APOD: Eta Carinae and the Expanding Nebula... (2014 Dec 02)

[APOD Robot]

Eta Carinae and the Expanding Homunculus Nebula

Explanation: How did the Eta Carinae star system create this unusual expanding nebula? No one knows for sure. About 170 years ago, the southern star system Eta Carinae (Eta Car) mysteriously became the second brightest star system in the night sky. Twenty years later, after ejecting more mass than our Sun, Eta Car unexpectedly faded. Somehow, this outburst appears to have created the Homunculus Nebula. The three-frame video features images of the nebula taken by the Hubble Space Telescope in 1995, 2001, and 2008. The Homonculus nebula's center is lit by light from a bright central star, while the surrounding regions are expanding lobes of gas laced with filaments of dark dust. Jets bisect the lobes emanating from the central stars. Expanding debris includes streaming whiskers and bow shocks caused by collisions with previously existing material. Eta Car still undergoes unexpected outbursts, and its high mass and volatility make it a candidate to explode in a spectacular supernova sometime in the next few million years.

<< Previous APOD

This Day in APOD

Next APOD >>

[/b]

[Ann]

Interesting image. Thanks.

Does the Homunculus Nebula expand faster or slower than the Crab Nebula?

Ann

[Lithopsian]

The Crab Nebula is expanding faster, around twice as fast. However, it is much larger and older (and more massive) and the expansion is not visible on the scale or timescale shown in this animation. The Crab Nebular was a fullblown supernova, more violent even than the eta Carinae eruption.

[star struk]

Eta Carina picture shows lines arranged in a hexagon pattern from star. Are these the 'whiskers' refered to in picture description? The lines do not appear to be an artifact of instrumentation; their orientation changes through the series of images over time but the hexagonal character basically remains the same. The stream of lines probably is related to the equatorial structure of the star itself or a ring of fire extending across the star equator. Truly amazing.
If and when Eta Carina goes bust all life forms inhabiting stellar systems approximately 300 LY from EC will be seriously effected or even decimated by the high energy particles and radiation. An Eta Carina supernova will be observable on Earth in day light and cast a shadow at night. The high energy radiation will not affect life on Earth or Mars, but the debris of the nova will reach the Solar System neighborhood in due time. Nothing to worry about. But, with so many nova remnants littering the sky an in depth study of nebular matter may be recommended. Recall the story of the Cygnus mystery in which radiation from the star in Cygnus was detected in an ancient cave.

[geckzilla]

Eta Carina picture shows lines arranged in a hexagon pattern from star. Are these the 'whiskers' refered to in picture description?

The six lines which change orientation in one of the three frames of the animation are artifacts. They include the usual x-shaped diffraction pattern created by the struts holding up Hubble's secondary mirror and then one line bisecting them which is a charge bleed caused by electrons overflowing in the detector itself due to the extreme brightness of the star.

Diffraction spikes and charge bleed.

BTW, here is the animation on a forever loop that won't stop after only 5 plays.
http://www.geckzilla.com/astro/CarinaEx ... orever.gif

[Ann]

Thanks, Geck!

Ann

[Coil_Smoke]

its high mass and volatility make it a candidate to explode in a spectacular supernova sometime in the next few million years.

This already seems like a nova event.

[Chris Peterson]

its high mass and volatility make it a candidate to explode in a spectacular supernova sometime in the next few million years.

This already seems like a nova event.

Nope. It was neither a nova nor a supernova. (Say that three times quickly.)

[Ann]

An interesting possibility is that the 1843 event might have been a supernova impostor. If so, it is just possible that Eta Carina blew off so much of itself during those 19th century outbursts that it will not be as brilliant as we might expect it to be when it goes supernova for real.

Ann

[starsurfer]

Doesn't the Homunculus Nebula also have outer parts that are only visible in xray?

Also isn't the central illuminating star Eta Carinae?

[LocalColor]

The more data we gather the more we learn. I like the 3 photo "video" very much. Thanks again APOD.

[Chris Peterson]

Doesn't the Homunculus Nebula also have outer parts that are only visible in xray?

