Astronomers See the Glow of a Boiling Planet

The Bad Astronomer writes "For the first time, astronomers have detected the light from a 'super-Earth' exoplanet. The planet 55 Cancri e (with twice the radius and 8 times the mass of Earth) circles its host star every 18 hours, and is so hot it glows in the infrared. By observing in that wavelength, the astronomers measured the dip in light as the planet's glow was blocked by the star itself. This is the reverse of the usual method of detecting a planet as it blocks the light of its host star."

Comments

How cold do you think it needs to be ?

[NemoinSpace]

Before it doesn't emit infrared radiation?

Re:How cold do you think it needs to be ?

[ArcherB]

Before it doesn't emit infrared radiation?

Good point, but I would assume that it's got to be giving off quite a bit to be detectable from here.

Or maybe it's just very reflective.

Re:How cold do you think it needs to be ?

[Anonymous Coward]

They were looking at a wavelength of 4.5um - this probably isn't the peak wavelength the planet is emitting, but if it were, the source would need to be 370 C. Which I would call toasty.

Re:How cold do you think it needs to be ?

[fuzzyfuzzyfungus]

One could argue that 'infra-red' covers absolutely everything below red on the spectrum; but the accepted definition starts calling them 'microwaves' at some point. Cosmic background radiation mostly falls into that camp, below IR; but that is very chilly indeed...

Re:How cold do you think it needs to be ?

[gman003]

It's not the peak - TFA states the planet's temperature is about 2700C. Which I would call "infernal".

That does, however, explain how the IR emissions are high enough for us to detect here on Earth, light-years away - it's really, really, *really* hot.

Re:How cold do you think it needs to be ?

[blackhat1234]

According to the article (yes I know it's not cool to RTFA) it's "so close to the star that the surface temperature is probably around 2700C — or 4900F!"

Re:How cold do you think it needs to be ?

[Anonymous Coward]

Ahhh.. Crematoria.

Re:How cold do you think it needs to be ?

[girlintraining]

Before it doesn't emit infrared radiation?

Absolute zero. All objects emit infrared. Better question: What's the sensitivity of the equipment measuring this?

Re:How cold do you think it needs to be ?

[dido]

2700ÂC is not just infernal I'd think. That temperature is nearly half the temperature of the sun's photosphere (5500ÂC). Iron melts at 1538ÂC, and boils at 2862ÂC. There could be clouds of iron vapor and rains of molten iron there. If it had any kind of atmosphere it would likely be made up of iron and silicon vapor.

Re:How cold do you think it needs to be ?

[jasno]

Norfair?

Re:How cold do you think it needs to be ?

[avgjoe62]

...it's really, really, *really* hot.

Yea, but it's a dry heat...

Re:How cold do you think it needs to be ?

[Taco Cowboy]

... it's "so close to the star that the surface temperature is probably around 2700C â" or 4900F! ...

Is that the temperature for the WHOLE planet or the side which faces its sun ?

Re:How cold do you think it needs to be ?

[Anonymous Coward]

with 2700 C the dominant frequencies aren't infrared anymore. More like yellow.

Re:How cold do you think it needs to be ?

[Anonymous Coward]

If it had any kind of atmosphere it would likely be made up of iron and silicon vapor.

Interesting ... it is said that silicon-based organic chemistry life is impossible because, unlike CO2, SiO2 is not a gas but a rock. Well, it seems now we have found a place where SiO2 actually is a gas...

Re:How cold do you think it needs to be ?

[Neil Boekend]

Cosmic bacground radiation was emitted as infra red. It just has a massive redshift.
Everything above 0K emits infra red.

Re:How cold do you think it needs to be ?

[alva_edison]

If it had any kind of atmosphere it would likely be made up of iron and silicon vapor.

Interesting ... it is said that silicon-based organic chemistry life is impossible because, unlike CO2, SiO2 is not a gas but a rock. Well, it seems now we have found a place where SiO2 actually is a gas...

Sodium Oxide is too low temperature, but I think Li2O might have potential. Does anyone know the triple point of Lithium Oxide?

Re:Now, now, now's the time right now!

[Sarten-X]

To be honest, I actually I do find the posts somewhat entertaining. If this kid were writing a novel rather than trolling, I'd expect a pretty decent piece of literature to result. There's a nice blend of imagination, misdirection, and vocabulary that just appeals to me. I greatly prefer this to the post immediately below (as I write this) which includes "jason has a firm grip on shitstick".

super-Earth?

