Hubble Chronicles Mysterious Outburst

An eruptive star that brightened to 600,000 times its initial intensity and briefly outshone all others in the Milky Way Galaxy has astronomers amazed and puzzled over what happened...The star, named V838 Monocerotis, has suddenly grown so big that if placed in the center of our solar system it would engulf Jupiter.

Comments

War

[tsa]

That's an alien war where one race destroyed the others' solar system.

Re:War

[flonker]

My first thought was also that it was some kind of consequence of war. Although I thought of the fact that Manhattan Project era scientists were unsure whether a detoned nuke would stop, or continue in a chain reaction that would engulf the world, turning it into a second, smaller sun.

Re:War

[tsa]

It was meant as a joke. But maybe you can make a weapon with which you can expode a sun. Shouldn't be too hard considering the sun is one giant atomic bomb anyway...

Re:War

[beat.bolli]

considering the sun is one giant atomic bomb anyway...

Wrong. The sun is a fusion rector, not a fission reactor.

Re:War

[tsa]

So it's sort of a H-bomb. Still an atomic bomb in my book. But maybe I'm wrong.

Re:War

[neur0maniak]

Yeah, you could just connect a stargate to one that's already being sucked into a black hole, and then aim it for a star with one of the goa'uld motherships you have lying around all over the place...

(btw. Sun is the name of ONE star. Use either "The sun" or "A star", instead of "A sun")

Re:War

[Christopher Thomas]

It was meant as a joke. But maybe you can make a weapon with which you can expode a sun. Shouldn't be too hard considering the sun is one giant atomic bomb anyway...

If it's easy, it should happen all over the place already through natural processes. This does not seem to be the case (novae and supernovae are quite rare in the grand scheme of things).

Stars are very good at being self-balancing systems. As reaction rate increases, so does photon pressure, which makes the star less dense, which reduces reaction rate. This breaks down only in special cases.

Unstable giant stars, like this star appears to be, are one of those cases. Our sun may end up doing something not very different from this in a few billion years as its core runs out of fuel.

Violent explosions only occur when something overrides fusion-produced photon pressure and the star starts collapsing. This mainly happens when a star runs out of fuel, and stops again when either a new fusion stage starts, or when degeneracy pressure takes over.

Re:War

[Anonymous Coward]

hydrogen bombs are atomic bombs too:)

Re:War

[Usquebaugh]

Gravity sucks almost as much as your idea.

Re:War

[hplasm]

fusion rector

n. Clergyman who aims to unite the church.

Re:War

[scorp1us]

This is true for *EVERYTHING* today. If it exists today, then it's stable. I can think of no process that has not completed a single cycle. If my assertion is correct, then there are no unstable systems.

The only possible exception that comes to mind is the expansion of the universe, but current data indicates that we will forever expand, and never collapse. That is the only acyslic thing in the universe. (Known to me)

I call stabilities "reinforcing harmonics". It's a pattern of behavior that doesn't lead to it's own destruction. (Not that it won't ever be destroyed, but it won't destroy itself) Life is one such example (you don't exist and die out, you exist and propigate - any life that is life has since stablized), self-regulating stars are another. But stars are only self-regulating for a while - while they have fuel enough to hold a stable reaction - then they begin to die.

This implies existance a 2nd order stability, stability of stabilities. The longer you last, the higher your 2nd order stability. This follows the first rule - if you're existing today, then you've got a decent 2nd order stability.

So to recap, if it wasn't stable, it'd be gone by now. The only way for that to be incorrect is for a massive amount of stored energy (or lack of) that would disrupt the reinforcing harmonics

Supernova?

[Anonymous Coward]

Isn't this typical behaviour of a star going supernova?

Re:Supernova?

[alnapp]

from the article:
"Oddly, it isn't hot and eruptive in the manner of a supernova or nova, both of which toss off outer layers in explosive fits. Instead, V838 Mon, as astronomers call it, achieved remarkable brilliance while swelling to gargantuan size and remaining cool at its surface."

wierd shit

Re:Supernova?

