Strange world

Collision of planets has created a strange world

Two major planets have collided among themselves, forming a unified cosmic body. And it happened, according to stars measures, literally yesterday - a few tens thousand years ago. Astronomers rejoice to good luck: it seems, for the first time we can observe consequences of an accident so enormous.

So, we are acquainted with drama characters. A brown dwarf 2M1207 spectroscopic class M8 (it can be seen well with an aided eye in constellation of Centaur) and its small partner - a planet 2M1207b. This one has been tormenting scientists with riddles for some years now. And here now the newest examination has allowed to make a guess: the strange features of the given object are explained in that he is born as a result of absolutely recent collision of two planets. But first things first.

About this pair the mass-media have widely started talking in 2004. Then astronomers managed to find out for the first time in history not ony an exoplanet but also to receive an immediate photograph of a system, that is - the planet itself against the parental star. And that the lamp(2M1207) in this case was not a high-grade star, and only brown dwarf (which mass then have estimated as 25 masses of Jupiter), did not change anything.

In 2005 analysis of new pictures of sensational pair has proved that it is really a planetary system, instead of effect of only visual imposing of two space bodies distant from each other which have appeared almost on one beam of sight. If to judge on masses of objects, however, it would be possible to term system not planetary, but double. One object - a brown dwarf with mass in 25 Jupiters, and second - in 8.

However, in the end of 2005 astronomer Eric Mamajek from Harvard-Smithsonian Center for Astrophysics has erected, that 2M1207 is hardly more close to us, than was considered earlier.

The distance to this object has been determined as 172 light years (instead of former number - 228), accordingly observable objects had smaller, than scientists figured before, luminosity and their masses should be revised towards diminution. And now it is considered, that 2M1207A "weighs" as 21 Jupiter, and 2M1207b - as 5.

Recently these 172 light years have been confirmed by other methods of measurings, But only clearness concerning the nature of this "sweet couple" was not added. On the contrary, some strangenesses became even brighter. The temperature, luminosity, age and site 2M1207b do not coincide neither with any theory, nor with any representations about formation of planets at stars.

"It is so strange an object, that it requires strange explanation", - says Mamajek.

The matter is that the age of a brown dwarf 2M1207A makes all 8 million years. Its planet - not much younger. And on existing models the planet-giant of this age already should cool down to temperature below 1 thousand kelvins. However the temperature measured by astronomers 2M1207b makes approximately 1600 kelvins.

Now Eric Mamajek and Michael Meyer from University of Arizona have put forward the hypothesis which has explained these "superfluous" temperature.

Simply given cosmic space body has not had time to cool down after collision and merging of two planets which naturally have generated it. By calculations of scientists, 1600 kelvins should "dissipate" in space for 100 thousand years, and the temperature of this planet-giant would fall to value which is ordered by the theory. And it means, that collision of planets happened recently (in space measures).

If 2M1207A and its system would be much more senior (like the Sun and its planets), chance of concurrence of an epoch of fast cooling of that strange planet and our time would be absolutely illusive. We would observe 2M1207b already cold and would puzzle over its rule, the sizes and mass.

By the way talking about sizes and mass. Here are some troubles too. We will tell, being repelled from temperature of a surface and other measured parametres, astronomers have considered luminosity which this planet should have. However in eyepieces of telescopes it looks in 10 times more dullly predicted by models. Why?

In 2006 astronomers have put forward a hypothesis, that the brown dwarf is surrounded by the dust disk shading a planet-giant. And still, to co-ordinate all parametres of this double system, researchers have formulated a hypothesis about simultaneous formation 2M1207A and 2M1207b by seal of a material of a space cloud. How usually multiple stars are shaped.

Mamajek and Meyer have other explanation to a phenomenon of low luminosity of a planet. 2M1207b much less on the size, than it is considered now - researchers assert. They have calculated, that the radius of this giant makes 50 thousand kilometres (little bit "more modestly" than Saturn's). Therefore supposedly the planet shines feeblly - simply at it a surface area less, than astronomers earlier figured.

Repelling from value of typical medial density of planets-giants, authors of this work have totalled, that the mass of a phenomenal planet makes all a quarter of mass of Jupiter (or 80 masses of the Earth), instead of 3-5 and even 8 Jupiters as it was asserted in the previous examinations.

These conclusions are presented in the press release of centre for astrophysics, and it is possible to be acquainted with calculations of scientists in their article (PDF-document) in Astrophysical Journal more detailed.

It is necessary to tell, that in a pore of a youth of the Solar system rendezvous and collisions of planets were pretty much usual. About it speak the scattered worlds on its exterior boundaries.

To the same testifies the moon: the most popular and worked out hypothesis says that it has arisen at shock of a body in the size approximately about half of Mars or about Mars across the "newborn" Earth.