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An Ultrahot Exoplanet Has Metallic Skies

96 points by yaseen-rob 8y ago

imhoguy 8y ago
Remids me metal based life forms[0] - mind-blowing. [0] https://www.newscientist.com/article/dn20906-life-like-cells-are-made-of-metal/ https://www.newscientist.com/article/dn20906-life-like-cells...
- Razengan 8y ago
  I wonder if the first extraterrestrial lifeforms we discover will be anything like we expect.
- _cereal 8y ago
  This reminds me about the Scaly-foot gastropod[1] mollusc which "possesses a trilayered structure comprised of a mineralized iron sulfide–based outer layer (OL) containing greigite..."[2] [1] https://en.wikipedia.org/wiki/Scaly-foot_gastropod https://en.wikipedia.org/wiki/Scaly-foot_gastropod [2] http://www.pnas.org/content/107/3/987 http://www.pnas.org/content/107/3/987
- SlowRobotAhead 8y ago
  That article is from 2011, I wonder how much of it any continued to be developed?
phyller 8y ago
I call BS. I'm not saying the planet doesn't have iron or titanium, just that I don't think their data shows it. The researchers supposed that this planet might have iron and titanium in the atmosphere, they have an image of the star with a slight dimming from the passing of the planet across it, and they find the spectral signature of iron and titanium. The percentage of the light collected that was emitted by iron and titanium, if it existed in the atmosphere, would be so mind-boggling minuscule compared to the light of the star itself, I would think that the iron and titanium signatures would come from elements trapped in or around the star. I think if they looked hard enough they could find whatever elements they want.
- deleted 8y ago
  [deleted]
- solipsism 8y ago
  So quick to call BS without knowing what you're talking about. Transit spectroscopy is a well established scientific method. To put it simply... obviously they accounted for that.
  - phyller 8y ago
    I should apologize, I am probably, hopefully wrong. I'm still skeptical but clearly more work has been put into this than I realized and I shouldn't have been so quick to condemn it.
    - anoncoward111 8y ago
      Life is short. It's fun to have opinions if you are willing to be wrong :)
      - dwaltrip 8y ago
        I'm glad this had a happy ending! :D Sometimes I feel bad piling on a downvote train -- especially considering the psychology research showing that people usually just dig in further in such situations...
        phyller 8y ago
        To be honest, it would have been better to explain how they do the spectroscopy than to just say "you don't understand" and downvote. I should have raised a question instead of making a statement, the response should have been an explanation, instead of basically "you're an idiot" (which still no one has done as of this time). They are making the same error I did. The article posted didn't explain, the paper costs $9 to read. I wouldn't call this a productive discussion at this point. Edit: someone just attempted to explain the technology behind it, thanks amluto
Sniffnoy 8y ago
I'm confused, they say the planet doesn't emit light of its own, but if it's that hot -- hotter than most stars, they say -- shouldn't it be giving off blackbody radiation in the visible spectrum?
- grigjd3 8y ago
  Size matters. To be clear, it very much likely gives off BB radiation, but it may not be big enough to be detectable here.
  - jessriedel 8y ago
    Eh, it's double the radius of Jupiter, which makes it about one fifth that of the sun, right? So the apparent BB area is a 25 times less than a star, which is small but not crazy small. More importantly, the amount of light from the parent star filtering through the planet's atmosphere would seem to be much less than the amount emitted directly by the planet, since the apparent surface of the former is only a thin ring of area around the surface for the latter.
    - grigjd3 8y ago
      Several things: stars get much cooler than the sun, a factor of five in radius is a factor of 25 in surface area, the heat may be focused on the side pointing at the star (meaning the star masks the light), and light from the star could be overwhelming the light emitted by the planet. Astronomy is filled with orders of magnitude.
      - jessriedel 8y ago
        You repeated one of my own points back to me and then condescended down to me about not appreciating orders of magnitude. (I'm a physicist myself.) The whole purpose of my comment is that 25 is not that small of a factor on astronomical scales and it suggests the BB radiation of the planet itself would be detectable. As it turns out, this is the case > As a result, [the planet] has an extremely high equilibrium temperature, assuming zero albedo and perfect heat redistribution, of ∼4050 K. This is as hot as a late K-type star, and thus we expected a large thermal emission signal, which we easily confirmed with our z'-band detection of the secondary eclipse with a depth of ∼ 0.1% (Figure 1). This measurement implies an even hotter day-side temperature of ∼ 4600 ± 150 K, likely indicating poor redistribution of energy to the night side of the planet and a temperature closer to that of a mid-K star. https://arxiv.org/pdf/1706.06723 https://arxiv.org/pdf/1706.06723 Note also that, contra your suggestion that the planet might just be too cold on night side to have significant BB radiation, the night-side temperature is only 15% lower than the mean.
andrescoin 8y ago
Impressive! Do you guys are looking for interns?
ereyes01 8y ago
It's super impressive to me how much mileage we've gotten out of the Hubble Space Telescope. The article implies that this finding was made found in old data once the researchers knew what to look for. Does anyone know how much data from Hubble is sitting there, and whether it's publicly available? EDIT: I found this: https://hla.stsci.edu/ https://hla.stsci.edu/

96 points by yaseen-rob 8y ago

Remids me metal based life forms[0] - mind-blowing. [0] https://www.newscientist.com/article/dn20906-life-like-cells-are-made-of-metal/ https://www.newscientist.com/article/dn20906-life-like-cells...