[mapkinase]

What exactly justified it to be called super-Earth? The size is close to Earth (half order of magnitude), but it is close to Venus as well, and Venus is hotter.

Re:super-Earth?

[Ironchew]

The only planets larger than Earth in the Solar system are the gas giants, so a super Earth is just a designation for a planet more massive than Earth, but not a gas giant.

Re:super-Earth?

[Anonymous Coward]

In usual exoplanet terms "super-Earth" = rocky planet larger than earth.

Re:super-Earth?

[Roger W Moore]

What exactly justified it to be called super-Earth?

Earth-like but significantly bigger than earth. The planet in question is 8 times the mass of Earth with twice the radius so roughly the same density. It might only be a factor of 8 in mass but if you saw a person with 8 times the average mass, say ~600kg, you'd certainly call them super-sized! As for temperature Venus is hotter than Earth but with a surface temperature of 460C it's decidedly nippy compared to the planet in question which is just over 1700C.

Re:super-Earth?

[Anonymous Coward]

Still does not justify calling it a super-earth, how about just calling it a planet twice size of earth? Or even better a really hot planet, given that the size of such planet has little point in the actual subject of it being really hot. We really need a better standardized way to describe the size of planets or at least use the definitions already thought up, super-earth just sound idiotic.

Re:super-Earth?

[Anonymous Coward]

super-Earth grabs more headlines

Re:super-Earth?

[Anonymous Coward]

The problem here is one of nomenclature and trying to define different terms for planets. In our Solar System there are no "super-Earth" sized planets, so until exo-solar planets were discovered there was no need for any classification for planets that sized. Basically there is a need to define planets smaller than the "small gas giants" like Neptune and Uranus and something larger than the size of the Earth or Venus.

Currently that is being called "Super Earth" because it shares many more characteristics with the Earth than it does with the gas giants.

A similar scaling problem exists for planets that are a couple times the size of Jupiter, and larger, but aren't really large enough to ignite nuclear fusion. Sometimes those are called "brown dwarfs", but "super gas giants" is sometimes used too.... odd where a dwarf is more massive than a giant.

Re:super-Earth?

[voidphoenix]

Try this: super. As a prefix, it simple means more, over, above or beyond. We have 2 kinds of planets in the Solar System: rocky and gas giant. Earth is the largest of our rocky planets, you can think of it as the flagship. So this exo is an Earth-class planet, only 8 times heavier (that's closer to a full order of magnitude than half). A super-Earth. A , where the baseline is Earth. Get it?

Re:super-Earth?

[voidphoenix]

A dwarf human is still much larger than a giant ant. :)

Re:super-Earth?

[saveferrousoxide]

What exactly justified it to be called super-Earth?

It's bigger, stronger, faster, shoots infra-red beams, and, the dead give-away, has a red cape. Yeah. I went there.

Re:Now, now, now's the time right now!

[tibit]

Get off your lazy ass and have a current version for Mac, and an HTML version for at least both platforms, will you? Less trolling, more doing.

Sauna world

[circletimessquare]

I suggest we send Finnish astronauts. They actually like this sort of place.

"Cosmonaut Hämeenniemi! Have you reached the planet, what is it like!"

(long delay)

"Shhh... I'm relaxing"

Re:Sauna world

[Ollabelle]

I think you mean to send Sam Magee

^_^

[Anonymous Coward]

A watched planet never boils...

Re:^_^

[rossdee]

But it started boiling before we started watching it.
So Boil's law is not broken.

God sucks at design

[Anonymous Coward]

Why did God design so many planets inhospitable to life? The universe seems a little more empty when you think there are so many planets that can't support life.

Re:God sucks at design

[GPS Pilot]

So you have created a universe with a better ratio of hospitable-to-inhospitable planets?
No?
Didn't think so.

Re:God sucks at design

[tbird81]

Leave the AC alone. At least he exists!

Re:God sucks at design

[Anonymous Coward]

I browse at +1. I don't believe in Anonymous Cowards.

Re:God sucks at design

[flirno]

We have no idea if they are really inhospitable to life. They are merely inhospitable to life as we know it. But, the bare fact is we don't know much, we have only a single working model to compare against which is hardly a scientific sample to draw any conclusions with.

you should have two dips

[tinkerton]

One small dip is when the planet is covering the sun.A larger dip is when the sun is covering the planet.
  S+P vs S vs S +P - coveredfractionofsun*S.

When the planet is colder the first dip is larger and the second dip is less. With a hot planet I think both dips may well be measurable.

