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Padawan
2004-Apr-30, 01:55 PM
Would anyone know any binary system where the components orbit each other VERY closely? Also would you know their spectral class/colour?

ChesleyFan
2004-Apr-30, 01:58 PM
Try googling for "spectroscropic binary". These are stars too close to be split optically, so you have to watch for Doppler shifts in their spectrums instead.

Visual binaries can look very close, of course. The Double-Double in Lyra is a good example.

Padawan
2004-Apr-30, 02:08 PM
Oh yeah, why didnt i think of googling?

hehe, my brain is wasted today, hehehe.


Thanks man, i'll have a look ;)

rigel
2004-Apr-30, 02:20 PM
Aren't there a few where one star is literally eating another?

Padawan
2004-Apr-30, 02:26 PM
i'd sure like to have the name of that one, so i can do some reasearch on it ;)

Normandy6644
2004-Apr-30, 04:17 PM
Aren't there a few where one star is literally eating another?

Well, Cygnus X-1 is a binary system where the main star is being slowly eaten away by a nearby black hole, most likely the star's former companion.

stu
2004-Apr-30, 04:34 PM
Here's one that has an orbital period of 5 minutes: http://physicsweb.org/article/news/6/3/16/1

Normandy6644
2004-Apr-30, 04:42 PM
Here's one that has an orbital period of 5 minutes: http://physicsweb.org/article/news/6/3/16/1

In reply to your signature, "Astro Stu shouldn't advertize." :wink:

Padawan
2004-Apr-30, 05:38 PM
Could these white dwarves merge and become a supernova?

Normandy6644
2004-Apr-30, 06:22 PM
Could these white dwarves merge and become a supernova?

A supernova is an explosion produced when a star dies, more specifically a very massive star. White dwarves actually come about as the alternative to supernovae. A star with a lower mass will eventually shed it outer layers, leaving only a white dwarf behind. So to answer your question, no. Two white dwarves could never merge to "become a supernova."

Kaptain K
2004-Apr-30, 07:12 PM
Never say never. If the pair are radiating gravitational energy fast enough, they will spiral closer together. If they merge, and if their combined mass exceeds 1.4 solar masses, they will explode in a supernova.

Padawan
2004-Apr-30, 07:43 PM
Never say never. If the pair are radiating gravitational energy fast enough, they will spiral closer together. If they merge, and if their combined mass exceeds 1.4 solar masses, they will explode in a supernova.


Do you think it's likely that they will merge? i mean they are quite close to each other, 80 000 km according to the article above

eburacum45
2004-May-01, 09:42 AM
This extreme helium rich star seems to be the reult of a merger between two white dwarfs
http://www.arm.ac.uk/~csj/research/v652_merger.html

a movie simulation
http://www.arm.ac.uk/~csj/movies/merger.html

I expect the collision was a pretty big explosion...


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closer to home many stars are close orbiting binary pairs, such as Delta Trianguli
http://www.stellar-database.com/Scripts/search_star.exe?ID=16900

which could conceivably have inhabitable planets which orbit both stars' barycentre as if they were singular; from such a planet the suns would generally be too bright to look at, so you would only notice that they were binary if you looked at sunrise or sunset,
and if they were not eclipsing each other- which would be a frequent state of affairs.