APOD: 3D Homunculus Nebula (2014 Jul 17)

[APOD Robot]

3D Homunculus Nebula

Explanation: If you're looking for something to print with that new 3D printer, try out a copy of the Homunculus Nebula. The dusty, bipolar cosmic cloud is around 1 light-year across but is slightly scaled down for printing to about 1/4 light-nanosecond or 80 millimeters. The full scale Homunculus surrounds Eta Carinae, famously unstable massive stars in a binary system embedded in the extensive Carina Nebula about 7,500 light-years distant. Between 1838 and 1845, Eta Carinae underwent the Great Eruption becoming the second brightest star in planet Earth's night sky and ejecting the Homunculus Nebula. The new 3D model of the still expanding Homunculus was created by exploring the nebula with the European Southern Observatory's VLT/X-Shooter. That instrument is capable of mapping the velocity of molecular hydrogen gas through the nebula's dust at a fine resolution. It reveals trenches, divots and protrusions, even in the dust obscured regions that face away from Earth. Eta Carinae itself still undergoes violent outbursts, a candidate to explode in a spectacular supernova in the next few million years.

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[geckzilla]

Do you think the will of a thousand astronomers could coerce it into exploding? Ok, definitely not, but I really wish this sucker would pop in my lifetime.

[ShaileshS]

I'm a bit confused. If it already erupted then we are still thinking it to be a candidate for becoming supernova in future ? Where would the material come from ? I think I'll have to do some more reading on this ...

[Nitpicker]

I'm a bit confused. If it already erupted then we are still thinking it to be a candidate for becoming supernova in future ? Where would the material come from ? I think I'll have to do some more reading on this ...

I, too, only just learnt that there is such a thing as a "supernova imposter" and that Eta Carinae is/was one.

See:
http://en.wikipedia.org/wiki/Supernova_impostor

[Ann]

Eta Carina underwent a fantastic brightening during the 19th century, but it did not go supernova. Instead, Eta Carina became a supernova impostor.

http://en.wikipedia.org/wiki/Supernova_impostor wrote:
Supernova impostors are stellar explosions that appear at first to be a type of supernova but do not destroy their progenitor stars. As such, they are a class of extra-powerful novae. They are also known as Type V supernovae, Eta Carinae analogs, and giant eruptions of luminous blue variables LBV.

Supernova impostors can turn into real supernovas later.

http://en.wikipedia.org/wiki/Supernova_impostor wrote:
One supernova impostor that made news after the fact was the one observed on October 20, 2004, in the galaxy UGC 4904 by Japanese amateur astronomer Koichi Itagaki. This LBV star blew itself up just two years later, on October 11, 2006, as supernova SN 2006jc.

Therefore Eta Carina could go supernova for real in the future, even though it has already been a supernova impostor.

Ann

[Nitpicker]

Do you think the will of a thousand astronomers could coerce it into exploding? Ok, definitely not, but I really wish this sucker would pop in my lifetime.

Would you travel south to see it, if it pops?

[geckzilla]

Do you think the will of a thousand astronomers could coerce it into exploding? Ok, definitely not, but I really wish this sucker would pop in my lifetime.

Would you travel south to see it, if it pops?

Are you offering a couch to crash on?

[Nitpicker]

Do you think the will of a thousand astronomers could coerce it into exploding? Ok, definitely not, but I really wish this sucker would pop in my lifetime.

Would you travel south to see it, if it pops?

Are you offering a couch to crash on?

Well, I wasn't thinking that when I asked, but if you need it, you'd be welcome. (Mind you, the HST or JWST will no doubt offer better images online, than anything my scope could make from my suburban backyard.)

[bjmb]

" Between 1838 and 1845, Eta Carinae underwent the Great Eruption" - you mean, surely, " "Between 1838 and 1845, Eta Carinae was observed to undergo the Great Eruption" - the thing itself occurred thousands of years ago.

[JohnD]

That's no "Homunculus"!

That's a snapdragon flower!

JOhn

[FloridaMike]

Having that 3D model on the coffee table would be a great conversation starter. "What do YOU think it is?" Ha!

[Tszabeau]

What is/were the positions of the stars within the nebula?

[Psnarf]

A trench-faced homunculus? I've heard a politician described as a pig-faced homunculus, but that was in response to a "Doctor Who" episode (091 - The Talons Of Weng-Chiang).

[Chris Peterson]

" Between 1838 and 1845, Eta Carinae underwent the Great Eruption" - you mean, surely, " "Between 1838 and 1845, Eta Carinae was observed to undergo the Great Eruption" - the thing itself occurred thousands of years ago.

No, the usage in the caption is correct.

When discussing information carried at the speed of light, it is conventional and almost always reasonable to align the occurrence of an event with its observation. After all, you don't say "observed to undergo" before everything you see, even though everything is observed after it "really" happened.

[hlwelborn]

It looks like a bad heart valve.

[geckzilla]

(Mind you, the HST or JWST will no doubt offer better images online, than anything my scope could make from my suburban backyard.)

HST can't look at things that bright without the sensors becoming damaged. It would no doubt look at it once things calmed down, though.