Re:you should have two dips

[Neil Boekend]

The dip when the planet is covering the sun shoud be bigger, assuming the sun is hotter than the planet.
Sun before planet => intensity = intenisty of only the sun.
Sun behind planet => intensity = intensity of the sun - intensity of blocked part of the sun + intensity of the planet
sun and planet besides eachother => intensity = sun + planet

Re:you should have two dips

[Anonymous Coward]

Judging by the two above posts, I'd say two dips indeed.

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Every 18 hours?

[Anonymous Coward]

Something isn't right here.

Even if the planet were so close to the star that it was in the corona, If it were a star the size of our sun, the speed of the planet would be, really really big.

Anybody have any numbers on this?

Lead

[Anonymous Coward]

Hot enough to boil lead more like.

Article and its references are vague

[Anonymous Coward]

The orbital image leaves a lot to be desired... Come on, 1/3 of the phase is shown! Thanks to Nasa's usual attempts to hoard its images, here has a little more information on that orbital phase.

This plot of data from NASA's Spitzer Space Telescope reveals the light from a "super Earth" called 55 Cancri e. The planet is the smallest yet, beyond our solar system, to reveal its direct light. Super Earths are more massive than Earth but lighter than gas giants like Neptune. While this planet is not habitable, the observations are an important milestone toward being able to eventually perform a similar technique on even smaller, potentially Earth-like planets.

The plot shows how the infrared light from the 55 Cancri system, both the star and planet, changed as the planet passed behind its star in what is called an occultation. When the planet disappeared, the total light dropped, and then increased back to normal levels as the planet circled back into view. The drop indicated how much light came directly from the planet itself. This type of information is important for studying the temperatures and compositions of planetary atmospheres beyond our own.

Although they try to explain what is theorised to happen, HTF does the infrared dip when the planet passes behind the star? Is the star not the total possible output of IR available in that system? i.e. The effects of IR don't stack when the planet is in front of the star; you don't get more output from the system than is available from the source! The planet AFAICT is dark sided, relative to us, when passing the forward facing part of the star, relative to us, which means it should be much cooler on that side than the star facing side blasting towards earth when as the planet egresses the occultation, from the opposite in which they ascribe above...

Without any mention or reference to the stars wobble regarding the planet to disprove my theory, I suspect the orbital times are more likely half that TFA suggests which means it is seriously nipping around. Maybe it is too difficult to get a wobble indication due to the fast speed of the planet and the distance from the star? I doubt it though. I speculate that the dip in question is the time it takes to pass the front of the star, relative to us.

Would someone care to make a speed calculation based on the possible variables such that: the star is similar in size to ours, the planetary orbit is 18hrs (imo 9hrs).

</bonnetrattler>

Re:Article and its references are vague

[Anonymous Coward]

Ok, this is much clearer

They are certainly lacking the combined time graph plots showing a full orbital phase transition of the planet versus both light (0.04%) and IR (0.001%) with respect to the star to help visualise what is going on.

From here on I will ignore the light component and focus (pun intended) on whats happening with the IR.

The confusing part is the article I linked mentions it dips the IR as it goes around the back, occults with reference to planet==>star==>earth, and refers to a dip of 0.001% in IR output towards Earth and yet they show the dips on the side of the star in the image although the dip is really occurring when the planet is not reflecting back to us, i.e. in occultation such that p==>s==>e and to even a lesser extent, slight here come-on, dip when the occultation is such that s==>p==>e. The extra IR is in fact coming from the other side of the star reflecting from the planet at the stars left and right sides with respect to earth as the planet outer ingresses and outer egresses, hence not a dip... The dip is misleading in their context. The dip in IR is in fact occurring during the planets inner ingress, occultation then inner egress of the star at the back side of the star; an increase in IR occurs as you see the planets forward star facing side, in tidal lock (again due to an increase of IR via reflection of the dark side of the star from the stars outer ingress and outer egress sides of the planet therefore increasing the total forward IR output that we see, in fact it could be said the star is now 1.001 of total IR output luminosity towards earth). The time seeing the IR dip is > than the time not seeing the IR dip. I would therefore be inclined to say that this is a leading spike before and after occultation of the p==>s==>e in that scenario. And that the true IR output of the star==>earth can only be seen as an average of this whole process. (I say this because the planets outer ingress and outer egress at occultation of s==>p==>e would still provide, very-very-very marginally, some IR much-much-much less than the 0.001% observed upon reflection of the star and thusly cannot be readily dismissed as being insignificant, neutrinos are insignificantly small!)

</$0.02>