Which is the biggest star in the galaxy?

[Redfish]

If found that Antares and Betelgeuse are very big: around 200 solar masses. Does anyone know whether these two stars are the biggest of the galaxy?

[Raul.]

From sci.astro FAQ ( http://sciastro.astronomy.net/ ):

Subject: G.03 What are the biggest and smallest stars?
Author: Ken Croswell <galaxy@ccnet.com>,
John E. Gizis <jeg@pistol.caltech.edu>

[Table reflects most recent distances from Hipparcos.]
The most luminous star within 10 light-years is Sirius.
The most luminous star within 20 light-years is Sirius.
The most luminous star within 30 light-years is Vega.
The most luminous star within 40 light-years is Arcturus.
The most luminous star within 50 light-years is Arcturus.
The most luminous star within 60 light-years is Arcturus.
The most luminous star within 70 light-years is Aldebaran.
The most luminous star within 80 light-years is still Aldebaran.
The most luminous star within 100 light-years is still...Aldebaran.
The most luminous star within 1000 light-years is Rigel.
(Honorable mentions: Canopus, Hadar, gamma Velae, Antares, and
Betelgeuse.)
The most luminous star within 2000 light-years is Rigel.
The most luminous star in the whole Galaxy is *drum roll, please*
.... Cygnus OB2 number 12, with an absolute magnitude around -10.
(also known as VI Cygni No 12).

A table listing the nearest stars (within 12 light years) may be found
at http://www.ccnet.com/~galaxy/tab181.html. The faintest star
within that distance is Giclas 51-15 with absolute visual magnitude
16.99 and spectral type M6.5.

Wielen et al. published the following as the local luminosity function
(total number of stars within 20 parsecs = 65 lightyears). At the faint
end (abs. magnitude >12) this table is bit out of date and the numbers
are probably too high. Everything from abs. magnitude 9 to 18 is
considered an M dwarf (shows TiO and other molecules) or a white dwarf.

abs. mag Number
-1 1
0 4
1 14
2 24
3 43
4 78
5 108 Sun is here!
6 121
7 102
8 132
9 159
10 245
11 341
12 512
13 597
14 427
15 427
16 299
17 299
18 >16

[Rassilon]

What about stars at Galactic Center?...well the ones that can be seen around the black stellar matter...Since they say most there are the oldest in the galaxy...there might also be the biggest...not to mention the mysterious core...that is if it IS a star...

When astronomers look into other galaxies they see this massive cluster of stars near and around its center...with this jet of gas extruding from either end...Most say now that these may be singularities or black holes?...Supermassive condensed stellar matter ~the size of our sun?

Definately would be considered the largest object in our galaxy if it were still a star

But as far as size isnt Mira considered one of the largest?

[abiogenesis]

In Celestia, if you turn of galaxy rendering and "Follow" Sol, then zoom out until you see empty space around the cluster of mapped stars, the ones on the outside of the cluster tend to be pretty big. It makes sense since they're the farthest away that we can see. They'd have to be pretty big or pretty bright or both. HD 11247, for instance, is 439.27 RSun!

- a b i o g e n e s i s -

[ogg]

Here's the info on the brightest/biggest known star:

http://oposite.stsci.edu/pubinfo/PR/97/33.html

It's called 'the Pistol star' after the nebula the surrounds it. It featured on Astronomy Picture of the Day and another URL:

http://antwrp.gsfc.nasa.gov/apod/ap971008.html
http://starchild.gsfc.nasa.gov/docs/Sta ... ion21.html

... although both say here that it's 100 solar masses, whereas another source:

http://www.astro.ucla.edu/~tanner/gcdyn.html

...quotes it as being 200-250 solar masses.
There is a theoretical upper limit for a star's size because the internal heat/pressure in the core beyond a certain solar mass generates so much thermonuclear power that the star literally overinflates itself with it's own heated gasses and 'puffs off' the outer layers. These big ones usually have such 'puff nebulas' around tham and are called 'Wolf-Rayet stars' - more then ~40 solar masses.
On the other hand, supermassive stars - 'megasuns' - might have produced 'hypernovas' in the early life of the universe: this is one theory put forward to account for the current GRB (gamma-ray burster) mystery. Megasuns would have ~270 solar masses.
Here's a graphic that I clipped from an article some time ago:

http://homepages.ihug.co.nz/~brusse/225511F2.JPG

disturbing, eh?

[Astrojockel]

A good candidate in celestia for big size i found is HD 184283, a M9V star with 871,92 solar radii, but there?s a discrepancy in starclass because the V stand for a mainstream star (Ia for hypergiant should be better). In real life the companion of VV Ceti could be the best candidate for the biggest (not heaviest) star. Some described it with 1,6 billion km radius.

