Stellar Collision

[Tharghana]

What would happen if two stars collided?

[ajtribick]

The results seem to be fairly spectacular...

V838 Monocerotis might be an example of a merger of two main-sequence stars. The resultant eruption produces very pretty light echoes when it lights up surrounding nebulosity.

If the stars in question are white dwarfs and the total mass exceeds the Chandrasekhar limit, you get an overluminous type Ia supernova explosion (an example may be Supernova 2006gz).

[selden]

Collisions between stars happen frequently in the crowded centers of globular clusters. The results are known as "blue stragglers."

[Tharghana]

So anything near the collision would be destroyed?

[selden]

Tharghana,

You'll have to define what you mean by "near" and what you mean by "destroyed".

If either of the stars has a planetary system, the planets' orbits will certainly be disturbed by the gravitational effects of the other star, but they won't necessarily be ejected.

Very few (but not none!) of the stars in a globular cluster are likely have planets: the member stars have many close encounters whenever they're near the cluster's center, which are sure to disturb planetary orbits. It's known not to be none, because planets have been detected around pulsars in located in globular clusters. Pulsars/neutron stars are usually formed from supernovae.

[ajtribick]

If the post-collision object balloons up into a supergiant (a "mergeburst" event such as V838 Monocerotis), an orbiting planet could get engulfed. The large increase in luminosity would toast the system quite thoroughly.

Even if this does not happen, the planetary orbits would get disturbed, which could lead to the system becoming unstable.

Whether you'd have orbiting planets is another matter - the most likely places to have stellar collisions are in dense stellar environments such as globular clusters or star-forming regions (V838 Monocerotis is a very young system - these stars may not have managed to form planets yet).

[Chuft-Captain]

It's worth noting that the chances of two stars actually colliding is pretty slim.

In fact, as I understand it, when the galaxies Andromeda and the Milky Way eventually collide, although the gravitational effects on both will be quite spectacular and catastrophic to their structure, it's very unlikely that any of the millions (edit: hundreds of billions) of stars involved will actually collide with each other. (Sorry, can't remember the source) EDIT... googled it: http://www.haydenplanetarium.org/resour ... 01andmilwy

Just goes to show how much empty space lies between stars!

[Hungry4info]

V838 Monocerotis is a very young system - these stars may not have managed to form planets yet.

TW Hydrae b seems to suggest that planets can form much earlier than we thought.

[MKruer]

Someone asked the same question in this thread
http://celestiaproject.net/forum/viewtopic.php?t=11571

[Hungry4info]

Someone asked the same question

People have a habit of asking questions that have already been answered or discussed, however I don't think it's their fault. It's not human nature to search a forum before asking a question.

On the Yahoo! Answers forum thing, hundreds of times has the question "Have we really been to the moon?" been asked, the same thing with "Why is the sky blue" and "Are there really aliens" and "Why is Pluto no longer a planet?" and a really popular one, "Do you believe the 2012 prophecy?"

And people blame me for being antisocial

[MKruer]

Q: Have we really been to the moon?
Nope, but it is really made out of cheese according to google.

Q: Why is the sky blue?
Because if it was not blue it would be red.

Q: Are there really aliens?
Only of the illegal variety

Q: Why is Pluto no longer a planet?
There are no planets, only huge chunks of rock with gas floating around.

Q: Do you believe the 2012 prophecy?
Yep, December 21, 2012 those illegal space aliens will open a huge dimensional portal and destroy our not-a-planet planet, which will turn or blue sky red and fling people to the moon that we have not visited?€¦ ever.

[Tharghana]

When I mean collision, I mean two moving stars making physical contact, even if this is not possible, what would happen? Nothing? Chaos? If one of the stars had a planetary system would happen to them?

[MKruer]

In shot, to like stars would absorb each other, essentially doubling the mass. Some stellar material would be ejected but by far the majority would join into a new refreshed star. For the most part this should work with any main sequence star.

If it is a white dwarf on the other hand, the white dwarf would plow through the main sequence with very little resistance do to the huge differences in density. This would cause the main sequence star to collapse and then explode. The white dwarf would just continue on its merry way.

[Tharghana]

Cool. Can there be a Blue dwarf? Or is this not possible.

[MKruer]

Granted that everything on the main sequence is classified a dwarf star, yes, but a blue dwarf is vastly different then a red dwarf in both size and mass. A blue dwarf, is roughly 400% larger then our sun but it also as 7 times the mass.
You might want to read up on it at wikipedia
http://en.wikipedia.org/wiki/Main_sequence_star

[Hungry4info]

Tharghana, there exists a type of close binary called a contact binary. Two stars that orbit very close together can cause the photospheres of the other to beocme extended towards the other star. The result is two stars that are in contact.

[Tharghana]

Should tuch up on my star terminology, I mean a Blue star that is smaller then the sun? Is that possible?

[MKruer]

Should tuch up on my star terminology, I mean a Blue star that is smaller then the sun? Is that possible?

In that case, the answer is no. Though you can have a white dwarf the emits spectra that could be thought of as blue, the star itself would still be classified as a white dwarf. (it would also be the size of the earth)

[BobHegwood]

Tharghana, there exists a type of close binary called a contact binary. Two stars that orbit very close together can cause the photospheres of the other to beocme extended towards the other star. The result is two stars that are in contact.

Pardon the interruption from the Brain-Dead, but how is such a
thing possible?

Do you mean to say that these two stars orbit each other at such
a pace that a merge and/or explosion does NOT occur?

How can this be? I'll have a search for contact binaries, but I simply
was not aware that this was possible.

Thanks for the information, Bob

[MKruer]

I guess so, I would have though that if they did exist, they would not last long, but apparently (according to Google) 1% of all binary are contact.

http://en.wikipedia.org/wiki/W_Ursae_Majoris_variables