[Anonymous Coward]

That may very well be the first time a sun has been described as "cool at its surface".

Re:Supernova?

[Simon Field]

Suppose the star is moving towards the earth.

As it periodically swells and casts off a dust nebula, it could move to our side of the past nebulae (assuming that the less dense nebula moves slower than the star).

Now the nebula acts as a reflector, and there is less dust between the star and earth to hide it.

It could be that these effects magnify the apparent brightness, compared to otherwise similar stars that stay within their obscuring nebulae.

They probably have enough data to rule this out, and the orbiting companion theory is more likely, but it would be interesting to know if you could explain some of the 600,000 fold brightness this way.

Re:Supernova?

[barakn]

That's one of the wackiest theories I've ever heard.

1. If the star is moving at a certain velocity, then the average velocity of a particle in a cast-off shell of dust will be at the star's velocity. In other words, the star will stay centered in any spherical shell of material it gives off (yes, I know, some neutron stars get kicked out of their nebulae, but that's a far more energetic process). An interstellar wind, if present, would destroy the spherical shape of the nebula.

2. The nebula is acting as a reflector, no doubt, but it is so thin that the star is perfectly visible through it anyway. It's the red star in the photo(s).

3. The only way this could "magnify the apparent brightness" of the star is if the star and nebula were not resolvable as separate objects. Then light reflected from the nebula could be mistaken as light from the star (ignoring spectral techniques). But the photo is of a fully resolved nebula and star. A child could distinguish light from the star vs. reflected light from the nebula.

Re:Supernova?

[barakn]

4. The illuminated portions of the nebula actually lie in front of the star. There hasn't been enough time to see reflections from the backs or sides of the shells. The ones we've seen are, after all, 4-7 lightyears in diameter.

5. Their distance estimate of 6 kpc was a lower limit. If anything it was even further away and brighter.

maybe ...

[Anonymous Coward]

... it had tourette's?

Puberty

[wanderb]

Maybe it's going through puberty? Explosive growth without getting any brighter =;-]

Re:Puberty

[Sabbath.sCm]

I thought it got brighter than the other stars in the Milky Way?

better picture

[An Onimous Cow Herd]

Courtesy of Astronomy Picture of the day

"Suddenly" actually does mean suddenly here

[ksdd]

The star, named V838 Monocerotis, has suddenly grown so big...

While I was RTFA, I pretty much expected that this "sudden" event would be revealed as sudden only when measured in geologic or cosmic time; say, a few thousand millenia or so. The fact that this happened over only a few months is fascinating.

Starlifting?

[seanellis]

http://www.homoexcelsior.com/omega.db/datum/refere nce/star_lifting/177

New physics involved?

[Muhammar]

This event goes contrary to everything what is known about the star life cycle so far. The most strange thing is the luminosity and the fact that resulting object is a big star, and not a collapsed object (like black hole, neutron star or white dwarf)

Re:New physics involved?

[Doctor Fishboy]

This event goes contrary to everything what is known about the star life cycle so far.

New physics just for this star? I doubt it.

One reasonable suggestion without reaching for mysterious new physics is that it is part of a binary system, with a compact object (neutron star, white dwarf or possibly black hole) in a highly eccentric orbit around this main sequence star.

Every x number of years, the compact object skids in on its highly eccentric orbit, and slams through the upper layers of the visible star. Material falls onto compact object, flares up and heats the outer layer of the main sequence star, compact object whizzes out again and is not seen again for another few hundred years or so. The fraction of total mass ejected from the main star is miniscule, so this process does not significantly alter the main star's evolution on the timescale of a few million years, hence the repeated shells of dust seen in these light echoes.

Binary systems of this types have been known about for quite a while (well, on the order of 20 years). The trick is looking for the signature of the compact object, which is a difficult detection.

Dr Fish

Re:New physics involved?

