Slashdot Mirror
Extrasolar Planet's Light Observed
Last week we ran a
story
about a visually-detected planet orbiting HD 209458 - its star dimmed when the planet passed before it.
Today,
Richey points us to a
"a BBC story about how astronomers have actually picked up light reflecting off an extrasolar planet. They've managed to perform a basic analysis of its atmosphere from it." Check out the three elements they believe they found.
Now, Si and Mg should be pretty rare in the star, so that could account for being able to see those elements, but I would have thought O (along with C and N) would be at least somewhat abundant in the star. In this case I would guess the possibilities are that the O lines don't saturate, or that the stellar O is mostly OII or OIII (singly and doubly ionized, respectively), so that the stellar lines don't coincide with the planetary lines.
As a side note, I think the conventional wisdom of "oxygen as an indicator of life" wouldn't apply here because this planet is likely hot enough that the gas is mostly atomic rather than molecular. Remember that the reason why elemental oxygen is supposed to be so uncommon in planetary atmospheres is that it is so reactive. Thus, the argument goes, if it is there some sort of process (like life) must be replacing it. On the other hand, if the environment is hot enough to dissociate most molecules anyhow, then oxygen's reactivity is less important, so it's not surprising to see it fairly abundant.
-r
There's a big difference here though. They're not looking at a planet, like you'd look at Mars. They're looking at a star.
The difference of angle between the star and the planet from over 50 light years away is way too small to see. So, they point the instruments at the star, then record everything. The stuff that varies on a cycle of 3.3 days they say is from the planet or due to it. Then it's a matter of analysis.
Do you know all the crazy stuff that happens in a star? The fusion cycle is ridiculous. All kinds of wacky things happening. Carbon exists in stars (albeit for a very short period of time) sometimes. You get all sorts of wacky spectral lines from different stars. Anything that star is putting out is going to cancel the signal we can say is from that planet. Probably the only reason we can see O, Si, and Mg is that that is extremely unlikely stuff to find in a star.
Yes, if you can see the planet directly, get reflected light directly, then you can analyse the hell out of it. But we're not seeing the planet. We're seeing the star, and filtering the planet out of that.
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- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
Woo, oxygen. If I remember my astrobiology correctly, this would be taken as a sign of life if it weren't on a planet four times the mass of jupiter, and with a year of less than four of your Earth days.
Note to everyone who reads science fiction: silicon has a lot of the properties of carbon; this does not mean that silicon-based life (as we sort of know it) is possible. Don't jump to conclusions.
You've got to wonder, though, what the astronomers have discovered when they refuse to talk to the BBC.
Could someone tell me why there are heavier elements like Silicon and Magnesium and no Hydrogen?
But: the presence of oxygen is revelant, in the sense that it's a pretty high coincidence that oxygen can be found there, if it is indeed due to chance. This is the same argument than when the first exoplanets were discovered: people pointed out they were large, surely lifeless masses of gas, but the point is not that. The point is, planets *do* exist out there, around other stars. That's mighty big, as it shows that planet formation is universal, and not a freak accident.
From there, it only looks good. If now we can observe the light off a planet (though I bet the specific conditions for observing such a light is in the range of probabilities of seeing a gravitational lens effect), it means we're moving forward to the day we'll be able to observe an Earth-type planet up there somewhere. And from there, it's a simple question of sending a radio signal directly at that planet.
So, stop saying it's irrevelant. It's a small step, but it's revelant as hell. Ten years ago, I could only dream that scientists would pick out the signs of an extra-solar planet. Now the possibility of finding a planet the size of our own is becoming more and more a reality. And if that's not something to celebrate, I don't know what is.
"The wages of sin is death but so is the salary of virtue, and at least the evil get to go home early on Fridays."
