Light Echoes from V838 Mon, diameter? (APOD 03 Feb 2008)

[harry]

Hello All

Light Echoes from V838 Mon
http://antwrp.gsfc.nasa.gov/apod/ap080203.html

The image is fantastic

What is surpricing in this:

What caused this outburst of V838 Mon? For reasons unknown, star V838 Mon's outer surface suddenly greatly expanded with the result that it became the brightest star in the entire Milky Way Galaxy in January 2002. Then, just as suddenly, it faded

More info
V838 Monocerotis
http://en.wikipedia.org/wiki/V838_Mon

Could this be similar
NGC 6369: The Little Ghost Nebula
http://antwrp.gsfc.nasa.gov/apod/ap021108.html


Maybe this is an option

http://csep10.phys.utk.edu/astr162/lect ... novae.html

degenerate conditions.
javascriptlaunch('../binaries/accreting/degenerate.html')

Thermonuclear ignition under degenerate conditions is thought to be a key component in nova explosions, X-ray bursters, type 1a supernovae, and in what is called the helium flash in red giant stars.

Another option maybe be explained by the properties of plasma.
Z-pinch dynamics

[lewishb]

looks all the world like what we on Cape Cod called a "queen fish"

the mouth was as wide as the body which was shaped like two pie plates together...... In the picture you can even see the eye on the (our) right side... really spooky ...... The fish I saw on the beach when i was a youngster was about 5 feet in diameter. The fish was hollow inside I guess it swollowed its prey and the huge cavity inside became its stomach......

Lewis

[JohnD]

Four years ago, the Hubble site published an 'animated' display of these light echoes as they had developed in time. The images are still up, at http://hubblesite.org/gallery/album/ent ... r2004010b/ but I can't find the 'video'. Can anyone supplement them with this new view, and any others between 2004 and now and remake the animation? The original was fascinating.

John

[rex27]

Does anyone else note the striking resemblance to the firefox icon?

[orin stepanek]

Four years ago, the Hubble site published an 'animated' display of these light echoes as they had developed in time. The images are still up, at http://hubblesite.org/gallery/album/ent ... r2004010b/ but I can't find the 'video'. Can anyone supplement them with this new view, and any others between 2004 and now and remake the animation? The original was fascinating.

John

Hi John! I found one on Youtube. Hope you like.

http://www.youtube.com/watch?v=dbFccJegXP8

Orin

[rockwiler]

Shouldn't the diameter be twelve light years? The light will have traveled six light years in each direction from the star since six years ago. Unless the picture is three years old - it doesn't say - but it usually says the picture is old when that's the case.

Cool picture. Looks like fur!

[neufer]

Shouldn't the diameter be twelve light years? The light will have traveled six light years in each direction from the star since six years ago. Unless the picture is three years old - it doesn't say - but it usually says the picture is old when that's the case.

Actually diameter isn't even the "proper" word to use in the first place.

The 2002 light burst echo is presenting successively larger parabolic cross sections whose "semi-latus rectum" (if you'll pardon the French ) is now at ~6 light years.

Tomographic techniques should allow for a more or less complete 3D picture of the entire cloud.

[JohnD]

Thanks, Orin!

Great animation, shame about the presentation.
(why do scientists think that they need to patronise their audience?)

John

[Case]

Without any 'funny' presenters...
http://www.youtube.com/watch?v=v0DUvu6S6B4
http://www.youtube.com/watch?v=j2NvAPSwUc0
http://www.youtube.com/watch?v=Yw-CJzBatWU

[rockwiler]

Oh yeah, that would make sense. Thanks.

[NoelC]

I wonder if this object is visible/photographable by amateur equipment. As far as I know no one has attempted it. Perhaps it is just too dim and too small for ground-based photography.

By the way, I don't think the APOD image is the latest one of this object. Check here: http://www.spacetelescope.org/news/html/heic0617.html

-Noel

[DavidLeodis]

Shouldn't the diameter be twelve light years? The light will have traveled six light years in each direction from the star since six years ago. Unless the picture is three years old - it doesn't say - but it usually says the picture is old when that's the case.

Cool picture. Looks like fur!

The image was taken on February 8, 2004 according to information that is brought up when clicking on the 'above image' in the explanation to the APOD when online. Yes it is a great picture. Not sure that it looks like fur though!

[neufer]

By the way, I don't think the APOD image is the latest one of this object. Check here: http://www.spacetelescope.org/news/html/heic0617.html

-Noel

Thanks for this, Noel. The 12,270 KB QT hires movie is fantastic!!!
The movie runs from Feb. 2002 to the Sept. 2006 view shown at
http://antwrp.gsfc.nasa.gov/apod/ap061103.html

It is clear from the movie that the cloud "echo" itself stops expanding in early 2005 so the "diameter of the cloud itself" is indeed about 6 light years. The cloud appears to be roughly spherical and centered on V838 Mon so it probably IS, in fact, accumulations of ejecta from that very active star from over the last few thousand years.

