APOD: Doomed Star Eta Carinae (2019 Feb 20)

[APOD Robot]

Doomed Star Eta Carinae

Explanation: Eta Carinae may be about to explode. But no one knows when - it may be next year, it may be one million years from now. Eta Carinae's mass - about 100 times greater than our Sun - makes it an excellent candidate for a full blown supernova. Historical records do show that about 170 years ago Eta Carinae underwent an unusual outburst that made it one of the brightest stars in the southern sky. Eta Carinae, in the Keyhole Nebula, is the only star currently thought to emit natural LASER light. This featured image brings out details in the unusual nebula that surrounds this rogue star. Diffraction spikes, caused by the telescope, are visible as bright multi-colored streaks emanating from Eta Carinae's center. Two distinct lobes of the Homunculus Nebula encompass the hot central region, while some strange radial streaks are visible in red extending toward the image right. The lobes are filled with lanes of gas and dust which absorb the blue and ultraviolet light emitted near the center. The streaks, however, remain unexplained.

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[FLPhotoCatcher]

"Eta Carinae may be about to explode. But no one knows when - it may be next year, it may be one million years from now."

What about this year? Are scientists able to rule that out?

[Boomer12k]

Red streaks... I am wondering if high velocity gas has "striated" dust and gas, and straightened those out. because there are other red areas and they seem to be light, or whatever colliding with them... it looks like colliding with the interstellar medium? or other debris... maybe a "first burst" of material... 170 years or even more in the past...
Go look at "Mythbuster paint explosion videos..." on youtube... especially "Explosive Art High-Speed"...you will see many striations before it diffuses...I think the red streaks are a part of the explosion... my guess...

:---[===] *

[heehaw]

This year? Reminds me of the fellow who told his son that a fossil in the museum was a million and three years old. His son asked how he knew that. He replied that three years ago the museum director had told him it was a million years old....

[Nitpicker]

I think the "next year" was recycled from 27-Dec-2015:
https://apod.nasa.gov/apod/ap151227.html

So, I think we can now rule out all of 2015 to 2018.

But it sure is a different image in today's APOD. Nice processing, geck.

[orin stepanek]

Did the Star create the keyhole? If so maybe that released enough eternal pressure to give Eta Carinae a little longer life span! Just guessing!

[Guest]

Wondering about the lobes. Do they correspond to the north and south magnetic poles of the star, and can the reveal anything about its rotation and anything about potential planets therein. Tho I suspect any such planets are 'french toast'. But the spin of the star is where my interest resides.

[neufer]

Wondering about the lobes. Do they correspond to the north and south magnetic poles of the star, and can the reveal anything about its rotation and anything about potential planets therein. Tho I suspect any such planets are 'french toast'. But the spin of the star is where my interest resides.

• The lobes are thought to correspond to the rotation axis of star that expelled them.
  However, it is not quite clear which of the two stars in the binary did the final expelling.

<<Eta Carinae is enclosed by, and lights up, the Homunculus Nebula, a small emission and reflection nebula composed mainly of gas ejected during the Great Eruption event in 1837, as well as dust that condensed from the debris. The nebula consists of two polar lobes aligned with the rotation axis of "the star," plus an equatorial "skirt". The mass of the lobes gives an accurate measure of the scale of the Great Eruption, with estimates ranging from 12–15 M_☉ up to as high as 40 M_☉. The material from the Great Eruption is strongly concentrated towards the poles; 75% of the mass and 90% of the kinetic energy were released above latitude 45°. Closer studies show many fine details: a Little Homunculus within the main nebula, probably formed by the 1890 eruption; a jet; fine streams and knots of material, especially noticeable in the skirt region; and three Weigelt Blobs—dense gas condensations very close to the star itself.>>

[MarkBour]

If we were to suppose that we had lots more data on stars that were massive and variable and producing pre-supernova nebulas, then it might be possible to give a rough prediction of when to expect Eta Carina to supernova. For a hypothetical example, suppose we had seen 100 Eta Carinas by now, in various stages, some of which had gone supernova. It might be that for a given size of star, say 150 M_☉, a pre-death two-lobed ejection is formed about 500 years before the finale, and it grows to about 4 light years end-to-end by the time the final blast occurs. (My numbers are absolutely "picked from a hat", just to make the idea concrete.)

I do find the light curve displayed at https://en.wikipedia.org/wiki/Eta_Carin ... _2014).png very intriguing. Doesn't it appear for the time being that Eta Carina is building up for another major event? Possibly in a few decades, or less?

[Tragic Astronomy]

"And the toursists take their tee-shirts off."

This is just one image in my video, Yawning or Snarling by The Tragically Hip. Here's the entire video.

https://www.youtube.com/watch?v=O5UCmrE ... k36QE&t=0s

[BDanielMayfield]

So are the pulsed rays coming out of this the natural lasers, or are they the diffraction spikes? My guess would be that they are the lasers (have never seen pulsed diffraction spikes) but just wish to make sure.

[Tragic Astronomy]

A great in depth video discussing The Amazing Eta Carinae from Sixty Symbols YouTube channel.

[seedsofearth]

If we could look directly along the axis of the homunculus and see the star(s) at its center, would it not appear similar to the Eskimo nebula or the Cat's Eye nebula? In other words, are they not all similar structures, but seen at varying angles?

[Astronymus]

If we could look directly along the axis of the homunculus and see the star(s) at its center, would it not appear similar to the Eskimo nebula or the Cat's Eye nebula? In other words, are they not all similar structures, but seen at varying angles?

This might interest you.

Click to play embedded YouTube video.

NASA | Scientists Create First Full 3D Model of Eta Carinae Nebula [/youtube]

[Chris Peterson]

So are the pulsed rays coming out of this the natural lasers, or are they the diffraction spikes? My guess would be that they are the lasers (have never seen pulsed diffraction spikes) but just wish to make sure.

All the straight, sharp lines are diffraction spikes. They look "pulsed" because of diffraction... different wavelengths present at different distances along the spike. The laser light produced isn't in visible beams, it just shows up as spikes in the UV spectrum.

[BDanielMayfield]

So are the pulsed rays coming out of this the natural lasers, or are they the diffraction spikes? My guess would be that they are the lasers (have never seen pulsed diffraction spikes) but just wish to make sure.

All the straight, sharp lines are diffraction spikes. They look "pulsed" because of diffraction... different wavelengths present at different distances along the spike. The laser light produced isn't in visible beams, it just shows up as spikes in the UV spectrum.

Thanks Chris. Low and behold, the very next APOD shows a very clear example of "pulsed" diffraction spikes.

[Chris Peterson]

So are the pulsed rays coming out of this the natural lasers, or are they the diffraction spikes? My guess would be that they are the lasers (have never seen pulsed diffraction spikes) but just wish to make sure.

All the straight, sharp lines are diffraction spikes. They look "pulsed" because of diffraction... different wavelengths present at different distances along the spike. The laser light produced isn't in visible beams, it just shows up as spikes in the UV spectrum.

Thanks Chris. Low and behold, the very next APOD shows a very clear example of "pulsed" diffraction spikes. :bang: :facepalm: :lol2:

If you have an RGB image, the spikes cycle through the spectrum. If you image through narrowband filters, however, much of that spectrum will be blocked, so you'll just see brightness peaks along the spikes. That is, sometimes the spikes will look like rainbows, and other times they'll look "pulsed".