We will present some of this data here with the aim of using it as a tool to present basic questions that will serve as a basis for future insights for more in-depth studies
Mazar Haim
In the April 1996 issue of the journal Astronomy, an enlightening article was published about the discoveries of planets outside the solar system. Jupiter-sized planets have been discovered orbiting the stars 47 Ursae Majoris, 70 Virginis, 51 Pegasi and since then 80 extraterrestrial planets have been discovered. From the beginning the research was aimed at these targets, since their characteristics are similar to those of our sun. The data for these planets is only preliminary. We will present some of this data here with the aim of using it as a tool for presenting basic questions that will serve as a basis for future insights for more in-depth studies.
Planet Mass (Jupiter's mass is considered 1- mass) Diameter (Jupiter's diameter is considered 1- diameter) Distance from the Sun (in aster units) Time of revolution
Temp in oC
51 Pegasi B 0.6 0.32-1.35 0.05 4.2 (day) 1000
70 Virginis B 8.1 0.32-1.05 0.43 116.7 (day) 85
47 Ursae Majoris B 3.5 0.35-1.1 2.1 3 years 80
The currently accepted assumption about Jupiter is that it has a solid core with a diameter of 20,000 km whose mass is equal to 13 Earth masses and the density of matter is 20GR/CM3. The mass of these planets is known, their diameter is estimated to be between 1/3 Jupiter radius and slightly more than one Jupiter radius. From this, we can reasonably assume the following conclusions:
I. The core of 51 Pegasi B is less dense than that of Jupiter.
II. The nuclei of 70 Virginis B and 47 Ursae Majoris are denser than that of Jupiter. It seems that the gap in densities is orders of magnitude. The difference between the minimum diameter and the maximum diameter is in a ratio of almost 1:3. If we start from the assumption that there is symmetry between the internal structure of Jupiter and the internal structure of these planets, then the nuclear mass of 70 Virginis B is 8.1 times greater than that of Jupiter and the nuclear mass of 47 Ursae Majoris B is 3.5 times greater than that of Jupiter, and then the following findings are obtained:
The material density in 70 Virginis B can be GR/CM3 170.1 in the maximum diameter or GR/CM3 558 in the minimum diameter. In 47 Ursae Majoris B the density of the material in the maximum diameter is GR/CM3 77 and in the minimum diameter GR/CM3 242. In the case of 51 Pegasi B the density will be in any case less than that of Jupiter since its mass is less than that of Jupiter. Such a high material density in the first two cases is significant in terms of the chemical and physical processes occurring in the cores of these planets. It is assumed that these densities also have significance in terms of their axial rotation speed. An obvious question is whether these speeds are as high as in the case of the gaseous planets in our solar system?
III. The structure of our solar system is such that the terrestrial and high-density planets are closest to the sun, while the gaseous and low-density planets are further away. And here we find gaseous planets near their sun. The planet 51 Pegasi B is closer to its sun than the planet Mercury. Mercury is 0.387 astronomical units from the Sun, which is 57.9 million km. 51 Pegasi B is distant from its sun 0.05 AU which is only 7.5 million km. That is, 7.72 times closer to the Sun than Mercury. The question that arises here is the following: it is possible that if Jupiter was closer to the Sun like 51 Pegasi B it would have lost its atmosphere, if not all of it, then at least part of it due to the great heat of the Sun that would have evaporated it. The planet 70 Virginis B is a little further from the Sun than Mercury, so it is possible that its massive gravity can "balance" the wall of the Sun and prevent the escape of the atmosphere. The same goes for 47 Ursae Majoris B which is farther from the Sun. What then holds the atmosphere of 51 Pegasi B? A wall of the outer layer gives more validity to this question. Other pertinent questions: Is it possible that the great proximity of 51 Pegasi B causes it to always show one side of its face to the sun, and if so, what does this mean for heat transfer from the light side to the dark side?
If these planets have their own moons, these moons like the moons in our solar system only face these planets on one side. Whether or not they have atmospheres is hard to tell today. On the other hand, one can assume something about the effect of temperature drops between their day and night. The closer the planet is to the sun, the greater the temperature drops between day and night. At Mercury, the temperature in the "middle of the day" reaches 327oC - and in the "middle of the night" it drops to 173oC. On an Earth-sized body orbiting 51 Pegasi B the temperature range would be even greater and it is hard to believe it could hold an atmosphere. On moons orbiting 70 Virginis B and 47 Ursae Majoris B there is a greater probability of the presence of atmospheres.
An attempt to solve these questions will be inherently speculative in nature. The best way to deal with them is to build computer models, while presenting different data referring both to different physical sizes and to atmospheres with different gaseous compositions. These visible worlds will give researchers tools to deal with new information that will come from these planets in the future through various observational technologies that will be developed for these needs.
Sources
1. Robert Naye - "New Solar Systems" Astronomy, April 1996, pp. 50-55.
