True Color Of An Exoplanet Discovered For The First Time

[stevebowers]

http://www.popsci.com/science/article/20...first-time

Illustration of HD 189733b NASA, ESA, M. Kornmesser


Looks a bit like Earth, doesn't it? You wouldn't find this planet very comfortable, however. Called HD 189773b, it's 1,000 degrees Celsius on its surface and it rains glass. Sideways.

HD 189773b looks like Earth because it's blue. Astronomers have determined its true color, a first for an exoplanet, or a planet orbiting a star other than Earth's own sun.

Using data from the Hubble Space Telescope, a team of European and American astronomers measured the light reflection off of the exoplanet. The team had to isolate light reflecting off the planet from light from its star (the exoplanet orbits the star closely). The researchers used measurements from before, during and after the planet appears to go behind its star, in relation to Earth.

In general, HD 189773b has been well studied by Hubble and other telescopes because it's relatively close to Earth, 63 light-years away.

The blue color is thought to come from silicate particles in the planet's atmosphere, which scatter blue light. Because of the planet's surface temperature, the particles could condense to form glass. These glass grains would then fly around in the planet's 4,000 mph (7,000 kilometers per hour) wind. Ouch.

[stevebowers]

I was intrigued by the cloud patterns on that simulation, so I've tried to replicate them myself- here it is (now renamed Blueglass)

[Drashner1]

Hmm. 63 ly is well inside the Inner Sphere. I wonder what Terragens civ has done with the place...

Todd

[mark_ryherd]

I was intrigued by the cloud patterns on that simulation, so I've tried to replicate them myself- here it is (now renamed Blueglass)

What is the large bright star in the upper right corner? It looks too far away to be the primary (with the planet only having an orbital period of a couple days).

[mark_ryherd]

Hmm. 63 ly is well inside the Inner Sphere. I wonder what Terragens civ has done with the place...

Todd

The primary star is a variable star and the planet is a ~1000K with glass rain and winds calculated at 9,700 km/h, this doesn't strike me as all as the a place to live. Maybe there is a group or individual out there desperate enough to make a go of it.

[stevebowers]

I was intrigued by the cloud patterns on that simulation, so I've tried to replicate them myself- here it is (now renamed Blueglass)

What is the large bright star in the upper right corner? It looks too far away to be the primary (with the planet only having an orbital period of a couple days).

That will be HD 189733 B, I expect. The planet and the companion star rather confusingly share the same name, distinguished only by case.

[stevebowers]

Hmm. 63 ly is well inside the Inner Sphere. I wonder what Terragens civ has done with the place...

Todd

The primary star is a variable star and the planet is a ~1000K with glass rain and winds calculated at 9,700 km/h, this doesn't strike me as all as a place to live. Maybe there is a group or individual out there desperate enough to make a go of it.

Compared to the environment the SunMiners inhabit, this is a relatively clement location. Plenty of sunlight for power, and a range of gases including silicate vapour that could be harvested using sufficiently robust equipment. If there is carbon present that could be harvested it could be used to create permanent structures in orbit.

[AmrlKJaneway]

I just read about this place at my local science news source.

I can't wait to see what you guys do with it!

It certainly must be rare? A planet like this? May invoke some people to live in orbit of it, and escape to the surface (with plenty of protection, of course) as some form of relaxation/meditation. Nothing but you, your bubble, and the pounding sound of glass hurling into the walls surrounding you...

[stevebowers]

Not really. Silicate clouds are expected to be quite common in hot jupiters (hyperthermaljovians, in OA nomenclature).
Planets with Sudarsky class V characteristics
http://en.wikipedia.org/wiki/Sudarsky_ex...ate_clouds
would have silicate clouds and silicate rain.

The colour of a class V planet is expected to be blue
http://en.wikipedia.org/wiki/File:Celest...class5.png


However I note that HD 189733 b is supposed to be a Sudarsky class IV, which are supposed to be dull maroonish-brown; obviously there is a certain amount of overlap between the classes...

[stevebowers]

I think that the answer might be that these worlds are tidally-locked, so they have hotspots at the epistellar point; this location must be hot enough to form silicate clouds.