[Christopher Thomas]

This event goes contrary to everything what is known about the star life cycle so far.

Not really. As far as I understand, it's actually pretty typical of the unstable time when a star either enters or leaves the red giant phase. We're seeing a "planetary nebula" being born.

Re:New physics involved?

[barakn]

Oh yeah? Then explain these quotes:

"To create an outburst as sudden and as luminous as V838 Mon's, you have to do something pretty significant to the star," Kwitter said. "Right now we have no idea what. There are some interesting theories involving binary companion interactions or planet swallowing that may turn out to be relevant, but the truth is that nobody knows yet why this happened."

"This object got bigger and brighter and cooler, but we don't know why," Starrfield said today. "Right now we know the effects and we're trying to use the effects to determine the cause."

Re:New physics involved?

[ktulu1115]

Couldn't this be caused due to a helium flash? I know for a short period stars which have masses high enough to burn helium undergo a very short and energetic outburst.

Old News...

[Big Sean O]

According to the article, this happened 20,000 years ago...

*yawn*

Also on APOD

[Anonymous Coward]

Light Echoes from V838 Mon.

shorter timescales than that

[Doctor Fishboy]

The collapse of the core of a star as it is about to go supernova takes less than an hour or so, and it is in the shock wave of the exploding star that the really heavy elements are formed from nucleosynthesis. Not everything in astronomy works on gigayear timescales!

Dr Fish

Todo:

[slittle]

42. Stay the fuck away from "V838 Monocerotis" today.

Check.

Well, that's me done for today. Time to troll Slashdot...

Re:Todo:

[biglig2]

You mean "Stay away from V838 Monocerotis 20,000 years ago".

Re:Todo:

[bozojoe]

I better make sure my infinite improbability drive checks the mapquest option to avoid that toll-road

Larger still image

[stienman]

For those who want a screen filling larger image, 1651x1651, it is the subject of today's Astronomy Picture of the Day (APOD).

-Adam

Re:Larger still image

[msheppard]

For those who failed to click this link on the day it was posted (it changes every day, yes EVERY DAY, not just weekdays, not just when the guy isn't on vacataion, EVERY DAY for like 7 years people.)

The image in question can be found at this, non-changing link:
APOD for 030327.

MMMMmmmm.... APOD.

M@

Totally Dude

[Mr.Phil]

"In fact, at present it is one of the coolest stars known," Bond told SPACE.com.

Well, it sure looks pretty damn cool.

May not be that big

[Gnissem]

To determine the size of a star, you need to know two things...temperature and total energy radiated(luminosity). (Stefan-Boltzmann law). Temperature is relatively easy to get for stars from their color (spectrum). Luminosity is harder. We need brightness and distance to determine how much energy a star is putting out. Brightness we can easily measure but distance for anything but the closest stars is very difficult to determine. They based their conclusion on a guess that this star is 20,000 light years away. While this is definitely an interesting event, if that guess is wrong it might not be nearly as dramatic as they say.

Re:May not be that big

[Christopher Thomas]

Brightness we can easily measure but distance for anything but the closest stars is very difficult to determine. They based their conclusion on a guess that this star is 20,000 light years away. While this is definitely an interesting event, if that guess is wrong it might not be nearly as dramatic as they say.

According to the article, they determined the distance by looking at the companion star in the pair, which is of a well-known type, with a well-known temperature/luminosity relation. That gave them a reasonable distance estimate for the companion, and so for the giant.

Too cool for science

[!splut]

"In fact, at present it is one of the coolest stars known," Bond told SPACE.com.

The astronomer then proceded to slick back his hair and donned a pair of shades, while rythmically snapping the fingers of his free hand.

"Oh, yeah," added Bond.

Well, we can expect the Monks soon :)

[Arthur Dent]

For those who don't know what I'm talking about, read The Fourth Profession.