The current APOD "echo" image from Feb. 2004 shows a parabolic slice of this "spherical" cloud with a semi-latus rectum of 2 light years which lights up both the cloud 1 light year directly behind V838 Mon and the edge of the cloud about 1 light year in front V838 Mon (though almost 3 light years out to the side):

Draw a circle containing the fuzzy cloud itself: X*X+Y*Y = 10
& a parabola for the illuminated echo slice: Y= (X*X)/(2*2) - 1

The Sept. 2006 view shown at
http://antwrp.gsfc.nasa.gov/apod/ap061103.html
is a reasonable approximation of a "flat" cross section of the cloud one and a half light years behind V838 Mon:

Draw a circle containing the fuzzy cloud itself: X*X+Y*Y = 10
& a parabola for the illuminated echo slice: Y= 2.3[(X*X)/(4.6*4.6) - 1]

After 6 years now there should be little of the cloud left to see:

Draw a circle containing the fuzzy cloud itself: X*X+Y*Y = 10
& a parabola for the illuminated echo slice: Y= 3[(X*X)/(6*6) - 1]

Note: The "furry" structure may emulate actual magnetic field lines.

[Keldor314]

Actually, the echo is in the form of an elipsoid, with V838 Mon at one focus and us (the observer) at the other. This makes sense when you think of the photons (all 14 of them) that traveled past earth before hitting soomething 3 lightyears behind us and bouncing back.

Thus, the light echo technically covers the entire sky. Why do we only see only the fuzzy blob around V838 Mon then? Simple - this is a very skinny, long elipse, and once you look beyond the section behind V838 Mon, the section of the elipsoid you're looking at moves away from V838 Mon fast. Thus, the intensity drops down toward zero rather precipitously. As the echo expands, though, the intensity falloff will become slower, as the elipsoid becomes rounder, eventually becoming nearly spherical over the next few tens of thousands of years.

[neufer]

Actually, the echo is in the form of an elipsoid, with V838 Mon at one focus and us (the observer) at the other. This makes sense when you think of the photons (all 14 of them) that traveled past earth before hitting something 3 lightyears behind us and bouncing back.

Yes but of ALL the approximations I've made thus far approximating your ellipsoid with my paraboloid is the least objectionable. (Some of those flareup photons even hit Hubble's paraboloid mirror in February of 2002 and focused just fine without the need for an ellipsoid mirror.)

Thus, the light echo technically covers the entire sky. Why do we only see only the fuzzy blob around V838 Mon then? Simple - this is a very skinny, long elipse, and once you look beyond the section behind V838 Mon, the section of the elipsoid you're looking at moves away from V838 Mon fast. Thus, the intensity drops down toward zero rather precipitously. As the echo expands, though, the intensity falloff will become slower, as the elipsoid becomes rounder, eventually becoming nearly spherical over the next few tens of thousands of years.

We see only the fuzzy blob immediately around V838 Mon because the only dark material that is BOTH dense enough and close enough to be adequately illuminated by V838 Mon's flareup lies in a nearly spherical cloud of 6 light years diameter centered on V838 Mon. Once the ellipsoid/paraboloid envelope extends beyond this cloud (which it is NOW doing) there will be little left to see (supposedly).

The major axis of your ellipsoid is indeed growing at the speed of light but the minor axis has been growing much faster than that so that eventually it will indeed become "nearly spherical over the next few tens of thousands of years" but I'll be surprised if there's anything new to see in even the near future.

[harry]

Hello All

Thank you Orin for the Link

http://www.youtube.com/watch?v=dbFccJegXP8

and

Case

Without any 'funny' presenters...

http://www.youtube.com/watch?v=v0DUvu6S6B4
http://www.youtube.com/watch?v=j2NvAPSwUc0
http://www.youtube.com/watch?v=Yw-CJzBatWU


Great movie clips

[JohnD]

http://www.youtube.com/watch?v=v0DUvu6S6B4
Great movie clips

The above clip animates a white dwarf/red giant pair, where the dwarf draws off matter from its companion, as in the model for a supernova. Then the giant, not the dwarf explodes!
Have I got it wrong, is this nonsense or an 'alternative theory'?

John

[neufer]

http://www.youtube.com/watch?v=v0DUvu6S6B4
Great movie clips

The above clip animates a white dwarf/red giant pair, where the dwarf draws off matter from its companion, as in the model for a supernova. Then the giant, not the dwarf explodes! Have I got it wrong, is this nonsense or an 'alternative theory'?

A nova may occur when a white dwarf draws off so much matter from its red giant companion that *the white dwarf explodes* :
http://csep10.phys.utk.edu/astr162/lect ... novae.html

This may be what is happening with V838; however, the novelty here is that there is a surrounding gas cloud (possibly from previous such nova explosions) being lit up by the most recent explosion.

