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Viewings: 5517The vast majority of known exoplanets found using various indirect methods, in particular Doppler and transit photometry. The method of direct visual detection with the help of telescopes does not produce such results, because the planet is extremely weak light sources (unlike stars), and their light is very difficult to "filter out" due to the high brightness of the parent star. Therefore, the direct detection of exoplanets is a very difficult task is only possible if a celestial body is large, and its orbit is removed from the stars that light the latter does not interfere with the observations). That is how it works: from 31 extrasolar planets, the open method of direct observation, the easiest twice-three times heavier than Jupiter, and the most close to its star is twice as far from it than the Earth is from the Sun. Well and the most distant and does is 2 500 and. E.
When the surface temperature of 600 To aktolun the size of the Earth can be detected with a probability of 5? (99,9995%). (Illustration M. A. Peters, E.Turner, David A.Hardy.)
Such gas giants are not very interesting to search for potential life. But other methods of direct observation is not to get it: always will be easier to notice korotkoperiodnye massive planet. Or not?
Mary Ann Peters (Princeton University) and Edwin L. Turner (University of Tokyo) had considered the option that seems so obvious that even unclear how it could not notice. Part of the satellites of the gas giants in our Solar system is exposed tidal heating up: the enormous gravity of the neighboring giants causes tidal movement of their surface layers, and the resulting friction leads to a significant heating. Under some assumptions, such tidal heating is responsible for the existence of a hypothetical subsurface ocean water even on Triton - remote at a huge distance from the Sun large satellite.
After spending a computer simulation of the effects of tidal heating for a wide range of initial conditions, the researchers found that heated so the satellite can have the luminosity more of the planet (!) and even up to 0.1% luminosity stars like red dwarf (spectral class M5)that uniquely allows you to filter its light from the radiation of light. However, the surface temperature of such heated satellites must be at least 600 To, and any kind of life here may not count (even the hardiest thermofilm nothing to do where more than 400). In addition, the radius of such aktywny should be equal to the earth, and the area is confident detection will be limited to 18 light years. And yet, despite the fact that in the Solar system there are no satellites diameter of the Earth, the probability of the existence of such bodies in other planetary systems can be quite high: for example, we do not have any "supersample" or larger planet Jupiter, however, according to astronomical observations, such planets in number almost dominate the Universe.
And yet a chance. Space telescope "James Webb" with composite mirror with a diameter of 6.5 meters (Hubble - 2.4 m), which by 2018 must be in orbit, according to the authors ' calculations, will allow to reveal tidal heated aktywny with a surface temperature of 300 K (which is almost equal to the temperature of the Earth's surface). Thus aktywny held on 12 and. that is, from their stars, will surely be detected at a distance of up to 15 light years from Earth, meaning we will be able to explore two dozen closest to the Sun to stars.
As they note, in the event of between one planet moons resonance their tidal interaction with large planets will be very long. As an example of such resonance (1:2:4) to specify IO, Europa and Ganymede, where he maintains a stable orbit eccentricity IO and, accordingly, tidal heating of this jupiterians satellite. By the way, the imposition of a system of satellites of Jupiter on Neptune (with appropriate scaling of the orbits of such satellites) revealed that the luminosity IO due to more intense heat would be higher than that of the Neptune. In other words, even in our system, we only by accident that do not observe such a super-bright satellites, the main source luminosity of which would be the tidal interaction.
"So what?" - perplexedly the reader will ask. Because aktywny you can search and indirect methods. Yes, this including deals telescope "Kepler", but so far without much success. Because of the low mass and radius indirect detection methods aktolun not as good as in the case of exoplanets. But the topic is very important. In fact, several studies 2010-2011 showed that in reality the number of aktolun, mass approaching the Earth, can be enormous. Strictly speaking, even less of azoluna can have a very dense atmosphere: the same Titanium is the density of the atmosphere exceeds the Earth, and this despite the gravity inferior to the moon. At the surface temperatures in the region of 300 To, they can be quite suitable for life. Given that the majority of known exoplanets - gas giants, the presence of even a small part of them such warms the tidal interaction of aktolun can mean so powerful the population that it can be numerically compare with the number of self-earth-planets.
A side result of the research were the following interesting conclusion: some exoplanets detected by direct observation, actually can be just such a preheated its giant neighbors-aktywami and not the individual planets. So, Fomalhaut b, exoplanet that I find about Fomalgaut, star of spectral class A4 25 light years from Earth, "close", demonstrates this difference in brightness and other settings that researchers see in him the first candidate to preheat the tidal interaction of aktolun (CVA).
This explanation will help to combine the data of observations in the optical and infrared range: small azoluna will not give significant infrared radiation, as a normal exoplanet (it just don't find when observations). On the other hand, Eclipse hypothetical aktywny have to change the radiation from the long-suffering Fomalhaut b that it will at all times to vary. Scientists believe that further regular monitoring system will provide us more complete information about the presence of CWA in the system of Fomalhaut.
The authors emphasize that according to the developed model, direct observation, and the appearance of images aktolun of this type (with liquid water on the surface) in the vicinity of the Sun will be technically possible before getting images of the surface normal of exoplanets in the habitable zone. In fact, we can do it in the coming years, without the implementation of such expensive projects, as Terrestrial Planet Finder and DARWIN.
Based on the arXiv.
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