A series of photos

[barakn]

Hubble took a series of 4 photos, and you all have been looking only at the last of them. Also is a link in case you want large versions of each individual photo, and another for links for all the text, images, and video concerning the event. I'm surprised Doctor Fishboy never pointed this out.

it's not like a supernova. . .

[astrobabe]

I was with Mark (Wagner) and Sumner (Starrfield) when we got the spectra. . .now I'm going to be really pissed if I'm not on the paper since I was the one taking the spectra. . . But anyhow. . .the spectra is really interesting, there are P Cygni profiles for every emission line in the spectra (P Cygni's look like half a gaussian in emission with a sharp cutoff to be half a gaussian in absorption). This object was actually noticed by people looking at variable stars and then was picked up by some other folks in Arizona which showed the light echos even in the relatively low resolution images we got on the ground compared to our HST ACS images.

Re:it's not like a supernova. . .

[barakn]

From the paper in Nature, a list of the authors: H.E.Bond, A.Henden, Z.G.Levay, N.Panagia, W.B.Sparks, S.Starrfield, R.M.Wagner, R.L.M.Corradi & U.Munari

So either you're on the paper or you're not, depending on who you are.

Explained:

[X86Daddy]

Their version of SETI @ Home involves manipulating a nearby star in a highly noticable manner. Now that they have our attention, they await our transmitted replies. :-)

(yeah yeah, light travels too slowly, etc...)

Any _CLEAN_ Images of this event?

[JUSTONEMORELATTE]

While I love the Astronomy Picture Of The Day and the similarly-cool Hubblesite pics of this event, All the good-sized images have that annoying twinkly-crosshairs look to them. The Hubblesite pics include this small image without them, but all of the large-format images that I can find have the "star filter" applied. Does anyone know where I could find a large, unaltered image or images?
--

Re:Any _CLEAN_ Images of this event?

[barakn]

Surprise! The "star filter" effect is in the clean, unaltered image. Your small image is just too small to show them. The crosshair produced by each star is a result of diffraction of light in the telescope. Diffraction is the inevitable result of any optical system that isn't infinite in size and is often what limits the resolution of modern telescopes (in the old days it was our messy atmosphere). Diffraction from the aperture of a telescope results in pointlike light sources being resolved as a series of circles surrounding a central dot (Airy disk). The spikes come from the supports that hold the secondary mirror. They are in front of the primary mirror and therefore in the path of incoming light. You might argue that not all stars in Hubble photographs have them. This is because the stars had to be overexposed to capture the much fainter nebula.

Re:Any _CLEAN_ Images of this event?

[barawn]

Actually, not quite. The spikes come from overexposure of the CCD pixels - CCDs tend to bleed in two perpendicular directions when the amount of light exceeds their dynamic range (they "bubble over").

You are correct that the "star filter" effect is the unaltered image. Bright stars "bloom" in CCD images. This's typically why you want to try to avoid bright stars in a deep-field image: the bright stars will just overwhelm the whole image. This'd happen on film, too, but CCD produces the weird "crosshair" effect.

Re:Any _CLEAN_ Images of this event?

[barakn]

Since when have CCDs bled "in two perpendicular directions"? If I posted enough links of CCDs bleeding in only one dimension, would you eat a crow? From one of my favorite satellites, Yohkoh. From a random web page. A great shot of the infamous UFOs from SOHO. And finally, from the Hubble website itself, a great example of CCD bleed and diffraction spikes in the same photo! The CCD bleed is the bar, and the diffraction spikes are the crosshairs. Check your facts before you post.

Re:my 1st comment

[barakn]

A proper discussion would have involved momentum. I implicitly assumed the dust particles all had the same mass. It doesn't change the essence of the argument, however.

a more technical article

[barakn]

Here's a link to Bond's paper in Nature.

Lets hope we get to see a supernova

[Hoch]

A super nova would be the coolest thing ever as it would light up a large area of the sky for about a year. But then again, a supernova might not be to friendly for all the aliens. Damn aliens, making all our fun into a giant guilt trip. Hoch