largest star

i'm wondering what is the largest star in this universe based on its diameter?
Anyone knows?

I don't think anyone know's. The universe as a whole is still mostly unexplored by telescopes.

yeah, many are still unexplored.
the largest star that i know is IRS 5, its diameter is 3x(distance between sun-pluto) which is more than 15 billion km. Its a cold star. It's very difficult to find info about it.

I am not sure of the largest star by diameter is in the univerese. It is very hard for astronomers to guage the size of stars outside our Galaxy as our instraments aren't sensitive enough; but this one must come close.

The largest known star, in terms of mass and brightness, is the dramatically dubbed Pistol Star. The Pistol Star is closer to the center of the Milky Way than we are, and isn't visible to the naked eye on account of galactic dust. It's about 100 times the size of our sun, and burns 10,000,000 times as bright.

It's called the Pistol Star because it's believed to be the source of a giant nebula, or cloud of dust and gas. Recent pictures from the Hubble Space Telescope confirm this relationship. Originally, the Pistol may have had 200 to 250 times more mass than our sun, before it "fired off" the majority of its mass into the galaxy.

The brightest visible star in the night sky is Sirius in Canis Major, a constellation that represents one of Orion's hunting dogs. Ancient astronomers predicted warmer weather when Sirius appeared on the night sky, hence the "dog days" of summer.

starchild.gsfc.nasa.gov...

do u know its diameter?
it would be easier for me to imagine how big is that.
large=big
massive star can be small like neutron star

I don't think it is possible for scientists to give any type of accurate diameter of a star as the distances are too great. With the next generation of tools it maybe possible to measure diameters and to find earth size planets.
Anyone who states that this star is the biggest is probably just taking a guess. And anyone wjo states a star is this wide is definately taking a guess (unless of course it is the sun).

ic
tq for the info

I think the largest star so far that the astronomers have discovered is called the PISTOL STAR ,i don't know if someone of you have read or heard anything about this .But this is the largest so far ,it is estimated in size to be approximately as our milky way galaxy but with some percentage of error....The diameter of our galaxy is ..i think 100Kpc,where Kpc is the kiloparsec.There are more apparently objects that we don't know but lets talk about those ones we do.Anyone else knows about strange objects in the universe????

I think you can solve for the diameter of a star taking into account several assumptions.(My astronomy book is at home)

Mad scientist i know that the biggest star ever recorded is the pistol star but i have never read anything about it ,so if i am wrong can you please correct me ....I thought that it has a galactic diameter ,i know from astronomy that the diameter of our galaxy is 100kiloparsec...Can you please tell me where i can find some information...

I don't know if a star could be the size of a galaxy. Surely it's mass would crush it into a blackhole or something else.
As for the pistol star, it's the biggest in terms of mass discovered so far. See the above post and link.

[Edited on 21-12-2002 by mad scientist]

There's a recent discovery of the most massive if not the largest star. The latest in a series of discoveries. The new "big kid" is called WR123. For those with an interest some links:

A Spaceref article from June 10 2007 here. It's aptly titled "Astronomers Identify The Most Massive Star - Ever".

And a couple of supporting links at University of Montreal here and here.

Cheers,

Vic

[edit on 11-6-2007 by V Kaminski]

I don't know if this is the largest known star, but this video shows how small the Earth (and our sun) is relative to other stars, ending with the extreme large star "W Cephei" (by the way...we are really small!)

Oh wow,
that video really puts things in perspective... I had to laugh while I was watching it... if not for nervous disbelief in how dramatically small we really are!

Make no mistake about it, we are mere specs of dust compared to much of the rest of the universe we have discovered so far.

By the way, I don't remember Rigel being blue... then again, I probably learned of it in black and white pages, so clearly I wouldn't have known.
Why is Rigel displayed as blue?

[EDIT] I was just looking up spectroscopy results of Rigel, and I couldn't find any... I'm still wondering what it is composed of that gives it it's blueish hue. [/EDIT]

[edit on 11-6-2007 by johnsky]

Wow, that video rocks! (added it to favourites in my youtube account :p) I saw a couple images posted by another member somewhere in the space exploration forum, that were very similar, only they stopped with Antares, I believe, while that video had two even more massive stars.

As to figuring out the diameter of a star, as long as you know roughly how far away it is, and can see it, and thus know how bright it is, it should be possible to figure out how big the star is. Unfortunately, knowing how far away it is isn't always possible, and it can sometimes be very hard to tell the difference between a small, dim star that is very close and an uber-massive star that is very far away.

Always keep in mind also that most scientific measurements are usually good to perhaps a few percent, depending on the type of measurement. I wouldn't be surprised if the margin of error for a star diameter was 5 or even 10 percent. Still, I trust that most star diameters that you can find in an astronomical text are close enough to the actual thing that they can be considered reliable.

Originally posted by johnsky
I was just looking up spectroscopy results of Rigel, and I couldn't find any... I'm still wondering what it is composed of that gives it it's blueish hue.
[edit on 11-6-2007 by johnsky]

Isn't the color of a star due to the direction it's moving in and not it's composition? for example if it has a blue shift it's moving torwards us.

[edit on 12-6-2007 by DarkSide]