After the discovery of more solar systems

1987/04/01 Arregi Bengoa, Jesus Iturria: Elhuyar aldizkaria

• Astronomia

In addition to all the problems generated by the knowledge of our Solar System and the analysis of its components, this topic is always related to another question: whether or not there are more planetary systems like ours. But to find the answer, the question must be properly posed. It is essential to relate the birth of our Solar System to the birth process of the Sun as a star. Therefore, we must clarify that: If planets and other bodies revolving around the Sun are a consequence of chance or if, on the contrary, they are part of the same birth process.

The current situation of research leads us to support the second hypothesis. It is believed that stars are the end of the process of shrinking dust clouds that abound in galaxies. In principle the density of these clouds is very low and do not present an appreciable tendency of contraction. The process begins with the action of an external agent, such as the explosion of a nearby supernova or the shock waves that occur when crossing an arm of the galaxy. In the first phase of compression the cloud is divided, continuing with the compression of each part we will call protostar.

Beta Pictoris, a star not far from the imposing Canopus, is of the fourth magnitude of the constellation of the Painter. It is located at a distance of 55 years of light and, being a young star, less than a billion years old, has characteristics similar to the Sun. In 1983 he aroused the curiosity of astronomers. The IRAS satellite discovered a cloud matter around it. This cloud of materi is triple the radius of the Solar System. Is it a planetary system?

Shrinkage means an increase in turning speed, so the cloud deforms into a disk. Logically, most of the matter accumulates in the center, where the star is formed when the temperature reached inside due to compression is sufficient to produce thermonuclear reactions. Meanwhile, planets are formed outside the disc, due to the shock and stacking of the rocks present. Finally, the wind of the newly created star in the center expels all gases and other residues from the area.

If the process described correctly describes reality, planetary systems would not be due to chance, but to a normal process. This conviction is based on attempts made in recent years to highlight the existence of other solar systems. Although a positive result has not been achieved so far, researchers are optimistic about the future. Let's look at the steps taken and the projects in the short term.

Planetary detection techniques are not based on ordinary observations with a telescope. The light that planets can reflect is not enough to differentiate from their star mother by observations made from Earth. The evolutionary technique of these dark friends of visible stars, both planets and stars, was based on the gravitational influence that these bodies in principle have on the star.

The theory is simple: the tours that perform two bodies that move around baptism have their center in the center of masses. For this reason, stars with dark friends do not make a direct journey, and the amplitudes of the vibrations that would be observed would give us information of the bodies that surround us. However, despite the simplicity of the technique, measuring is a very difficult task, so interpretation has generated endless controversy.

The pioneer of the technique was the astronomer P. van de Kamp. In 1930 he began to make a photographic procession of nearby stars. The most disturbing star was Barnard: According to measurements made between 1938-63, the van star of Kamp rotated about 1.5 times a body of the mass of Jupiter. The result was more striking because a body of this mass should be a planet and not a star as expected at first (the mass of a body should be 0.05 from the Sun — 50 times from Jupiter — to produce thermonuclear reactions).

Astronomers soon began to analyze published data. It may be thought that the biggest problem in confirming this type of data was the time needed for data collection, but the work was rejected without any other comparison. When Harrington showed that data taken up to 1950 were not valuable. After a thorough analysis of the data, he discovered that all observed stars had very similar disturbances. This made him think that the operator could be a telescope.

After performing the appropriate tests, he discovered that in the year mentioned they had moved to correctly place the lenses of the telescopes. Despite the need to discard the data taken up until then, van de Kamp continued to work and in 1976 published a work in which the star Barnard had two planets. But the incident with the above questioned the credibility of van de Kamp and the community of astronomers took these results with great skepticism.

The problem was recovered three years ago after the analysis of satellite data launched by IRAS to study the sources of infrared rays. In addition to finding thousands of new sources, IRAS showed an infrared emission higher than the theoretically predicted in well-known stars such as Vega and Beta Pictoris. The only explanation astronomers could give to this demasia was based on the planets around them.

The idea is that planets capture a lot of energy from the star, most of them from a small wavelength emission. However, the reemission of this energy occurs in the infrared zone. Therefore, the infrared band is the best for the detection of planets, since the ratio of infrared emissions of stars and planets is much lower than in visible light. It is evident that, in the latter case, the light of the storm star totally what the planet can reflect.

Knowing the advantage of this new technique over van de Kamp, B. Smith and R. Terrile photographed Beta Pictoris by infrared. According to them, Beta Pictoris is surrounded by a materi disc, with a diameter of approximately 20 times that of the Solar System. In the center looks a dark. According to Terrile, the darkness is because the star's wind has expelled all the gases and powders from its surroundings. However, not all astronomers agree with this interpretation, and although data from other stars have been collected, the study is yet to be completed.

Next advance of observations made in the field of infrared, D. McCarthy has come hand in hand with McCarthy to take advantage of the influence of the atmosphere that a priori could be considered harmful. The name of the technique is near-infrared sludge interferometry and is based on the influence of atmospheric turbulence on the propagation of light. Due to these turbulence, the image of the star given to us by the telescope consists of about 1000 small fangos. Obtaining these interference spotlights can provide accurate information about the position of the star using photographs taken with a very short exposure time. This is what the Two-Tum-mied Toad II (TTT II) detector designed by McCarthy does. Its resolution is 0.01 arc points.

The use of TTT II has resulted from another star with friends, the star VB8. His friend, named VB8B, has an important particularity: his mass is 60 times that of Jupiter, so it cannot be said to be a star or planet. Some consider it an example of a brown star, that is, its formation would be equal to that of the star and not like that of the planets, but could not maintain thermonuclear reactions to illuminate them as stars. The rapid development of technology allows to improve all tools and design new ones.

As a last example, G. We will mention the Gatewood Multichanel Astrometric Photometer (MAP), made with fiber optics, photometers and more modern computers. This scientist uses the same technique as the vibratories used by van de Kamp, but the measurements are much more accurate (it has a resolution of 0.005 arcseconds) and it takes much less to have measures to obtain conclusions. To achieve this, use a transparent plate with very engraved black stripes. Moving the plate, the light of the star and his possible friend deviate differently obtaining the advantages mentioned.

To conclude we will say that all astronomers working on this problem agree on one point. To give a definite boost to research, telescopes must go out into space through satellites to avoid the influence of the atmosphere. G. According to Gatewood, his map would reach a resolution of 0.000001 under these conditions. McCarthy claims that the resolution of the VB8 star images would increase 100,000 times.

Specifically B. Harrington and his collaborators prepare the Hubble Space Telescope which will probably be put into orbit through the launcher in 1988. R. Terrile also believes that his corography may be in space in 1990. Finally, all astronomers are waiting for the launch of the Astrometric Telescope Facility (ATF). This tool, along with other experiments, would bring the PAC connected. Therefore, we can be optimistic and think that the problem can come into resolution shortly.