Think about it.. They say there is a planet. They are able to see light reflecting from it. They say they found Oxygen. That means that life like ours could be capable on that planet. Taking both of these statements as true, then why cant we "hear" anything from this planet? If we can see it, we should be able to hear it. It must be that, THERE IS NOTHING TO HEAR! And if thats the case, then there is no life, or at least intelligent life. To prove my theory that WE ARE THE ONLY LIFE IN THE UNIVERSE! -matt
Lessee... Planet is 50 lightyears away from earth, assuming a nice round estimate of Radio waves being 100 times slower (Which is wrong and giving radio waves a much higher speed than they deserve) it would take 5000 years for anything to be audible here. If they were broadcasting Radio waves 5000 years ago then they've either blown themselves up or moved past radio waves long ago. And likely abandoned the planet or developed in a manner which we can not guess. Also, since they would of neccesity be silocon based I imagine they may not have any concept of many things we take for granted, sight and sound being 2 of them. As they would be VERY VERY close to their sun and going VERY VERY Fast. A rather harsh environment, eh?
Kintanon
Check out JoshJitsu.info for Brazilian Ji
Well, it should have been called sunlight, but then the Moon went ahead and patented the million year-old technology first.
"The wages of sin is death but so is the salary of virtue, and at least the evil get to go home early on Fridays."
It is most unlikely (see below) that there is elemental magnesium and silicon in the planet's atmosphere - so it must be that they detected molecules containing magnesium, silicon and oxygen (i.e. almost certainly MgO and SiO.) The reporter has reported the elements but not the molecules.
MgO and SiO are so stable that they are present as molecules in the atmospheres of cool stars - around 3000K. For them to be in elemental form in the planet's atmosphere, it must be hotter than this.
Here is a back-of-the-envelope calculation: The relationship between orbital radius and period is P^2 proportional to a^3 (a=semi-major axis of the orbit) (This is one of Kepler's laws.) Strictly speaking, we need the mass of the star in there also, but we are told the star is 'slightly larger and brighter than the sun', so I will assume it has solar mass and luminosity for simplicity.
The period is about 0.01 that of the earth around the sun, therefore the orbit radius is about cube root(1e-4) approx equals 0.05 that of the earth - i.e. 1/20 AU. The incident energy from the star goes as inverse r squared, so will be 400 times brighter than on Earth. The equilibrium temperature for a black body goes as the fourth root of this, so will be about 5 times greater than for the Earth.
The black body equilibrium temperature of the earth is below freezing - say 250K (we gain from the greenhouse effect) so this planet will be around 1250K - short of what is needed to dissociate MgO and SiO by a factor of about 3. (This is somewhat of an underestimate as the star is more luminous than the sun. This is partly counteracted by the fact that with a more massive star, the planet is further away for the same orbital period.)
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Lessee... Planet is 50 lightyears away from earth, assuming a nice round estimate of Radio waves being 100 times slower (Which is wrong and giving radio waves a much higher speed than they deserve) it would take 5000 years for anything to be audible here.
One-hundred times slower than the speed of light? Ummm, no, sorry, light's nothing but electromagnetic radiation at a lower frequency than that which we commonly associate with the use of "radio." It's all the same thing, ergo, moving at the same speed.
If they were broadcasting Radio waves 5000 years ago then they've either blown themselves up or moved past radio waves long ago.
I'm by no means a physicist, but as far as I know, the electromagnetic spectrum is all there is. There's no faster, more efficient way to communicate than that. So they may well have moved on to higher frequencies (x-, micro-, gamma rays, etc.) than what we normally use but they would still be detecable by our instruments.
-jay
The word you're looking for is "extrasolar" - outside the solar system (the planetary system of our sun, Sol). All planets other than Earth are "extraterrestrial", including the local ones like Mercury and Jupiter.
And in response to a different message, Jupiter's surface gravity is about 2.5 G. Yes, Jupiter has way more than 2.5 times Earth's mass, but it has a much larger radius, too; g = (G*m1*m2)/r^2
-- Alastair
As I read this article, I had an interesting thought come to mind... what if we do discover a distant planet, and what if we do observe parameters indicating some form of life on that Planet?
In 10 years time, we'll supposedly have the technology to start taking pictures of distant planets - what if we eventually take a picture of a planet that definitively indicates that life exists on that planet (hey, are those *cities*?)?
