Volcanos
Volcanoids (also Vulcanoids ) are hypothetical asteroids that could exist in a sparsely populated “third asteroid belt ” within the orbit of the planet Mercury .
Despite lengthy search programs, their existence has not yet been proven. For the time being, it arises solely from theoretical considerations about the stability of slightly eccentric orbits in the ecliptic between the Sun and Mercury. The fact that Mercury, the planet closest to the Sun , was exposed to intense bombardment by smaller celestial bodies in the early days of the solar system as a further indication .
properties
The volcanoes, if they exist, must be smaller than about 50 km in diameter, otherwise larger bodies would have been discovered with the solar probe Solar and Heliospheric Observatory (SOHO). So far, only a few asteroids have been found in this area on extremely eccentric orbital ellipses that only spend a few percent of their orbit within Mercury's orbit: (1566) Icarus (1949, 0.19–1.97 AU ) and the comet-like one from the IRAS space telescope in 1984 discovered (3200) Phaethon (0.14-2.40 AU).
Possible preferred orbital areas of volcanoes were calculated at 0.18 and 0.15 AU distances from the sun. Like the rings of Saturn or the asteroid belt, a volcanic belt would have to have Kirkwood gaps and concentrations.
search
Already about 100 years ago, the then "record holder" of discovered minor planets, the Bohemian-Austrian astronomer Johann Palisa , searched for Vulcanus , a hypothetical "intra-Mercury" , during an eclipse expedition to the South Seas . Although his search was unsuccessful, the small bodies were now given the analogous name.
From the surface of the earth, the discovery and observation of volcanoes are particularly difficult because of their proximity to the sun, because they can only be seen in the twilight range of the rising and setting sun. Alternatively, the area around the sun could be searched during a total solar eclipse. Large telescopes are unsuitable for such search programs, as the sensitive optics would be destroyed by the high light radiation after the risky end of the totality phase. The use of space telescopes is opposed to the high costs, which would be more responsible for the search for potentially collision -prone objects near the earth (NEO).
In the meantime, the search is intensified from the high-altitude aircraft in the infrared range , because it is to be expected that bodies in this vicinity of the sun are very hot and emit noticeable heat radiation. Surface temperatures of 700 K to 900 K are expected.
See also
- Asteroid belt
- Zodiacal light
- Near-Earth asteroid
- List of hypothetical celestial bodies in the solar system
- Vulkan (planet) , a hypothetical celestial body, which was postulated (up to the development of the general relativity theory by Einstein) to explain the peculiarities of the orbit of Mercury.