[harry]

Hello All

What triggers a nova or a supernova is really unknown.

One theory is that the core loses matter and thus mass resulting in the solar envelope expanding and uncontrollable heat release. The Fe built over billions of years is shot by high energy matter that causes the Fe to be broken down via fission chain reactions to H which in turn undergoes fusion chain reactions. Both chain reactions give off huge amounts of energy resulting in a nova or supernova.

[starnut]

Hello All

What triggers a nova or a supernova is really unknown.

One theory is that the core loses matter and thus mass resulting in the solar envelope expanding and uncontrollable heat release. The Fe built over billions of years is shot by high energy matter that causes the Fe to be broken down via fission chain reactions to H which in turn undergoes fusion chain reactions. Both chain reactions give off huge amounts of energy resulting in a nova or supernova.

Hello, Harry, long time no see. I see that you are still sprouting nonsense! The mechanisms causing a nova and a supernova are well known and well proven! Your alternative explanations make no sense at all.

[harry]

Hello Starnut

You still hold up to your name.

What I explained is one theory.

Do you think its nonsense?

Than I would ask you to read up on supernova

[JohnD]

Now, now, play nicely, children!

Harry, Starnut, suggest you post evidence for your opinions.
This is supposed to be a 'science based' Msb. There are plenty of spats and personal differences in science (tell me about it!), but the convention is that if you disagree with someone else's view, you offer evidence to back up your opinion.

This gives weight to your opinion, and informs others who have not studied the subject in as great depth as you.

As I started the 'is this how novas happen?' debate, I feel a responsibility, and a thirst for REAL knowledge, that name calling cannot satisfy. Ok, now carry on!

John

[harry]

Hello John

Keep smiling mate

No name calling.

As for evidence. No one person can give evidence for supernova. Just theories.

What gives the energy for the supernova?

What triggers it all?

One needs to look at the properties of the star and than apply science to the logic and hope that we are on the right path.

======================

Was the brightest supernova the birth of a quark star?

http://space.newscientist.com/channel/a ... gy/dn12514

Interesting reading


=======================


In the near future I will post info on supernova. Maybe make it a new topic.

[JohnD]

harry,
Are you a sockpuppet for Fiery Ice or craterchains?
They come up with exactly that sort of gnomic and knowing remarks, that provide the readerv with no information at all.

dialogue ended

[starnut]

OK. Let's start with a nova.

A nova is simply a white dwarf that draws matter off its red giant companion in a close binary system and accumulates too much of it on its surface. The white dwarf has a very strong gravitational force on its surface and also very high temperature, ranging from 100,000K to 200,000K (Our sun's surface temperature is only 6000K). The accumulated matter reaches a certain density and temperature (I am not sure how high) that causes a thermonuclear reaction to start, causing the surface to explode outward. This causes a spike in the brightness of the white dwarf. The brightness then dies down, and the cycle is repeated with more matter from the red giant. That video is not correct, made with the erroneous assumption that the bigger companion is the one that explodes simply because it is bigger.

A supernova can be of two kinds. In a Type 1a supernova, a white dwarf, again in a close binary system like above, accumulates more matter from its companion to the point where its mass exceeds 1.44 solar masses, called Chandrasekhar limit. This makes the white dwarf's interior unstable, initiating a thermonuclear burning that turns into a supernova explosion which destroys the white dwarf entirely. Since a white dwarf is just the carbon-oxygen core of a small star like the sun, no hydrogen has been detected in the supernova remnant. The other kind of supernova is Type II, a core collapse supernova. This happens only to stars having more than 8 solar masses. The nuclear fusion in a star of that size goes beyond helium fusion which leads to carbon-oxygen fusion which leads to oxygen-neon fusion which leads to silicon-sulfur fusion which leads to iron which cannot be fused without input of energy! The sudden cessation of fusion at the iron core causes loss of energy that has been exerting outward pressure against the inward gravitational force of the overlaying stellar mass. A catastrophic core collapse occurs until the core reaches neutron degeneracy, which stops further collapse. The rapidly infalling matter in the overlaying envelope then bounces off this neutron core, setting off a supernova explosion. Since the star still has its hydrogen envelope at the moment of the core collapse, hydrogen is detected in the supernova remnant. For a very massive star. the core collapse does not stop at neutron degeneracy; the shock of the infalling matter bouncing off the core will continue the collapse until a black hole is created.

That is a bit oversimplified explanation how a supernova occurs. You can find more info by googling supernova or reading standard astronomy textbooks. No way, can a star's iron core be fissioned (decayed) to hydrogen like Harry said! Harry likes to give short comments with oodles of links but no in-depth explanations of his own. His wacky ideas are, well, just wacky.

Sorry, Harry.