Razengan 8y ago
I wonder if the first extraterrestrial lifeforms we discover will be anything like we expect.
_cereal 8y ago
This reminds me about the Scaly-foot gastropod[1] mollusc which "possesses a trilayered structure comprised of a mineralized iron sulfide–based outer layer (OL) containing greigite..."[2] [1] https://en.wikipedia.org/wiki/Scaly-foot_gastropod https://en.wikipedia.org/wiki/Scaly-foot_gastropod [2] http://www.pnas.org/content/107/3/987 http://www.pnas.org/content/107/3/987
SlowRobotAhead 8y ago
That article is from 2011, I wonder how much of it any continued to be developed?

phyller 8y ago

I call BS. I'm not saying the planet doesn't have iron or titanium, just that I don't think their data shows it. The researchers supposed that this planet might have iron and titanium in the atmosphere, they have an image of the star with a slight dimming from the passing of the planet across it, and they find the spectral signature of iron and titanium. The percentage of the light collected that was emitted by iron and titanium, if it existed in the atmosphere, would be so mind-boggling minuscule compared to the light of the star itself, I would think that the iron and titanium signatures would come from elements trapped in or around the star. I think if they looked hard enough they could find whatever elements they want.

deleted 8y ago
[deleted]
solipsism 8y ago
So quick to call BS without knowing what you're talking about. Transit spectroscopy is a well established scientific method. To put it simply... obviously they accounted for that.
- phyller 8y ago
  I should apologize, I am probably, hopefully wrong. I'm still skeptical but clearly more work has been put into this than I realized and I shouldn't have been so quick to condemn it.
  - anoncoward111 8y ago
    Life is short. It's fun to have opinions if you are willing to be wrong :)
    - dwaltrip 8y ago
      I'm glad this had a happy ending! :D Sometimes I feel bad piling on a downvote train -- especially considering the psychology research showing that people usually just dig in further in such situations...
      - phyller 8y ago
        To be honest, it would have been better to explain how they do the spectroscopy than to just say "you don't understand" and downvote. I should have raised a question instead of making a statement, the response should have been an explanation, instead of basically "you're an idiot" (which still no one has done as of this time). They are making the same error I did. The article posted didn't explain, the paper costs $9 to read. I wouldn't call this a productive discussion at this point. Edit: someone just attempted to explain the technology behind it, thanks amluto

Sniffnoy 8y ago

I'm confused, they say the planet doesn't emit light of its own, but if it's that hot -- hotter than most stars, they say -- shouldn't it be giving off blackbody radiation in the visible spectrum?

grigjd3 8y ago
Size matters. To be clear, it very much likely gives off BB radiation, but it may not be big enough to be detectable here.
- jessriedel 8y ago
  Eh, it's double the radius of Jupiter, which makes it about one fifth that of the sun, right? So the apparent BB area is a 25 times less than a star, which is small but not crazy small. More importantly, the amount of light from the parent star filtering through the planet's atmosphere would seem to be much less than the amount emitted directly by the planet, since the apparent surface of the former is only a thin ring of area around the surface for the latter.
  - grigjd3 8y ago
    Several things: stars get much cooler than the sun, a factor of five in radius is a factor of 25 in surface area, the heat may be focused on the side pointing at the star (meaning the star masks the light), and light from the star could be overwhelming the light emitted by the planet. Astronomy is filled with orders of magnitude.
    - jessriedel 8y ago
      You repeated one of my own points back to me and then condescended down to me about not appreciating orders of magnitude. (I'm a physicist myself.) The whole purpose of my comment is that 25 is not that small of a factor on astronomical scales and it suggests the BB radiation of the planet itself would be detectable. As it turns out, this is the case > As a result, [the planet] has an extremely high equilibrium temperature, assuming zero albedo and perfect heat redistribution, of ∼4050 K. This is as hot as a late K-type star, and thus we expected a large thermal emission signal, which we easily confirmed with our z'-band detection of the secondary eclipse with a depth of ∼ 0.1% (Figure 1). This measurement implies an even hotter day-side temperature of ∼ 4600 ± 150 K, likely indicating poor redistribution of energy to the night side of the planet and a temperature closer to that of a mid-K star. https://arxiv.org/pdf/1706.06723 https://arxiv.org/pdf/1706.06723 Note also that, contra your suggestion that the planet might just be too cold on night side to have significant BB radiation, the night-side temperature is only 15% lower than the mean.

andrescoin 8y ago

Impressive! Do you guys are looking for interns?

ereyes01 8y ago

It's super impressive to me how much mileage we've gotten out of the Hubble Space Telescope. The article implies that this finding was made found in old data once the researchers knew what to look for. Does anyone know how much data from Hubble is sitting there, and whether it's publicly available? EDIT: I found this: https://hla.stsci.edu/ https://hla.stsci.edu/