Yes, there is a much larger region of very hot ejecta that radiates in soft x-rays but is too tenuous to produce significant signal in the visible spectrum (as well as central structure visible in hard x-rays).

Also isn't the central illuminating star Eta Carinae?

Yes, and the Homunculus nebula itself is primarily a reflection nebula. But it's embedded in the Eta Carina nebula, which is primarily an emission nebula (with regions of reflection).

[ChrisNW]

Is Eta Carinae a binary system?

http://www.nasa.gov/home/hqnews/2005/no ... _star.html

[Chris Peterson]

Is Eta Carinae a binary system?

At the least.

[ChrisNW]

Cool, it could be more! By far this is my fav star from APOD.

[Boomer12k]

Ought to make a nice remnant....hope somebody is around to study it....
Maybe Cats will be the dominant intelligent species then....Planet of the Cats...

:---[===] *

[hoohaw]

You may remember my question of a few days ago, wondering why we humans find almost all astronomical photos BEAUTIFUL; why, why, from an evolutionary point of view? I said "almost all," and one exception I was thinking of was this very Eta Carinae nebula, which looks like something out of a Medical Pathology Illustrated volume. It looks disgusting! (Again, why? why? and what is beauty?)

[Chris Peterson]

You may remember my question of a few days ago, wondering why we humans find almost all astronomical photos BEAUTIFUL; why, why, from an evolutionary point of view?

The question made no sense to me. Why should it matter from an evolutionary point of view? Our visual aesthetics are based on aspects of color and form, which are universal. We did not evolve the concept of beauty around just those things that were present in our environment.

[geckzilla]

It's beautiful because it's far away, colorful, hard enough to understand that it is practically magical, and not crossing anyone's perceived borders. If nebulas had a habit of making little webs in the corners of houses or had little biting fangs, they'd be as maligned as spiders, which are often every bit as beautiful if not even more so.

[hoohaw]

You may remember my question of a few days ago, wondering why we humans find almost all astronomical photos BEAUTIFUL; why, why, from an evolutionary point of view?

The question made no sense to me. Why should it matter from an evolutionary point of view? Our visual aesthetics are based on aspects of color and form, which are universal. We did not evolve the concept of beauty around just those things that were present in our environment.

http://en.wikipedia.org/wiki/Beauty is interesting to read. Is beauty a universal? We, and the flying insects, agree on the "beauty" of the flowers. Is there a mathematics of beauty? Symmetry? But where is symmetry in photos of the interstellar medium?

[Ann]

Chris wrote:
Yes, and the Homunculus nebula itself is primarily a reflection nebula. But it's embedded in the Eta Carina nebula, which is primarily an emission nebula (with regions of reflection).

The main component of the binary (or perhaps multiple) star Eta Carina is much too cool to ionize an emission nebula. The second component may be hot enough to do the trick.

Of course, the colliding winds of this nebula might certainly cause any hydrogen in the vicinity to glow red.

Ann

[montylc2001]

What is Eta Carinae's proper motion in relation to Sol? If it is moving away at a relatively high speed from us then in a few million years when it goes supernova it may be on the other side of the galaxy and not visible to Earth.

[Chris Peterson]

What is Eta Carinae's proper motion in relation to Sol? If it is moving away at a relatively high speed from us then in a few million years when it goes supernova it may be on the other side of the galaxy and not visible to Earth.

Radially, it is moving towards us at 25 km/s.

[DoppelBungle]

What is Eta Carinae's proper motion in relation to Sol? If it is moving away at a relatively high speed from us then in a few million years when it goes supernova it may be on the other side of the galaxy and not visible to Earth.

Radially, it is moving towards us at 25 km/s.

Lucky for us it'll be 95 million years before it gets here

[Chris Peterson]

What is Eta Carinae's proper motion in relation to Sol? If it is moving away at a relatively high speed from us then in a few million years when it goes supernova it may be on the other side of the galaxy and not visible to Earth.

Radially, it is moving towards us at 25 km/s.

Lucky for us it'll be 95 million years before it gets here :wink:

At least. There's a tangential component, too, which I don't know the value of. But it's possible that in 95 million years it will be farther away from us than it is now.