first time telescope has detected a ground-water in the atmosphere of an exoplanet. For this discovery, much detective work was needed. Only with the creativity of it, astronomers have not so. From Guido Meyer
a long time to give astronomers with the mere existence exosolarer planet – that is, planets outside our solar system – no longer satisfied. Meanwhile, scientists are packed by the ambition to determine the composition of these distant worlds – and from as from the earth. At the annual meeting of the Royal Astronomical Society in Scotland, a team of European researchers on Friday will report a first: the first time it has demonstrated a ground-based telescope with water in the atmosphere of an exoplanet
In the description of What and Where in the cosmos, but it is increasingly confusing. A sensational headline like “water on Mars” can not be inferred from the observations.
reason is brittle imagination of scientists. Because astronomers really do not have excessive creativity when it comes to naming celestial bodies other solar systems: you simply numbered. So emblazoned 63 light years from Earth in the constellation of fox, a star named “HD 189733″ in the firmament. He is just visible in the northern hemisphere with the naked eye. And since 2005, astronomers know that this star has at least one companion: HD 189733b
Anything other than Earth-like
This planet is less than five million kilometers from its star, only about a tenth of the distance of the innermost planet Mercury to the Sun. The temperatures on the surface thereof are more than a thousand degrees. So he is anything but Earth-like and rather corresponds to Jupiter. Due to the strong attraction of the nearby star that the planet the sun has always the same page.
For the proof of this object almost eight years ago by the European astronomy satellite “Hipparcos” helped the so-called transit method. The planet moves on a regular basis – from the earth or from the “Hipparcos” satellites of view – just before his passing star
In each round a tiny fraction of the star’s light is swallowed by the minimal cover of the passing planet. This change in brightness can be measured – and in turn calculated from their orbit, size and mass of the planet, causing the drop in brightness
The astronomer Jayne Birkby from the Dutch Leiden University has viewed this inhospitable world closer – and not from the eyes of a space telescope, but from the earth. More precisely, of the Chilean Andes. From there, namely the European Very Large Telescope (VLT) looks far into the depths of space.
five hours it has his sights on the hot exoplanets and observed him on his path around its star that it orbits once in just over two days, and that at a pace of more than 400,000 kilometers per hour. “While we have been following this dance of the planet around its star, its spectral lines we have analyzed,” said the British astronomer.
specifically looked for her team after the signature of water molecules in the atmosphere of the planet. Because these leave an individual fingerprint in the spectrum. “It was a little like detective work,” said Jayne Birkby. But was successful – not only for H 2 O, but also for carbon monoxide (CO), which had previously been detected in the planet’s atmosphere, the researchers
case of water – here in the form of water vapor – is, however, a more complex molecule that could never be detected from the ground in the atmosphere of an exoplanet. “We have both molecules, the same method applied and were surprised that it worked well in the water,” said Birkby recalls.
For earthbound telescopes look at first once the terrestrial atmosphere in which there is also water vapor. And so the researchers had to look carefully to distinguish whether they capture the spectrum of the ground water or exosolaren planet whose spectral lines had come from space to Earth. When the detection of carbon monoxide, however, was more easily, as it occurs in the atmosphere, to a lesser extent.
This technique has thus proved now for carbon monoxide and water. “We now want to extend it to other molecules, so that we can determine the overall chemical structure of these atmospheres at the end,” said the astronomer from the Dutch Leiden future research intentions of their team. Carbon dioxide and methane, the researchers want to prove next on HD 189733b – ie compounds which are themselves either as organic or are excreted as waste products of organisms
with the space telescopes “Hubble” and “sharpener” the detection of methane and water on this planet was succeeded several years ago. “The significance of this discovery is the first experimental demonstration of these molecules directly from Earth,” said Robert Massey of the Royal Astronomical Society in London. “Hubble” and “Spitzer” are expensive instruments. “If we could also do with telescopes on the ground in future such fine observations, we could quickly and relatively inexpensively investigate relatively many stars at once,” said the British astronomer.
Massey evaluates these new findings though as a breakthrough in the investigation exosolarer planet from Earth, it sees but only as an intermediate step. Ultimately it related to something else: “Such a world we call ‘hot Jupiter’”. This planet is so out of gas, like Jupiter, is just much closer to its star and so much hotter. It is quite unlikely that there is any kind of life there.
“But we were able to demonstrate for the first time the principle that we can prove exosolarer of water in the atmospheres of planets from Earth,” said Massey. We are now ready to repeat this principle in smaller, Earth-like planets and detect water in their atmospheres. “That would be a huge step forward!”
Holy Grail of Astrobiology
If astronomers actually find Earth-like planet with an atmosphere which also organic compounds such as methane, water, oxygen and carbon compounds could be detected, which would be something like the holy grail of Astrobiology.
While this still would not be evidence for life on such a celestial body. Conversely, however, it would be highly unusual if output under such conditions, no life would have developed. The significance of so-called biosignatures – that gases or their waste products, which definitely could not be created on an inorganic way – are still controversial among scientists. The shows about the methane on Mars, which was regarded as irrefutable proof of the existence of organisms long. But these were – but not found on the red planet so far
– in contrast to methane.
And so the astronomer Jayne Birkby of the University of Leiden dampens hopes still. It is only once such planets would be discovered before it could go to the study of their atmospheres. “We need much larger telescopes that can capture much more light.”
A problem that could soon solve itself: Currently in the Chilean Andes gives the successor of the Very Large Telescope, the European Extremely Large Telescope. It will begin its work in eight years and then may characterize terrestrial planets.