Starship Asterisk*

Ron-Astro Pharmacist wrote:

neufer wrote:

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ddanbe wrote:
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

https://en.wikipedia.org/wiki/Eta_Carinae#Possible_effects_on_Earth wrote:
<<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.>>

Chris Peterson wrote:

geckzilla wrote:

Chris Peterson wrote: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.

captainwiggins48 wrote:
Is it a 'given' that a photon can survive unperturbed, at a constant speed for 7,000 or 7 billion years?

https://en.wikipedia.org/wiki/Lyman-alpha_forest wrote:

[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 wrote:

Chris Peterson wrote:Not likely.

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

geckzilla wrote:

Glima49 wrote: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 wrote:Not likely.

geckzilla wrote:

Glima49 wrote: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...

Glima49 wrote:I can't wait for Betelgeuse, Eta Carinae or Sher 25 to either outburst dramatically again or blow up in a supernova.

Glima49 wrote:
I noticed in the light curve that around 1940 Eta Carinae experienced another brightening that continues to this day. Wonder if this means another Great Eruption? In any case, I can't wait for Betelgeuse, Eta Carinae or Sher 25 to either outburst dramatically again or blow up in a supernova.

• Then try saying their names 3 times in a row.

http://beetlejuice.wikia.com/wiki/Betelgeuse wrote:
<<Betelgeuse (better known as Beetlejuice) is a trickster and mischievous ghost who can be summoned if his name is said 3 times in a row. According to Betelgeuse, he attended Julliard, is a graduate of the Harvard Business School, traveled quite extensively, lived through the Black Plague (and had a pretty good time during that), and has seen The Exorcist about 167 times (AND IT KEEPS GETTING FUNNIER EVERY SINGLE TIME).

captainwiggins48 wrote:Until the nomenclature specifies the time evolution of events ("light year" may be archaic) we'll have to continually be mindful of local versus ancient 'time'.

captainwiggins48 wrote:

geckzilla wrote:Heh, I dunno why people get so caught up on using local time to describe when astronomical events occur. I mean, I get why, but at the same time, it's a given that distant objects have a noticeable light travel time. Mentioning it over and over is just redundant.

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

How did it get here seemingly under it's own power and where does it get it's sustainability? This question [sic] needs to be addressed, but I fear that many in the scientific community aren't ready for the answer.

geckzilla wrote:Heh, I dunno why people get so caught up on using local time to describe when astronomical events occur. I mean, I get why, but at the same time, it's a given that distant objects have a noticeable light travel time. Mentioning it over and over is just redundant.

neufer wrote:

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ddanbe wrote:
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

winstond wrote:

• Why does everyone seem so cranky today?
  Chill and enjoy the image folks, 'tis the season of goodwill.

• A few years ago, while visiting or, rather, rummaging about Notre-Dame, the author of this book found, in an obscure nook of one of the towers, the following word, engraved by hand upon the wall:--

• These Greek capitals, black with age, and quite deeply graven in the stone, with I know not what signs peculiar to Gothic caligraphy imprinted upon their forms and upon their attitudes, as though with the purpose of revealing that it had been a hand of the Middle Ages which had inscribed them there, and especially the fatal & melancholy meaning contained in them, struck the author deeply. He questioned himself; he sought to divine who could have been that soul in torment which had not been willing to quit this world without leaving this stigma of crime or unhappiness upon the brow of the ancient church. Afterwards, the wall was whitewashed or scraped down, I know not which, and the inscription disappeared. For it is thus that people have been in the habit of proceeding with the marvellous churches of the Middle Ages for the last two hundred years. Mutilations come to them from every quarter, from within as well as from without. The priest whitewashes them, the archdeacon scrapes them down; then the populace arrives and demolishes them.

ddanbe wrote:
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

Chris Peterson wrote:

bjmb wrote:

Historical records do show that about 150 years ago Eta Carinae underwent an unusual outburst that made it one of the brightest stars in the southern sky.

you mean to say: "Historical records do show that about 150 years ago Eta Carinae was noticed to have undergone an unusual outburst that made it one of the brightest stars in the southern sky."

I prefer the first, as a shorter and clearer statement of what occurred.