Some other "kings" in the classes size, mass and luminosity can found here:

http://www.astro.uiuc.edu/~kaler/sow/sowlist.html

look for Rho Cas and P Cygni

[D.Edwards]

If you check most of the literature and online refrences you will find that a galaxy with jets comming out its north and south pole are, or were called Quasars. The jets are because the super massive black holes are feeding on mater in the galaxies center. A galaxy without the jets doesn't mean it doesn't have a super massive black hole just that the black hole isn't feeding or sucking in any mater. Its spleeping so to speak. Like a dormant volcano. When enough mater is drawn in again the jets reform. Like a volcano erupting. Its believed that our galaxies super massive black hole is in such a slumbering state at this time. All thats needed is enough mater to strean into the black hole for it to awaken and start making jets again.
Then lets not forget that the MilkyWay galaxy is on a colision corse with the Andromeda galaxy. I think they merge in like 100 million years or so. Maybe are decendants will be around to see that event if our species is lucky enough not to snuff itself out or be snuffed out by someone else.

[Raul.]

What about stars at Galactic Center?...well the ones that can be seen around the black stellar matter...Since they say most there are the oldest in the galaxy...there might also be the biggest...not to mention the mysterious core...that is if it IS a star...

One thing is for sure, if a star is very old then it's rather small. Big stars last only a few million years before going off as supernovas (well, most of them).

[Thilo]

What about stars at Galactic Center?...well the ones that can be seen around the black stellar matter...Since they say most there are the oldest in the galaxy...there might also be the biggest...not to mention the mysterious core...that is if it IS a star...
t Mira considered one of the largest?

At stars, biggest != oldest. Stars that are very big generally have a short life time. The smaller the sun, the longer it lives.

EDIT: oops, missed out Raul's comment, sorry ;)

[Rassilon]

Well as much as our feeble minds can comprehend about our universe...is well all we know right now...We pretty much base our entire science around the premise that it is the same everywhere else in the universe...This may seen fine and dandy to us...we must remember not to be so arrogent when our neighbours come to visit in some distant future ...So who's to say really that our galactic center is a star or even a black hole...We just therise that it is so...Hopefully one day we will know and see with our own eyes the mystery

It seems to me the central object should be much more massive than 100 - 250 solar masses considering there are stars twice that size in freespace...Mira I mentioned before is ~500 solar masses...and if the center is a black hole...they are supposed to be super-massive...

And isnt a black hole generally 100 million times more luminious than our own sun because of the event horizion? This is from an older astronomy book so this now could be considered an old theroy....

[Thilo]

It is only more luminous when it is sucking matter.

[ogg]

Here's an astronomer answering a question very similar to the one that started this thread:

http://imagine.gsfc.nasa.gov/docs/ask_a ... 0616b.html

Note that this guy places Mira as bigger in size then Betelgeuse, but not more massive then his own 'biggest known star' candidate Eta Carina, which I'd forgotten about. Bear in mind that the problem with answering questions like this is that any given star's mass can only be estimated by using a theoretical model, it's angular size (from tricky interferometry readings) and its absolute magnitude... which in turn can only be calculated from the apparent magnitude and distance/paralax measurement. The problem is that most of these big big stars we're talking about are too far away to have a nice, accurate paralax measurement or be resolved with interferometry. Even the Hipparcos catalog starts getting big error estimates built into it for the most distant ones so it's mostly guesswork at the moment to say what's actually the brightest star, and theorising based on guesswork to say what's the most massive.
So different scientists will say different things in answer to this question, depending on how hand-wavy they want to get in terms of second-guessing the data.

Besides, you can see from Celestia that only stars in a tiny corner of the galaxy have actually been measured for distance (and most of the galaxy isn't even visible to us), so it's a pretty good bet that the biggest star in the galaxy is one we don't know about yet.

- Of course, if you count black holes or other colapsars as stars (I wouldn't, because they don't radiate autonomously due to internal thermonucler reactions... just a matter of definition I guess), then the biggest one in our galaxy would indeed have to be the 'central' black hole (or whatever it is) at SagA*.

http://physicsweb.org/article/news/4/9/15
http://www.cnn.com/2001/TECH/space/09/0 ... lack.hole/

[Joris]

I've always thought that Mu cephei or the Garnet stay was the largest.. The data in Celestia doesn't suggest it but other sources say it's 2536 solar radii.. and would almost fill the orbit of saturn. Class M2 Ia Red Giant. Definitely not the biggest by mass though.

Anyway.. as other's explained this is a sketchy subject.. it's a lot of guesswork.

[Rassilon]

Possibly 2.6 million times more massive I cant even imagine that...If the mass was relative in size that would be 2.6 trillion kilometers in diameter! Half a light year If Sag A was a star at one point that might have been its diameter...or close....