how big an impactor

How big would an impactor have to be to destroy a star relative to it's size. 10%? 25%?.... I have often wondered that, as our sun is 95%+ of our solar system mass, it must exert enormous gravity on bodies getting to close. How big would an impactor be to upset it.....give it indigestion.? is there any evidence that this event is common throughout the Galaxy. and finally has our sun accreted in mass after initial formation.

signed
Declan
very preturbed, Co Laois

Hey Declan very good question.It would have to be an object with a lot of mass ie, white dwarf,black hole.Check out the following link (sorry to any non broadband users) and tell me is that CME a coincidence or did the two comets have anything to do with it ? because stellar physics would say they didn't.

sohowww.nascom.nasa.gov/gallery/Movies/C...E/C3_2comets_CME.mpg

I would also throw in another wobbler, in that would the impactor need to be a solid, or plasma-like in nature? For example, if an impactor was to be a smaller star, it would continually loose mass the close it got to the Sun, be it from gravitational attraction of matter (thus the Sun acquiring more), or the solar wind blowing off some in the opposite direction. If it was solid, then it's change in state would not be as drastic, and probably (most of it) survive the inner corona before impact.

As to the size of the impactor in each scenario, I wouldn't have a clue where to start.

Seanie.

An after thought: I recently gave a lecture which also highlighted some of Earth past "extinction event" impacts. The remains of what we have left - craters - suggest (from computer modelling) that the asteroid responsible is between 10% and 20% of the size of the crater left behind. At least for the ones above 50-60km in size. I am sure there is some proportion to the physics behind it too.

Seanie.

I suppose you are right Seanie about the phyisics. certainly impacts on Jupiter would probably not leave any lasting outward sign on account of no surface to scar.... on the other hand earths crust is fragile and will show long term evidence of impact not withstanding the effects of life and weathering. On the other hand a star would probaly not show any outward signs of impact due to smaller impactors evaporating before impact....but would they change the chemistry :


signed
Declan
Highly disturbed
Co Laois

The November 2002 Scientific American mag had an article entitled “If a White Dwarf Struck our Sun”.

The article describes the head on collision at typical interstellar speeds.

The Sun loses the encounter and is utterly destroyed.

The White Dwarf barely notices that it has hit anything.

To paraphrase the article:
“The sun blows itself apart in minutes. Meanwhile the white dwarf continues on its way as though nothing had happened....not that we would be around to complain about the injustice of it all”

Don Dixon’s cover painting in that issue captures the last moments of the Sun :

www.cosmographica.com/gallery/portfolio2...Collision_large.html

The white dwarf is approaching from the top left, it’s gravity bloating the sun into an egg shape.

The view is of the last sunset on....... “The Last Day”.