According to a team of researchers from the California Institute of Technology, the characteristics of four exotic exoplanets have been pinned down in unprecedented detail. This was done using a new high-tech gadget, perhaps ushering in a new age in exoplanet discovery.

 

The planets, which have roughly the same mass as ten Jupiter-sized bodies, orbit a star known as HR 8799, which lies a mere 128 light-years from our solar system. The star is about 1.6 times the mass of our sun and about five times brighter -- releasing more than 1,000 times more ultraviolet light than the sun. In the past, astronomers directly imaged the four planets, but since the light emitted from their parent star is typically tens of thousands of times brighter than the starlight that reflects through the atmosphere of the planets, differentiating between the the star and planet (and ultimately taking the spectra of the planet's starlight to reveal its composition) was quite difficult.

 

Ben R. Oppenheimer, an astronomer at the American Museum of Natural History, likened it to taking a single image of the Empire State Building from an airplane that reveals the true height of the building AND a bump on the sidewalk next to it that is as high as a couple small bacteria.

However, the new technologies (entitled Project 1640), which made the discovery of the characteristics of the planets possible, is a series of first-of-their-kind instruments aboard the Hale Telescope. This telescope is equipped with a state of the art imaging system that can discover planets that are typically drowned out by the overwhelmingly bright light of their parent star. Ordinarily, the process of detection (and confirmation) is quite a tedious task for planet hunters, as the planets in question must be transiting the star relative to our vantage point, obstructing a very small amount of starlight. After the discovery, many subsequent hours of observations must be made before the existence of the potential planets are verified -- time that is scarce as far as our telescopes are concerned. This new process allows astronomers to observe many planets at one time, instead of having to take measurements of each planet in the system one-by-one.

 

It does this with the cooperation of four separate instruments, which include:

 

- an adaptive-optics system, used to make millions of adjustments to two six inch mirrors installed on board the device each second.
- A corona-graph that is used to dim the light emitted from the star, instead of the light reflected from the planet.
- A specialized wavefront sensor that helps filter out background starlight.
- An imagine spectrograph that can take 30 images simultaneously at many different wavelengths.

 

One of the planets orbiting HR 8799 (CREDIT: Dunlap Institute for Astronomy & Astrophysics; Mediafarm)

Using this method, the team was able to study the planets orbiting HR 8799, which are about the same distance from their parent star as the gas giants in our solar system are from our sun . This kind of imagine is something that has never been done to this extent before, as most of the exoplanets we've discovered have been orbiting at only a fraction of the distance that separates Mercury from the sun. And they found that a few surprises. One of which, is that the planets emit light at longer wavelengths than other celestial objects that are of similar temperatures, perhaps eluding to the existence of patchy clouds in the upper atmospheres.

 

They were also quite surprised by the spectral diversity of each of the planets.Typically, ammonia and methane are mutually inclusive, with the exception of planets that thrive in very cold or blistering hot temperatures. Unexpectedly, this was not the case. None of the planets contained both chemicals, only one or the other. This was further compounded by the fact that the temperatures on the planets generally hang around "lukewarm" temperatures approaching 1,000 Kelvin (about 1,340 degrees F), with traces of chemicals like acetylene and carbon dioxide in their atmospheres.

 

The team plan to collect even more data on this system, in addition to surveying more than 200 stars that are located within 150 light-years from our solar system. Considering the fact that the tools can observe celestial objects that are 1 million to ten million times more faint than the light from their parent star (using only an hour worth of observations), we should expect some interesting finds in the coming months.


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