Starship Asterisk*

TrES 2b: Dark Planet

Explanation: Why is this planet so dark? Planet TrES-2b reflects back less than one percent of the light it receives, making it darker than any known planet or moon, darker even than coal. Jupiter-sized TrES-2b orbits extremely close to a sun-like star 750 light years away, and was discovered producing slight eclipses in 2006 using the modest 10-cm telescopes of the Trans-Atlantic Exoplanet Survey (TrES). The alien world's strange darkness, however, was only uncovered recently by observations indicating its slight reflective glow by the Earth-orbiting Kepler satellite. An artist's drawing of planet is shown above, complete with unsubstantiated speculation on possible moons. Reasons for TrES-2b's darkness remain unknown and are an active topic of research.

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Maybe it gathered up all the DUST and debris in that solar system.

:-----===== <smiley with a telescope.

Alien World Is Blacker than Coal
http://asterisk.apod.com/viewtopic.php?t=24873

It appears that nobody told the artist about it only reflecting one percent. It should be pitch black in the painting and the moon in front of it would be invisible.

Heavy carbon composition?

I don't remember an APOD ever being an illustration before. While there is a lot of beautiful space art out there, it is mostly subject to speculation and conjecture, and therefore not truly scientific. Is this a new precident for APOD?

Almost all of the pictures you see on APOD are taken in black and white and colored in based on the assumed composition. I'd say 5-10% are artists renditions.

Benbrilling wrote:It appears that nobody told the artist about it only reflecting one percent. It should be pitch black in the painting and the moon in front of it would be invisible.

Actually what the caption failed to mention is that it is speculated that the planet is so hot it actually glows. That's where the red on the planet is coming from. And the moon is reflecting light from its sun, not the planet.

It seems to me something rather misleading about the sketch is that the planet is shown as being on this side of its star. But on this side of its star, with the star as a backdrop, surely any planet would look darker than this one. Where the darkness must really be evident is when it's on the far side, almost behind the star. I presume that's where the darkness must have stood out in the data as compared to other planets which would be bright (though dim compared to the star of course), then that brightness would disappear from the total incoming light, then reappear as the planet finished passing behind the star and came back into view.

Artistic license, but misleading.

revloren wrote:I don't remember an APOD ever being an illustration before.

http://apod.nasa.gov/apod/ap110401.html
http://apod.nasa.gov/apod/ap110401.html
http://apod.nasa.gov/apod/ap110128.html
http://apod.nasa.gov/apod/ap101114.html
http://apod.nasa.gov/apod/ap101001.html
http://apod.nasa.gov/apod/ap100707.html

And so on back to the very first APOD.

The coals in my bbq are black also. Why is this such a mystery?

A question about energy balance occurs to me. A key word here is "reflected". So the planet is absorbing immense amounts of energy; it must be re-radiating it at different wavelengths, and one of the links I've seen refers to it being like glowing embers. Does anyone here know what kind of information we've been able to get from the spectrum of that re-radiated energy?

Also back to my artistic license comment above. It would be really, really hard to portray a dark planet against space. So hard I could probably do it as well as a real artist. I excuse that part of the artistic license. But it should be a lot darker than what we see, surely.

Oh, and do I get promoted from Ensign when I get to 100 posts?

Very few are satisfied! I liked the art! Nobody really knows what it looks like; so it's OK for the artist to use his imagination~ Anyway I copied the movie from the links.

nstahl wrote:A question about energy balance occurs to me. A key word here is "reflected". So the planet is absorbing immense amounts of energy; it must be re-radiating it at different wavelengths, and one of the links I've seen refers to it being like glowing embers. Does anyone here know what kind of information we've been able to get from the spectrum of that re-radiated energy?

Considering the kind of star that this planet orbits, a G0V type of star, slightly but not a lot hotter than the Sun, the planet might be warmed to brown dwarf-like temperatures.

http://en.wikipedia.org/wiki/Brown_dwarf writes:

Some brown dwarfs emit X-rays; and all "warm" dwarfs continue to glow tellingly in the red and infrared spectra until they cool to planetlike temperatures (under 1000 K).

So the planet won't emit much visual light unless it is hotter than 1000K.

http://en.wikipedia.org/wiki/Brown_dwarf also writes:

Because of the absorption of sodium and potassium in the green part of the spectrum of T dwarfs, the actual appearance of T dwarfs to human visual perception is estimated to be not brown, but the color of magenta coal tar dye.

Magenta coal tar dye, eh? Sounds like today's APOD planet to me. Maybe the planet looks like this.

A lot of elements and molecules have spectral signatures in the infrared part of the spectrum, so it should definitely be possible to find out the composition of the atmosphere of the planet, if its infrared signature can be separated from the signature of the star.

Ann

nstahl wrote:A question about energy balance occurs to me. A key word here is "reflected". So the planet is absorbing immense amounts of energy; it must be re-radiating it at different wavelengths, and one of the links I've seen refers to it being like glowing embers. Does anyone here know what kind of information we've been able to get from the spectrum of that re-radiated energy?

I was wondering this also -- have any IR or x-ray studies been able to be made of TrES 2b?

Another question -- I couldn't find if this planet is any closer to its sun than our solid planets (Mercury through Mars) are to our Sun. But if it is, what internal forces keep its stated gaseous form being blown away by solar winds or other solar activity?

Low light requires dark (green won't do) leaves to capture "sun"light. It's vegetation!

From wikipedia, TrES 2b has an orbital period of less than 2.5 days at a distance of ~0.035 AU, well inside the orbit of Mercury (~0.387 AU, 88 days). It was discovered in 2006 the using the transit method and confirmed later that year using the radial velocity method. What is known about its albedo, was determined from Kepler data measuring the variation in phase brightness as it orbited its star. Very little is known about this planet, or its star, which are 718 ly away.

I wonder, can this planet even have moons so close to it's sun? I wonder also, is this possibly the "beginning" of binary system?

Ann wrote:So the planet won't emit much visual light unless it is hotter than 1000K.

CfA wrote:The star's intense light heats TrES-2b to a temperature of more than 1,800° Fahrenheit

> 1250 K

tECH hIPPY wrote:I wonder, can this planet even have moons so close to it's sun?

It's an artist's illustration. TrES 2b is suspected to be tidally locked and probably does NOT have moons.

I wonder also, is this possibly the "beginning" of binary system?

TrES 2 (aka GSC 03549-02811) IS a binary.

Maybe the planet is composed of dark matter?

Jim Julian wrote:Maybe the planet is composed of dark matter?

If it were, it wouldn't be dark, it would be transparent.

Oh boy a cartoon I like cartoons easy to understand

and tomorrow a roll cloud

I will be busy tomorrow golfing so I will just say it today-a roll cloud is not astronomical

... a roll cloud is not astronomical

So planetary atmospheric phenomena are not appropriate to APOD? Or is it just that you are overly familiar with the particular planet on which the atmospheric phenomena originated? Would a picture of Martian atmospheric phenomena be alright? Or Saturnian? But not Terran. Being a Terran myself, I'm not going to stand for that kind of attitude; I'm going to sit.

Rob

I hope it's a comfy chair, Rob. There's plenty more of 'that' around.