Could the solar system formed in the distant star cluster?

Oct

6

2014

It is possible that our own house is in a giant star cluster, a cluster called Messier 67, a collection of suns and stars residues, about 2,700 light-years. Also, it is possible that more than a hundred stars there are striking similarities to our own. Astronomers searched for clusters of stars in our galaxy, the members of which approximately similar to our sun in elemental composition and age.

In January of this year, astronomers using the hunter HARPS planets in Chile, along with other telescopes around the world, found three planets of the stars in the cluster Messier 67. Although more than a thousand planets outside of our system have already received confirmation, only a small handful has been found in star cluster. It is also noteworthy that one of the new exoplanet orbits a star that is extremely similar to the sun – virtually identical in all respects.

Planets orbiting stars outside our solar system, have become common. They circle around stars of different ages and chemical compositions, scattered across the sky. But as we have noted, until now only a few planets have been found inside a star cluster. This is particularly strange because most of the stars were born exactly in such clusters. Astronomers are trying to figure out what could be so secret in the formation of planets in stellar clusters, which would explain the strange poverty.

Star clusters are of two basic types. Open clusters are groups of stars that formed together from the same cloud of gas and dust in the recent past. Most often they are found in the spiral arms of galaxies like the Milky Way. Globular clusters contain more spherical collections of older stars that orbit the center of the galaxy. Despite a careful search, in globular clusters were detected planets and at least six – in open clusters. Exoplanets have also been found in the last two years in the clusters NGC 6811 and Messier 44, and another was found in the Hyades cluster.

Anna Brukalassi (Institute for Extraterrestrial Physics, Max Planck in Germany), lead author of the current study, wants to learn more.

“In the star cluster Messier 67 almost all the stars of the same age and composition as the Sun. This makes the cluster an ideal laboratory for studying how planets formed in such a dense medium, and they are produced mostly in massive or less massive stars. ”

The team used the tool to search for planets HARPS on the 3.6-meter telescope at the observatory HARPS La Silla. These results were complemented by observations of several other observatories around the world. Scientists have carefully studied the 88 selected stars in Messier 67 in six years, trying to detect the presence of planets in orbit. Many of the star clusters do not differ intense brightness that is acceptable to the search for extrasolar planets, so an attempt to detect a weak signal from such a planet to its limits HARPS.

Were discovered three planets, two of which revolved around the sun-like stars, and one – around a red giant. The first two planets by weight were about a third of Jupiter and turned around native stars in five and seven days, respectively. The third planet orbiting the star in 122 days and a mass greater than Jupiter.

The first planet was orbiting notable star – one of the closest analogues of solar twins, identified so far. This is the first solar twin in the cluster, which turned out to be a planet. Solar twins solar analogs and solar-type stars – stars are categories according to their similarity with our luminary. Solar twins have similar mass, temperature, and chemical properties. Solar twins are very rare, while others are more common categories.

Two of the three planets – the “hot Jupiters”, which are comparable to Jupiter in size, but are much closer to their parent stars, and hence hot. All three are closer to their stars than is necessary for the existence of liquid water.

“The new results show that the planets in stellar clusters is about as common as around single stars – but they are not easy to detect. The new results differ from previous studies, in which the search for planets in clusters is not successful, but in many ways consistent with later observations. ”

If you go back to the open-ended question about what the star could be born with a limited region of our galaxy, the search for an answer to this question is limited by our accuracy in the measurement of such huge distances and specific motions of the stars, as well as by the number of objects on the basis of which is searched . Recent computer simulations of motions of stars in Messier 67 shows the calculated trajectory in which our solar system had to be ejected from the star cluster, but it turned out that for this to happen is very rare alignment of at least two or three massive stars in this cluster. In addition, the tidal forces from such a release would have to cut our planetary system.

Nevertheless, scientists are more inclined to believe that it just happened. If these changes occurred over billions of years, it is possible that Messier 67 has thrown the solar system less dramatic fashion. Further studies will show, but now we can doubt that we are in a certain kind of “orphan works”.

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