Re: Outer limits of solar system
Posted: 28.06.2013, 19:47
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argelesmer wrote:Yes the sun moves across the Milky Way, but all the stars move and
we never observed this phenomena around nearby stars ...
what does that lead scientists to believe that the sun is different ?
The heliosphere is hard to observe because it is a tenuous and dim objects. We do not observe the winds of most nearby stars because they are weak and dim to begin with, like that of Sun, and they are so dim at the interstellar distances that they are too dim to observe at all. There are some exceptions, like Mira Ceti, whose powerful outflows were recently found to have left a huge tail.
If Sun were stationary relative to interstellar gas, then Sun would indeed be continuously blowing up a perpetually expanding bubble.
However, if interstellar gas flowed relative to Sun then the flow would blow away the solar wind as it expands and weakens.
The current observations suggest that interstellar gas does move relative to Sun, and blows away heliosphere. However, a recent observational surprise was absence of bow shock - it seems that the speed of Sun relative to interstellar gas is slower than speed of sound in interstellar gas.