What do we, as a species, do next?
We know we have distant neighbours. They're definitely some sorta life form, say. It'll take us 10,000 years to get there, at least using modern technology - what do we do about it?
I personally don't have a hard time envisioning a massive shift in cultural focus were this to happen - mankind may in fact become more unified around the goal of reaching out to our neighbours and establishing trade with them, or some sort of Unification of species (cultural, trade, religious, sexual, etc).
The ramifications are interesting - do we as a species make it a goal to contact this distant civilization in some fashion, or do we just leave it at that and go on pretending they don't exist, since for all intents and purposes, the existing Earth generation will never have contact with them? Well, I can imagine our own species undergoing massive shifts too - perhaps Earth wars will be fought over whether to contact our neighbours or not, who knows?
I'm sure there have to be some pretty good speculative fiction pieces on this sort of subject - do any Slashdotters know of authors that have treated this subject in any particular degree of quality or style? I'm inclining towards writing a short story myself, based on this subject... but surely there have to be some fairly decent authors out there who have already approached this same issue from a "what effect does it have on mankind *now* as we know it?" stance.
; -- the corruption of government starts with its secrets. a truly free people keep no secrets. --
Conincidentally, just a few weeks ago, the professor for an imaging class I'm taking discussed the method of detecting planets by measuring the reflected light off the planet. Basically, we wait for a period of increased solar activity (which causes a spike in the received signal), and then take the autocorrelation of the received signal. We should then see 2 spikes in the autocorrelation function: one corresponding to the direct emission from the star, the other from the reflection off the planet.
In practice however, it doesn't work that well (and in fact hadn't been applied sucessfully before this) since the reflection off the planet is very weak and drowned by noise.
...will the Chinese send a manned craft there?
...will the Chinese launch a cyber attack against that planet? Of course, using modified, evil closed-source seti@home clients?
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do scientists know have firm belief in something that they once doubted?
Although scientists were pretty sure about the existence of planets, they weren't positive; as you said, seeing is believing. There were other explanations for the phenomena, but of all the possible answers, a planet was by far the most plausible. You can consider this a confirmation that is nice, but wasn't really necessary for proof.
I doubt the same technique would find a moon as well, but you never know.
Could someone tell me why there are heavier elements like Silicon and Magnesium and no Hydrogen?
From the article, it sounds like they looked at the spectra of the star and planet, and saw what varied over 3.3 days. I'm assuming the hydrogen and helium spectra from the star was so much higher in magnitude than the hydrogen and helium from the planet that differences caused by the planets orbit were undetectable.
Oxygen, silicon and magnesium must be rare enough in the star to allow a noticeable difference in the spectra when the planet rotates.
George
Its most likely in gaseous form. I doubt that the gasses would "boil off" (although hydrogen can "evaporate" -for lack of a better word- from a planets atmosphere by being subjected to solar winds and other effects.) The sheer mass of this planet makes it likely that the gas would remain, or at least the heavier elements would. Given its size it probably heats itself (Hydrogen fusing core similar to Jupiter? Perhaps.)
The proximity to the star it orbits coupled with its own internal heat would make the elements detected most likely be present in a gaseous form.
This is coupled with the fact that a gas spectograph was most likely taken of the planet. This is how spectograpy (sp) works. AFAIK, unless they used the amount of light NOT reflected by the planet, but then that would not rule out a great deal of elements, so how could they have detected these three?
The answer is again A light spectograph of gasses.
The reason is because the article cleary states that they detected reflected light not absorbed. Thus, it IMO is not a rock. Given its mass, I would favour a gas giant.
Try to hack my 31337 firewall!
I remember reading books on astronomy when I was growing up; there are 9 planets, many moons, and they're all in our solar system. Scientists think there are probably other planets out there, but they can't be sure.
The books I was reading, in class and outside, were written in the late 80s and early 90s. An now, 10 years later, we've discovered scores of planets, and even seen light from one of them! It's amazing! I remember being angry to hear that funding for space travel/exploration was being cut every year; I could never say why I knew we needed to continue this research, but I just knew we did. We HAVE to go to Mars. We HAVE to send out more deep space probes. We HAVE to go back to the moon.
