APOD: Eta Car: 3D Model of the Most Star... (2022 Feb 09)

[APOD Robot]

Eta Car: 3D Model of the Most Dangerous Star Known

Explanation: What's the most dangerous star near earth? Many believe it's Eta Carinae, a binary star system about 100 times the mass of the Sun, just 10,000 light years from earth. Eta Carinae is a ticking time bomb, set to explode as a supernova in only a few million years, when it may bathe the earth in dangerous gamma rays. The star suffered a notorious outburst in the 1840s when it became the brightest star in the southern sky, only to fade to obscurity within decades. The star was not destroyed, but lies hidden behind a thick, expanding, double-lobed structure called the Homunculus which now surrounds the binary. Studies of this ejecta provide forensic clues about the explosion. Using observations from NASA satellites we can now visualize the 3D distribution of the shrapnel, all the way from the infrared, through optical and UV, to the outermost shell of million-degree material, visible only in X-rays.

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[andyjs]

I wonder which direction do we see eta carinae from. Are we looking down on one of the nodes or towards the middle?

[XgeoX]

I wonder which direction do we see eta carinae from. Are we looking down on one of the nodes or towards the middle?

We are looking more or less towards the middle (the actual stars of the system can’t be imaged behind all the dust.)
The slightly larger looking brighter lobe is closer to Earth (it’s the “bottom” one in the photo and video though of course up and down are meaningless in space.) It’s closer than the stars are to earth. The darker lobe lies further away from Earth than the system stars do.

[Ann]

Eta Carina shows similarities with a supernova impostor. ( ͡° ͜ʖ ͡°)

Wikipedia wrote:

Supernova impostors are stellar explosions that appear at first to be a 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).

Eta Carina underwent a series of spectacular brightenings in the 19th century. Even more spectacular was the supernova impostor of 2004 in galaxy UGC 4904, which exploded as a true supernova, SN 2006jc, in 2006, only two years after its first great outburst.

Swift Ultraviolet/Optical Telescope image of Supernova 2006jc in the galaxy UGC 4904 in three filters. Image: NASA/Swift/S. Immler.

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Wikipedia wrote about SN 2006jc:

SN 2006jc was a supernova that was detected on October 9, 2006 in the galaxy UGC 4904, which is about 77 million light-years away in the constellation Lynx. It was first seen by Japanese amateur astronomer Koichi Itagaki, American amateur Tim Puckett and Italian amateur Roberto Gorelli. Two years earlier, the progenitor star produced a supernova impostor that was detected by Itagaki. This outburst was apparently the progenitor star shedding its outer layers. When the star exploded in 2006, the shockwave hit the material blown off in 2004, heating it to millions of degrees and emitting copious amounts of X-rays.

So SN 2006jc exploded twice, in 2004 and 2006, except it was only in 2006 that it exploded for real and blew itself to smithereens!

A. Pastorello et.al. wrote in an article in Nature in 2007, A giant outburst two years before the core­ collapse of a massive star:

Here we report that the peculiar Type Ib supernova SN2006jc is spatially coincident with a bright optical transient that occurred in 2004. Spectroscopic and photometric monitoring of the supernova leads us to suggest that the progenitor was a carbon­ oxygen Wolf­-Rayet star embedded within a helium-­rich circumstellar medium. There are different possible explanations for this pre­explosion transient. It appears similar to the giant outbursts of Luminous Blue Variables (LBV) of 60­-100 solar mass (M_⊙) stars, however the progenitor of SN2006jc was helium and hydrogen deficient. An LBV­-like outburst of a Wolf-Rayet star could be invoked, but this would be the first observational evidence of such a phenomenon. Alternatively a massive binary system composed of an LBV which erupted in 2004, and a Wolf­-Rayet star exploding as SN2006jc, could explain the observations.

Ann

[Andyjs]

That makes sense. Thanks for your reply

[bystander]

A Tour of Eta Carinae

Click to play embedded YouTube video.

[orin stepanek]

Amazing Star:--- Glad we're out of harms way!
Plenty of other dangers to Mother Earth!

Kitty gonna get a drink; or a dunking!

[Fred the Cat]

A Tour of Eta Carinae

Click to play embedded YouTube video.

Streaks explained in both bystander's and Orin's posts
Hubblesite. org
"These streaks are created when the star's light rays poke through the dust clumps scattered along the bubble's surface. Wherever the ultraviolet light strikes the dense dust, it leaves a long, thin shadow that extends beyond the lobe into the surrounding gas. Eta Carinae resides 7,500 light-years away.Jul 1, 2019
Color Info: These images are a composite of s...
Dimensions: Image is about 45 arcseconds ac...
Distance: 7,500 light-years away from Earth

Eta Carinae: Observations in UV Light Uncover Magnesium ..."

[De58te]

I am a bit puzzled. Today's APOD description seems to imply that the most dangerous star near Earth is Eta Carinae at 10,000 ly. Yet the very link to "dangerous star near Earth" states that the closest Supernova stars to Earth are IK Pegasi B at 150 light years and Betelgeuse at about 600 ly. Yet the article goes on to say that NASA has determined that a supernova has to be within 50 ly to affect life on Earth? Seems that Eta Carinae is a bit farther away than 50 ly.

I would think that the most dangerous star closest to the Earth would be the Sun. I have read articles that a direct hit from a CME from the Sun could knock out satellites and be a death threat to astronauts on the space station. And a really big Carrington event today can knock out country wide electrical grids for months which in today's technological dependence on electrical power would mean no home lights and heating and no delivery and refrigeration of food for months. How many of you have food supplies to last for months? It would be the dark ages.

[Ann]

I am a bit puzzled. Today's APOD description seems to imply that the most dangerous star near Earth is Eta Carinae at 10,000 ly. Yet the very link to "dangerous star near Earth" states that the closest Supernova stars to Earth are IK Pegasi B at 150 light years and Betelgeuse at about 600 ly. Yet the article goes on to say that NASA has determined that a supernova has to be within 50 ly to affect life on Earth? Seems that Eta Carinae is a bit farther away than 50 ly.

I would think that the most dangerous star closest to the Earth would be the Sun. I have read articles that a direct hit from a CME from the Sun could knock out satellites and be a death threat to astronauts on the space station. And a really big Carrington event today can knock out country wide electrical grids for months which in today's technological dependence on electrical power would mean no home lights and heating and no delivery and refrigeration of food for months. How many of you have food supplies to last for months? It would be the dark ages.

Eta Carina isn't dangerous to the Earth, because it is too far away. We have also reason to believe that if it goes supernova and launches a tremendous jet, the jet will not be aimed at us, because we see the Homunculus Nebula of Eta Car at an angle.

A potentially much more dangerous star is WR star Wolf-Rayet 104:

Wolf-Rayet star WR 104. NASA/Keck Telescope.

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Wikipedia wrote about WR 104:

The WR star is surrounded by a distinctive spiral Wolf–Rayet nebula, often referred to as a pinwheel nebula. The rotational axis of the binary system, and likely of the two closest stars, is directed approximately towards Earth. Within the next few hundred thousand years, the Wolf–Rayet star is predicted to probably become a core-collapse-supernova with a small chance of producing a long duration gamma-ray burst.

The possibility of a supernova explosion from WR 104 having destructive consequences for life on Earth stirred interest in the mass media, and several popular science articles have been issued in the press since 2008. Some articles decide to reject the catastrophic scenario, while others leave it as an open question. Scientists currently believe the odds of WR 104 posing a risk to be small.

Ann