On Earth we have volcanic eruptions that can alter the climate, usually by sending up an extremely thin cloud of ash that is blown by the prevailing winds until it surrounds the world. Even spread so thin it affects the amount of light that reaches Earth's surface and can make winters everywhere a little colder for a couple years afterward. So we've established that such a cloud of ash could be spread almost transparently thin and still affect the climate.

What if a small planetoid hit the sun? Chemical bonds would be broken by the Sun's radiation, so only fundamental elements would survive, as ions, spread thinly around the Sun's upper layer. If it were a planet like Mercury, Venus, Earth, Mars, or Pluto that collided with the Sun then the primary elements of planetary material in order of decreasing parts-per-million might be as follows:

Oxygen
Silicon
Aluminum
Iron
Calcium
Sodium
Potassium
Magnesium
Titanium
[Hydrogen]
Phosphorus
Manganese
Carbon
Chlorine
Chromium
plus trace elements
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(Of course planetary hydrogen would just blend in with the Sun's hydrogen.)

If a thin haze of these materials formed a shell around the Sun, what would be the effect? If it caused a mini-ice age on Earth, then we might suppose that the Sun's radiation was somehow decreased or quenched at certain wavelengths by these materials. The total energy released by the Sun would undoubtedly remain unchanged, however these materials might absorb radiation from inside the shell, and re-emit the energy at different wavelengths -- Perhaps at wavelengths that cannot as easily penetrate the Earh's atmosphere?

"Solar radiation is not emitted in a smooth continuum. Superheated atoms in the Sun, particularly Hydrogen and Helium, absorb radiation in distinct wavelengths. These absorption bands are visible as dips in the green line in the graph above, which represents the spectrum of sunlight that arrives at the top of the Earth’s atmosphere. Additionally, gas molecules absorb radiation in the Earth’s atmosphere, further reducing the radiation at the surface. The blue line represents the spectrum of radiation arriving at the surface of the Earth on a clear day in the tropics, based on an atmospheric model. (Graph by Robert Simmon, based on model data from the NASA GSFC Laboratory for Atmospheres)"

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