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Print 6 comment(s) - last by Samus.. on Jun 25 at 9:16 AM

You'll need more than a cellar to wait out this storm.

HD209458b may not sound familiar to the layman, but many astronomers know it well. HD209458b, also known as Osiris, is one of the earliest extra-solar planets, or exoplanets, to have been found. The gas giant fits a category of exoplanets called hot Jupiters. These planets are gas giants, similar in size and mass to Jupiter, but orbit far closer to their parent stars.

Though Osiris is only .69 Jupiter masses, it is more than 250% as large as Jupiter. This puffed up atmosphere is likely a combination of the great heat and enormous tidal forces of the planet orbiting at .045AU. An Astronomical Unit is the mean distance of Earth from the Sun during its orbit -- a bit under 150M kilometers. For comparison, Mercury orbits the Sun at a mean distance of .39AU.

Osiris has been a much-studied planetary body since its discovery and it represents many milestones for the astronomical community. It was the first discovered transiting exoplanet, first proven to have an atmosphere, first shown to have an atmosphere composed of oxygen and carbon with evaporating hydrogen, and one of two planets first observed by spectroscopy. Later, observations would lead some astronomers to believe the planet's atmosphere also contains water vapor.

Now, using the European Southern Observatory's Very Large Telescope, a group of astronomers from MIT and the Netherlands Institute for Space Research at Leiden University have witnessed not only the first exoplanet weather, but the first measured orbital velocity of Osiris, providing necessary data to determine precisely its mass.

Osiris orbits its star, affectionately know as HD209458, in the same way the Moon orbits Earth. The amount of time it takes the planet to make one complete rotation is the same as the time it takes to make one complete orbit -- about 3.5 days in Osiris's case. The planet shows the same face to HD209458 no matter where it is in its orbital cycle. This invigorates the sunny side of the planet to temperatures in excess of 1,000 degrees Celsius. The dark side remains much cooler, and that temperature difference drives a storm of incredible magnitude.

Using the CRIRES spectrograph, an instrument on the VLT, astronomers very accurately measured the speed of carbon monoxide gas streaming from the hot side of the planet to the cool side. The heat-driven winds clocked in between 5,000 and 10,000 kilometers per hour. For perspective, the fastest non-experimental jet-powered aircraft in the world is the SR-71 Blackbird, which officially topped out at 3,326.6 km/h; EF5 tornadoes, the most powerful ever observed, can rip concrete and steel structures apart and significantly damage even the most durable skyscraper structures with wind speeds only slightly above 320 km/h.

Further, the powerful CRIRES made it possible to examine the carbon content of Osiris's atmosphere. The results showed that the atmosphere was high in carbon, similar to Saturn and Jupiter. This could indicate that, though Osiris is much closer to its star, it formed in a similar manner to the two local gas giants.

Such precise measurements of exoplanetary atmospheres could help planetary scientists understand how some of our own Solar System's planets formed as well as find telltale signs of familiar life in the atmospheres of future exoplanets that aren't so unforgiving.



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the more, the better
By kattanna on 6/24/2010 12:05:16 PM , Rating: 4
the more planets we continue to find and be able to study, the better our understanding of things cosmic wise.

its an exciting time for astronomy.




RE: the more, the better
By MrBlastman on 6/24/2010 1:32:09 PM , Rating: 2
I find it fascinating that the winds are 5000-10000 kph, yet the surface temperature on the lit side are only 1000 degrees celsius. I'm really curious about what class of star it orbits. At only .045 AU's, the amount of wattage hitting that planet must be astonishing.

After doing some further digging, I found that the planet is theorized to reach 2200/+/-260 degrees Kelvin on the sunny side, almost twice or more what I see here in the DT article. I also found that this planets star is very similar to our sun, being Type-G main sequence yellow dwarf star.

Mercury reaches about 700 K on the surface and it is 10 times further out, so perhaps the 2200 degrees is a bit of an understatement. I also wonder with it being in such a close proximity to its sun, this gas giant could potentially be more egg-shaped at the equator slightly convoluted due to the gravitational forces of the star upon its gases due to its closer proximity. Sort of a gravitational tug-of-war, which, when thinking about it, most probably is a contributing factor towards the huge windspeeds as the wind crests the apex of the bulge and then is propelled back around the planet.

I highly doubt that the planet is perfectly spherical being so close to the star. I wouldn't want to go vacation there, that's for sure. :)


RE: the more, the better
By marsbound2024 on 6/24/2010 3:24:19 PM , Rating: 2
Thankfully we have the Kepler Space Observatory monitoring the skies. With its most recent findings--which have to be analyzed first--we might very soon double or almost triple the number of exoplanets known. This in only a couple of months of data retrieval.

Now if only we could get the Space Interferometry Mission and perhaps even the Terrestrial Planet Finder concepts going... Promising mission concepts seem to always be delayed or cut altogether.


RE: the more, the better
By Samus on 6/25/2010 9:16:20 AM , Rating: 2
If they start drilling Alaska and have an oil spill there wiping out that seafood supply, too, I'm gonna jump ship for another planet. I just hope we find a suitable planet before we completely destroy this one.


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