We're explorers. We always have been. These findings of planets have made it to the late night talk show monologue jokes, Comedy Central's The Daily Show, and most major media outlets. There's interest again. I just hope we keep it up and make sure we don't stop exploring because "there's better things we could be doing with our money"
The Good Reverend
Okay, let's summarize:
:-)...
-Magnesium, silicon and oxygen found (no proportions given out).
-Huge planet. 4 Jupiter masses
-3.3 day year
Well, if it's 4 J-masses, and whips that fast around it's sun, I'd bet it's always facing the same side towards the sun. Probably causes some pretty damn spetacular tides on that sun too (think solar matter waves 1000 miles high
Now oxygen != life guaranteed. They give no clue on how much O^2 has been found, nor if it's cool enough to be O^2 in the first place. If the place is too hot, molecules might not be an option. This is a possibility since it's mighty close to the sun, remember?
Still cool. Probably the only reason they can get any light off it it because it is so close to it's sun, and gets enough light to reflect well. Also, it's damn lucky that the ecliptic planes cross just right to see it at all.
Life is probably out. Jupiter is what, 20 G's? and this thing is around 80? Nah. My best guess: it's so damn hot and massive that it's nearly a star anyway. Give it a few hundred years or so, it'll crash into the star itself, and give the astronomers some real eye-candy.
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- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
In this case, the presence of oxygen in the atmosphere does not indicate the presence of life. In fact, given the two other elements detected (silicon and magnesium), it indicates a climate that is singularly inhospitable to any biology at all.
The atmosphere is vaporized rock. Now that's hot.
Rocks, at least the crustal rocks on Earth, consist mainly of oxygen, silicon, and magnesium, with a few trace elements to make things interesting.
Given that this planet is so close to its star, it's not surprising that the surface tempurature is hot enough to boil rocks.
That's "Mr. Soulless Automaton" to you, Bub.
... so I don't know a whole lot about these things. But I think it's a very interesting development for them to find Oxygen. Very, very interesting. It makes me ask an important question, though:
:)
Why?
I don't know a whole lot about planetary formation, but I seem to recall there was a reason that Oxygen isn't usually found in the big gas giants, and things like Hydrogen and helium are. So one asks the question: Why is there oxygen there? Why is there, of all things, silicon there?
The current theory, I think, about how this particular planet formed is that it was created way out where it ought to have been, and then gravitated (so to speak) inward. But would that account for these odd elements in the atmosphere?
Again, I don't know much about the creation of the universe, so if there's any astrophysicists out there, I'd love to find out what's going on here
-Denor
Or suppose the life on planet X is intelligent but huge and slow - like million-year lifespans and taking a year just to get a word out. Would we have any incentive to talk to them? Would we even know to try?
Or will it really turn out that all intelligent life in the galaxy is just English-speaking humanoids with wrinkled noses?
One-hundred times slower than the speed of light? Ummm, no, sorry, light's nothing but electromagnetic radiation at a lower frequency than that which we commonly associate with the use of "radio." It's all the same thing, ergo, moving at the same speed.
If they were broadcasting Radio waves 5000 years ago then they've either blown themselves up or moved past radio waves long ago.
I'm by no means a physicist, but as far as I know, the electromagnetic spectrum is all there is. There's no faster, more efficient way to communicate than that. So they may well have moved on to higher frequencies (x-, micro-, gamma rays, etc.) than what we normally use but they would still be detecable by our instruments.
My mistake if everything travels the same speed.
As to the second point you make the erroneous assumption that we have discovered everything there is to discover. I'd not be so quick to hop on that horse if I were you.
Kintanon
Check out JoshJitsu.info for Brazilian Ji
No details of the work? No peer review?
It's exciting news, but I think we should really wait for some more information and confirmation.
What's interesting is the note in the article regarding observation with the next generation of telescopes and astronomical equipment. Aside from confirming this, what else might be done with the next generation of observation equipment?
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