, CO2 and N2 (28g/mol). Then
39.1 = f1(44.01) + f2(28)
f1 + f2 = 1

Do a little linear algebra, and we get 69.3% CO2 and 30.7% N2 as a possible solution for this atmosphere's composition. Needless to say there are an infinite number of others.





 
n0b0dyDate: Thursday, 05.03.2015, 09:20 | Message # 340
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I have a question regarding black holes (which is theoritical):
What effect would a living being (a human for example) start to feel 1st as it falls into a black hole?
Lets asume that he/she is inside a spacecraft or at least a spacesuit.

I have a feeling that they should initially feel the temperature rising before the effect of gravity becomes noticeable. But I am probably wrong.

Maybe the radiation will rise 1st and they get radiation sickness, then burn because of high tempreture, then gravity but they would probably be dead long before gravity (or even temperature) rises.

Maybe the effects will vary in magnitude and order of appearance depending on the size/mass of the black jole?..

Sorry for my ignorance cry
 
apenpaapDate: Thursday, 05.03.2015, 09:47 | Message # 341
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Quote n0b0dy ()
Maybe the effects will vary in magnitude and order of appearance depending on the size/mass of the black jole?


This is my guess. I know that with supermassive black holes, like the ones in the centre of galaxies, you wouldn't feel the tidal effects until you've already passed the event horizon, while stellar mass black holes will have torn you apart by then. On the other hand, galactic black holes are more likely to have big accretion disks around them. So in general, I'm pretty sure the radiation would get you with a galactic black hole, while with a stellar one it could be either the radiation or the tidal effects, depending on whether it's got much of an accretion disk.





I occasionally stream at http://www.twitch.tv/magistermystax. Sometimes SE, sometimes other games.
 
WatsisnameDate: Thursday, 05.03.2015, 10:42 | Message # 342
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Does the black hole have an accretion disk or is it quiescent?

For a black hole that isn't eating anything and has no disk, you won't have any temperature or radiation effects. It'll be just like you're in empty space. You also won't feel the gravity, but rather the tidal forces. If you fall in feet first, this feels like your feet being pulled downward and you head upward. You will also feel compressed about your middle. The strength of these forces increases as you get closer, and they are also stronger (relative to the event horizon's size) for a smaller black hole. A stellar mass black hole would prove fatal before you reach the horizon, but for a supermassive black hole you can fall well within the horizon before even noticing them.

If there's an accretion disk, then the radiation (mostly thermal, not charged particles) from that disk is what will kill you first. The extremely high velocities of material in the disk would also prove fatal if you freely fell through it without matching speed.





 
midtskogenDate: Thursday, 05.03.2015, 13:13 | Message # 343
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If it has a proper disk, would it help to fall in towards a very high latitude?




NIL DIFFICILE VOLENTI
 
WatsisnameDate: Thursday, 05.03.2015, 16:09 | Message # 344
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That would solve the problem of being subjected to very high speed material, unless there are jets, which a robust disk will probably produce. But even without jets, the intensity of radiation from the disk would be a problem on a polar trajectory, since you're seeing it face on. Then there's the gravitational lensing which brings much of the disk into view no matter where you are, as Interstellar nicely showed.

My feeling is that as far as active black holes are concerned, you're better off staying far the heck away from them. smile





 
AlekDate: Monday, 27.04.2015, 03:06 | Message # 345
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About the black holes thing, Yes, indeed the lensing effect does come into play, but that effect is only produced because light is being bent by extremely strong gravity: before you ever would get to that point you'd either be fried or ripped to shreds by the accretion disk. And actually, a lot of times there are no jets formed from the eating of material by the black hole, so coming in at a high latitude would help if you want to be pulled into spaghetti. (hence the term "spaghettification") by the tidal forces. Now, you at first with the tidal effects would feel good actually, like you're having a good stretch, and then eventually it would start to hurt, until the pain from being pulled apart knocks you out. After that you literally will be separated head-upper torso-lower torso-feet and then those parts of your body will be pulled apart in a string...aaand then it starts getting really gory...




Living among the stars, I find my way. I grow in strength through knowledge of the space I occupy, until I become the ruler of my own interstellar empire of sorts. Though The world was made for the day, I was made for the night, and thus, the universe itself is within my destiny.
 
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