APOD: Doomed Star Eta Carinae (2015 Dec 27)

[DavidLeodis]

In the explanation it states the image was "taken in 1996" but in the information in the related Hubble NewsCenter release (including its Fast Facts) it states the exposure was in September 1995 (the image was however released on June 10 1996).

[geckzilla]

I can't wait for Betelgeuse, Eta Carinae or Sher 25 to either outburst dramatically again or blow up in a supernova.

Heh, an Eta Carinae supernova would bake Earth's little DNA creatures to a light crisp, but sure, let's have a watch...

[Chris Peterson]

I can't wait for Betelgeuse, Eta Carinae or Sher 25 to either outburst dramatically again or blow up in a supernova.

Heh, an Eta Carinae supernova would bake Earth's little DNA creatures to a light crisp, but sure, let's have a watch...

Not likely.

[geckzilla]

Not likely.

Not likely what? That it will happen soon or that it will do some damage to our DNA?

[Glima49]

I can't wait for Betelgeuse, Eta Carinae or Sher 25 to either outburst dramatically again or blow up in a supernova.

Heh, an Eta Carinae supernova would bake Earth's little DNA creatures to a light crisp, but sure, let's have a watch...

Maybe go to a binary nova star that freaks me out: IK Pegasi, only 150 light years away, on the verge of exploding as a Type Ia supernova! Anyways, back to the topic. Eta Carinae really fascinates me. One of the most massive and luminous stars in the galaxy known. I wonder what would really happen...

[Chris Peterson]

Not likely.

Not likely what? That it will happen soon or that it will do some damage to our DNA?

Not likely that a supernova of Eta Carina would result in any significant problems on Earth. Because it probably wouldn't produce a GRB. And if it did, the odds are strongly against it hitting us. And even if it did hit us, at 7500 ly it would be unlikely to have much impact. So all in all, not much of a concern.

Not to mention that it probably won't happen for at least a few thousand years, by which point we ourselves might have baked away Earth's little DNA creatures to more than a light crisp.

[neufer]

Is it a 'given' that a photon can survive unperturbed, at a constant speed for 7,000 or 7 billion years?

All photons are subjected wavelength redshift expansion due to the expansion of the Universe.

In addition, 7 billion year old UV photons with initial wavelengths between 668 - 1216 Å might pass through a neutral hydrogen cloud in the intergalactic medium at just the point when they were sufficiently redshifted to be absorbed by the strong 1216 Å Lyman-alpha transition. Photons with redshifted wavelengths > 1216 Å that have successfully passed through this gauntlet of neutral hydrogen intergalactic clouds display a battle scarred "Lyman-alpha forest" spectra.

[b][color=#0000FF][size=135]Lyman-alpha forest in the observed spectrum of a quasar[/size][/color][/b]

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<<In astronomical spectroscopy, the Lyman-alpha forest is a series of absorption lines in the spectra of distant galaxies and quasars arising from the Lyman-alpha electron transition of the neutral hydrogen atom.

The Lyman-alpha transition corresponds to an electron transitioning between the ground state (n=1) and the first excited state (n=2). The Lyman-alpha spectral line has a laboratory, or rest, wavelength of 1216 Å, which is in the ultraviolet portion of the electromagnetic spectrum.

The Lyman-alpha absorption lines in the quasar spectra result from intergalactic gas through which the galaxy or quasar's light has traveled. Since neutral hydrogen clouds in the intergalactic medium are at different degrees of redshift (due to their varying distance from Earth), their absorption lines are observed at a range of wavelengths. Each individual cloud leaves its fingerprint as an absorption line at a different position in the observed spectrum.

The Lyman-alpha forest is an important probe of the intergalactic medium and can be used to determine the frequency and density of clouds containing neutral hydrogen, as well as their temperature. Searching for lines from other elements like helium, carbon and silicon (matching in redshift), the abundance of heavier elements in the clouds can also be studied. A cloud with a high column density of neutral hydrogen will show typical damping wings around the line and is referred to as a damped Lyman-alpha system.

For quasars at higher redshift the number of lines in the forest is higher, until at a redshift of about 6, there is so much neutral hydrogen in the intergalactic medium that the forest turns into a Gunn-Peterson trough. This shows the end of the reionization of the universe. The Lyman-alpha forest observations can be used to constrain cosmological models.>>

[geckzilla]

Not likely.

Not likely what? That it will happen soon or that it will do some damage to our DNA?

Not likely that a supernova of Eta Carina would result in any significant problems on Earth. Because it probably wouldn't produce a GRB. And if it did, the odds are strongly against it hitting us. And even if it did hit us, at 7500 ly it would be unlikely to have much impact. So all in all, not much of a concern.

Not to mention that it probably won't happen for at least a few thousand years, by which point we ourselves might have baked away Earth's little DNA creatures to more than a light crisp.

I didn't mean major problems, but I guess "light crisp" doesn't mean much. I wouldn't want to look at it or bask in its light for more than a few moments just to be sure, though. I've heard other astronomers express some mild concern about the event if it were to happen soon.

[neufer]

<<At 7,500 light years from [Eta Carinae] it is unlikely to directly affect terrestrial lifeforms, as they will be protected from gamma rays by the atmosphere and from some other cosmic rays by the magnetosphere. The main damage would be restricted to the upper atmosphere, the ozone layer, spacecraft, including satellites, and any astronauts in space.

Eta Carinae is not expected to produce a gamma-ray burst and its axis is not currently aimed near Earth, but a direct hit from a gamma-ray burst could cause catastrophic damage and a major extinction event. Calculations show that the deposited energy of such a gamma-ray burst striking the Earth's atmosphere would be equivalent to one kiloton of TNT per square kilometer over the entire hemisphere facing the star, with ionizing radiation depositing ten times the lethal whole body dose to the surface.>>

[Beyond]

Well, 'that' is certainly a cheery scenario.

[ta152h0]

was he the guy that tricked Mr Apod into thinking Betelgeuse blew up recently ?

[Ron-Astro Pharmacist]

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I find it a strange coincidence that the nebula around this star resembles one of the d-orbitals of an atom.
Anyone any comments?

• It is the classical shape
  of an axially symmetric
  quadrupole moment

Does anyone know what shape is represented if you subtract a torus from a sphere? To me it would be shaped liked a wormhole plus a little left over (as the remainder of the sphere). Of course there are many torus-shapes but" in general" I'm asking is there a named geometrical shape for the part that is not the torus

That shape might be close to this? Surrounds it anyways. Wish I knew more about spaces.

https://simple.wikipedia.org/wiki/Higgs_field