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Topic: Kepler-16b, also known as...Tatooine! (Read 2389 times)
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Lucas
Terracotta Army
Posts: 3298
Further proof that Italians have suspect taste in games.
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" He's so impatient, it's like watching a teenager fuck a glorious older woman." - Ironwood on J.J. Abrams
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01101010
Terracotta Army
Posts: 12007
You call it an accident. I call it justice.
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I read this today and my immediate thought was: how do they actually know all this. Then I woke up in a puddle of drool knowing that I can never be able to wrap my head around it. |
Does any one know where the love of God goes...When the waves turn the minutes to hours? -G. Lightfoot
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Merusk
Terracotta Army
Posts: 27449
Badge Whore
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Ha, take that scientists who used to laugh because 'that planet is impossible!"  |
The past cannot be changed. The future is yet within your power.
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pxib
Terracotta Army
Posts: 4701
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I read this today and my immediate thought was: how do they actually know all this.
Light and gravity. We can cheat with stars since we can discern their temperature based on which spectral lines they display, and from their temperature and composition we can pretty precisely determine their mass and diameter. As a large diameter planet crosses between the star it orbits and us, the star gets a little dimmer. The length of time it takes between dimmings and the length that those dimmings last tell us the length of the planet's year and let us guess at its orbital distance. Alternately, very massive planets make their stars visibly wobble back and forth. Measuring the period of that wobble tells us the length of the planet's year from which we can guess at its mass, velocity, and distance from the star. If a planet is massive enough, big enough, and oriented at a convenient angle we can make educated guesses about its density and temperature based on its diameter relative to its mass, and therefore its specific orbital distance. That's why most of the earliest extra-solar planet discoveries (and still the ones we know the most about) were of "super Jupiters", many of them moving very quickly in orbits extremely close to their stars. They're still guesses, of course. It may turn out, as it has many times in the past, that the universe is weirder than we think. |
if at last you do succeed, never try again
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Hawkbit
Terracotta Army
Posts: 5531
Like a Klansman in the ghetto.
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Pretty much a spot-on description above me. It is an amazing science, really.
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01101010
Terracotta Army
Posts: 12007
You call it an accident. I call it justice.
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I read this today and my immediate thought was: how do they actually know all this.
Light and gravity. We can cheat with stars since we can discern their temperature based on which spectral lines they display, and from their temperature and composition we can pretty precisely determine their mass and diameter. As a large diameter planet crosses between the star it orbits and us, the star gets a little dimmer. The length of time it takes between dimmings and the length that those dimmings last tell us the length of the planet's year and let us guess at its orbital distance. Alternately, very massive planets make their stars visibly wobble back and forth. Measuring the period of that wobble tells us the length of the planet's year from which we can guess at its mass, velocity, and distance from the star. If a planet is massive enough, big enough, and oriented at a convenient angle we can make educated guesses about its density and temperature based on its diameter relative to its mass, and therefore its specific orbital distance. That's why most of the earliest extra-solar planet discoveries (and still the ones we know the most about) were of "super Jupiters", many of them moving very quickly in orbits extremely close to their stars. They're still guesses, of course. It may turn out, as it has many times in the past, that the universe is weirder than we think. That's a damn fine basic description of it and much more conducive to me actually understanding. So what do they compare it to? I'd think to have some sort of confidence, they'd have to have some sort of basis already to make the claim. |
Does any one know where the love of God goes...When the waves turn the minutes to hours? -G. Lightfoot
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Krakrok
Terracotta Army
Posts: 2190
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Lantyssa
Terracotta Army
Posts: 20848
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Spectral emissions can be made by taking pure elements and burning them. They'll only emit light at certain wavelengths and temperature ranges. By comparing those with the light emitted by a star, they can figure out its composition and temperature. The lines are additive, so they're very easy to analyze with computers. Hydrogen spectral linesNow red shifts in the spectra require a bit more processing then a direct comparison of lines, but actually help us determine distance and velocity of stellar material. |
Hahahaha! I'm really good at this!
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pxib
Terracotta Army
Posts: 4701
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So what do they compare it to? I'd think to have some sort of confidence, they'd have to have some sort of basis already to make the claim.
We don't have much confidence about planets, and the rules keep changing as we discover new ones. We assumed that planetary systems would basically look like ours, and it turns out they don't. Take, hot Jupiters for example. Those giant planets orbiting very near to their stars. They shouldn't be able to form as close to their stars as they are, that amount of gas wouldn't be able to coalesce in the heavy solar winds and limited material supply of that part of an accretion disc... yet there they are. Generally it's believed they migrated there from wherever they formed, a process that would be devastating to any small planets like ours in orbits they had to cross. What we know a lot about are stars. By measuring twice a year from opposite ends of Earth's orbit, astronomers triangulating our distance to about a thousand nearby stars and then charting those by color and brightness gave us probably the most famous graph in astronomy. Since the stars on the graph seem to fit into orderly groups, they've assumed that all stars everywhere would fit into similar categories. With that assumption, they make educated guesses about the location of stars too distant to triangulate (the vast majority of them) based on how bright they are relative to their color. Correcting for ambiguous cases by checking the spectral lines, since different elements are apparent in the upper atmospheres of, for example, red giants of different sizes and temperatures. They might be wrong about the particulars like nobody guessed about migrating Jupiters. It's all math resting atop other math, with some assumptions based on the fundamental idea that there's nothing unusual about the particular place we live and so our the rest of the universe will be pretty much like our observable slice. That's not, it turns out, a 100% safe assumption so every once in a while somebody finds a fundamental error and absolutely everything has to be recalculated. It's kind of awesome. |
if at last you do succeed, never try again
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Sand
Terracotta Army
Posts: 1750
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