“Lonely planets”

Astronomers discover a new kind of planet: lonely hikers who stretch away from each sun away from each sun. There are apparently a whole lot

That sky researchers find new planets, has become almost every day. Since 1995 you have found about 500 exoplanets. In the habe, as the search methods have been refined from year to year, the detection limit has also fallen: today you have been able to hunt for any objest sky corporations that were modeled for the solar system. You can rarely rely on the direct observation. When searching is therefore a selection of different technologies for use, which are aimed at a specific property of the object and its star system.

Artistic representation of the exoplanets corot-9b passing past its sun. Image: ESO / L. Calcada. OFF: the discovery of the exoplanote corot-9b with the harps spectrograph of the ESO

There are first the so-called radial speed method. It is based on the fact that even a fairly small object – the planet – on its gravity on its huge neighbors – the star – works. It is enough to observe the coarse object to shut out of its web distortion on the small companion.

The wankel-bahn can be recognized by a doppler shift of the star spectrum that can be detected by the earth from the earth. The more detailed both objects, the visible and the invisible, are, the better this method works. At a small star (also the sun is also the sun) you will find so also earthly planets.

The transit method

The transit method, which is currently the best chances for discovery of really small planets, is based on a principle that people have been observing in the sky for years of age: the darkening of an object by another, how it practicing moon, earth and sun regularly. Of course, we see this dark only if we look from the side to the railway level of the covering object. But thanks to the many stars in space you just have to set up more observations in order to make a find at some point in this way.


Similar applies to the method of microlensing. The name actually explains the principle quite well: it is based on the fact that the gravity of a heavy object can serve as a lens for the radiation of another object in its background. Who owns a photocamera, however, however, that a motive observed by a lens does not look automatically sharp: you have to bring motive, lens and sensor in the same level and in the right distance.

And so only one of one million stars of the central milk strain is increased at a certain point in time by such a meeting of chendable events, as the astronomer joachim wambsganss writes in a post in the science magazine nature. And even if each of these stars had a jupiter-inciting companion, one could actually discover only one percent of these planets due to inappropriate geometric conditions. Since astronomers can not turn their lenses, the stars, they can only be overcome, just to look for themselves and trust their gluck.

This is exactly where two international research teams have been concerned for a few years. Because the microlensing process offers two advantages: there is a good statistical overview of the components of the universe, and it is also suitable to locate quite small planets. In nature, the researchers now report on the results of their work. For example, the moa team (microlensing observations in astrophysics) have succeeded in checking 50 million stars of the milky strait over two years at least once an hour. The researchers once again discovered 474 microlensing events, of which ten were more short than two days.

Results cosmic billiards

The short the event, the smaller the lens – for less than two days the researchers ame that the lenses had planetary, not staring. The scientists compared their data with those of the OHLE team (optical gravitational lensing experiment) – seven of events were also noticed at OGLE. Since there were no periodicity, the researchers ame that it must be at least very far from their guest-star-distant planets – probably also those who alone by all hiking.

But interesting is also the statistical analysis: it shows that such planets have to be far more perceive than they previously accepted. There should be more of it in the milk strain than there are stars of the main series.

How have the lonely hikers broken up to their journey? The researchers suspect that this could be the results of cosmic billiards. In systems and protoplanetary discs with several coarse corpers, it can easily come to the fact that on the one hand gas giants get into size close to their hometer, but on the other hand, their brother can be thrown out of the system.

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