[Chris Peterson]

HST can't look at things that bright without the sensors becoming damaged. It would no doubt look at it once things calmed down, though.

That's a bit of an urban myth. The only thing that HST can't look at without damaging its sensors is the Sun. It could certainly look at any supernova without damage. Whether its instruments would be scientifically useful for that task is a different question. We can get a wider range of measurements, as well as higher resolution from ground based telescopes.

[geckzilla]

If it is, then it's got some folks at STScI needlessly concerned. They used amateur astronomers to track the activity of cataclysmic variables to ensure they wouldn't be acting up while Hubble was observing them.
Edit: A link to fast forward to the point where Nolan is explaining the difficulties with Hubble's detectors: https://www.youtube.com/watch?feature=p ... L3L4#t=520

Click to play embedded YouTube video.

[JuanAustin]

can someone post an audio file saying "ETA CARINAE Homunculus" 3 times?? my tongue has cramp

[Chris Peterson]

If it is, then it's got some folks at STScI needlessly concerned. They used amateur astronomers to track the activity of cataclysmic variables to ensure they wouldn't be acting up while Hubble was observing them.

To be clear, this applies to one specific instrument, the COS, a near and far UV spectroscope which unlike other HST instruments, employs a photocathode and microchannel plate in front of the detector- elements that are prone to damage from too much light. There is nothing preventing the HST from pointing other instruments (in particular, imaging cameras) at a supernova, and simply avoiding the use of the COS.

[Boomer12k]

A 3d Printing of it would be cool....and then PAINT IN ALL THE DETAILS.....

:---[===] *

[geckzilla]

If it is, then it's got some folks at STScI needlessly concerned. They used amateur astronomers to track the activity of cataclysmic variables to ensure they wouldn't be acting up while Hubble was observing them.

To be clear, this applies to one specific instrument, the COS, a near and far UV spectroscope which unlike other HST instruments, employs a photocathode and microchannel plate in front of the detector- elements that are prone to damage from too much light. There is nothing preventing the HST from pointing other instruments (in particular, imaging cameras) at a supernova, and simply avoiding the use of the COS.

The video I linked to along with numerous mentions about not even wanting to point the telescope at Earth (probably the effects of which were also misunderstood and/or miscommunicated) got me under the impression a supernova (within our galaxy) could potentially damage the instruments. I emailed the archive help desk recently about something unrelated but remembered this thread at the end and asked about eta Carinae on the side. I got a response from Dorothy Fraquelli and she indeed did not seem concerned that HST would become damaged by it but that is because of internal safe guards built into the telescope which shut it down. So unless those fail, the telescope is supposedly safe. She also said the CCDs can be overexposed but it takes a while for the excess charge to bleed off, which would be pretty annoying if your observations happen after such an event (and it has happened, iirc)...

Of course, one wonders if it is also possible for something to be so bright that damage might occur before the safeties kick in. What would happen if Hubble looked at the sun? Nothing good I'm sure but I also can't help wondering. Sounds like a plot to a drama-filled soap opera revolving around astronomers.

[Chris Peterson]

The video I linked to along with numerous mentions about not even wanting to point the telescope at Earth (probably the effects of which were also misunderstood and/or miscommunicated) got me under the impression a supernova (within our galaxy) could potentially damage the instruments.

The HST can be, and has been pointed towards the Earth with its imaging CCDs active (for calibration purposes). Also, the Moon has been imaged (a tricky business that involved moving the spacecraft as the exposure was made).

I emailed the archive help desk recently about something unrelated but remembered this thread at the end and asked about eta Carinae on the side. I got a response from Dorothy Fraquelli and she indeed did not seem concerned that HST would become damaged by it but that is because of internal safe guards built into the telescope which shut it down. So unless those fail, the telescope is supposedly safe. She also said the CCDs can be overexposed but it takes a while for the excess charge to bleed off, which would be pretty annoying if your observations happen after such an event (and it has happened, iirc)...

The safeguards are presumably for the COS instrument, since the CCD cameras are not subject to damage from overexposure. Indeed, they are often deliberately overexposed in order to balance the excess charge trapped after normal exposures. This is called residual bulk image (RBI) and creates a ghost image that can last quite a while, messing up subsequent images if there was anything bright recently exposed. So there's a device that "flashes" the CCD, hitting it with bright light to erase the pattern in the RBI. The downside is that this slightly raises the noise level, but that's often preferably to some sort of pattern on the signal.

What would happen if Hubble looked at the sun?

Nearly instantaneous thermal damage. It would occur to internal elements other than the camera before the aiming was complete. That's why there is a strict protocol that forbids imaging anywhere near the Sun (I seem to remember that the safe zone is something like 45°, far more than it absolutely needs to be). Objects within that zone have to wait for a different time of year to be imaged.

[therodly1]

I suspect that this will turn out to be nothing but two stars that have collided.

[Chris Peterson]

I suspect that this will turn out to be nothing but two stars that have collided.

While there's no particular reason to make that assumption, the reality is that stars colliding is a vanishingly rare event, so an observation would be scientifically valuable.