APOD: The Cave Nebula in Hydrogen, Oxygen,... (2018 Nov 14)

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APOD: The Cave Nebula in Hydrogen, Oxygen,... (2018 Nov 14)

Post by APOD Robot » Wed Nov 14, 2018 5:11 am

Image The Cave Nebula in Hydrogen, Oxygen, and Sulfur

Explanation: What's inside this cosmic cave? A stellar nursery 10 light-years deep. The featured skyscape is dominated by dusty Sh2-155, the Cave Nebula. In the telescopic image, data taken through a narrowband filters tracks the nebular glow of hydrogen, oxygen, and sulfur, colors that together form the Hubble Palette. About 2,400 light-years away, the scene lies along the plane of our Milky Way Galaxy toward the royal northern constellation of Cepheus. Astronomical explorations of the region reveal that it has formed at the boundary of the massive Cepheus B molecular cloud and the hot, young stars of the Cepheus OB 3 association. The bright rim of ionized hydrogen gas is energized by radiation from the hot stars, dominated by the bright star just to the left of the cave entrance. Radiation driven ionization fronts are likely triggering collapsing cores and new star formation within.

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Re: APOD: The Cave Nebula in Hydrogen, Oxygen,... (2018 Nov 14)

Post by Boomer12k » Wed Nov 14, 2018 7:08 am

Oooooo nice blues...

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The curly pig tail dark nebula

Post by neufer » Wed Nov 14, 2018 1:09 pm

https://www.themystica.com/eleusinian-mysteries/ wrote:
<<Within the Eleusinian Mysteries the role of Demeter is vitally important.
She took her name from Mother Earth, as was among the generation of children born of Cronus and Rhea.

Only Demeter, and Hekate, a moon goddess, heard her daughter, Persephone, scream for help when the Earth opened permitting Hades to snatch her away. But when bereaved Demeter tried tracing her daughter’s footsteps she found them obliterated by those of a pig. When the chasm opened to swallow up Persephone, the pigs fell in as well. This is, according to tradition, the reason that pigs play an important role in the rites of Demeter and Persephone. :arrow:

The first festivals celebrating the sorrows and later joys of Demeter and Persephone were exclusively for women held in pre-Hellenic Greece; that is in the so-called Pelasgian period, when the hieratic civilizations of Crete and Troy were at their zenith before the time of the warrior-gods Zeus and Apollo who reduced the power of the great goddess. The festivals included the sacrifice of suckling pigs in a manner suggestive of human sacrifice.

The seed-time festival of Thesmophoria lasted three days, the first day being named Kathodos (downgoing) and Anodos (upcoming), the second Nestia (fasting), and the last Kalligeneia(fair-born or fair-birth); and it was during the first that the suckling pigs were thrown, probably alive, into an underground chamber called a megara, and left there to rot for a year, the bones from the year before being carried up to the earth again and placed upon an altar.>>
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Re: APOD: The Cave Nebula in Hydrogen, Oxygen,... (2018 Nov 14)

Post by Rules For » Wed Nov 14, 2018 3:46 pm

I understand the logic behind using a hydrogen-alpha filter, but could someone explain to me the logic behind using oxygen and sulfur filters, as opposed to using some other elemental filters? And are those filters centered on specific wavelengths, ala hydrogen-alpha (e.g. sulfur-alpha, or something)?

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Re: The curly pig tail dark nebula

Post by Ann » Wed Nov 14, 2018 3:46 pm

neufer wrote:
Wed Nov 14, 2018 1:09 pm

The first festivals celebrating the sorrows and later joys of Demeter and Persephone were exclusively for women held in pre-Hellenic Greece; that is in the so-called Pelasgian period, when the hieratic civilizations of Crete and Troy were at their zenith before the time of the warrior-gods Zeus and Apollo who reduced the power of the great goddess. The festivals included the sacrifice of suckling pigs in a manner suggestive of human sacrifice.

The seed-time festival of Thesmophoria lasted three days, the first day being named Kathodos (downgoing) and Anodos (upcoming), the second Nestia (fasting), and the last Kalligeneia(fair-born or fair-birth); and it was during the first that the suckling pigs were thrown, probably alive, into an underground chamber called a megara, and left there to rot for a year, the bones from the year before being carried up to the earth again and placed upon an altar.>>

And the innocent Cave Nebula has nothing to do with such horridness. :evil:

Thanks for the picture you posted, though. It was good! :D

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Re: APOD: The Cave Nebula in Hydrogen, Oxygen,... (2018 Nov 14)

Post by neufer » Wed Nov 14, 2018 4:48 pm

Rules For wrote:
Wed Nov 14, 2018 3:46 pm

I understand the logic behind using a hydrogen-alpha filter, but could someone explain to me the logic behind using oxygen and sulfur filters, as opposed to using some other elemental filters? And are those filters centered on specific wavelengths, ala hydrogen-alpha (e.g. sulfur-alpha, or something)?
https://en.wikipedia.org/wiki/Forbidden_mechanism wrote:
<<In spectroscopy, a forbidden line is a spectral line associated with absorption or emission of light by atomic nuclei, atoms, or molecules which undergo a transition that is not allowed by a particular selection rule but is allowed if the approximation associated with that rule is not made. For example, in a situation where, according to usual approximations (such as the electric-dipole approximation for the interaction with light), the process cannot happen, but at a higher level of approximation (e.g. magnetic dipole, or electric quadrupole) the process is allowed but at a much lower rate. An example is phosphorescent glow in the dark materials, which absorb light and form an excited state whose decay involves a spin flip, and is therefore forbidden by electric dipole transitions. The result is emission of light slowly over minutes or hours.

Forbidden emission lines have been observed in extremely low-density gases and plasmas, either in outer space or in the extreme upper atmosphere of the Earth. In space environments, densities may be only a few atoms per cubic centimetre, making atomic collisions unlikely. Under such conditions, once an atom or molecule has been excited for any reason into a meta-stable state, then it is almost certain to decay by emitting a forbidden-line photon. Since meta-stable states are rather common, forbidden transitions account for a significant percentage of the photons emitted by the ultra-low density gas in space.

Forbidden lines of nitrogen ([N II] at 654.8 and 658.4 nm), sulfur ([SII] at 671.6 and 673.1 nm), and oxygen ([O II] at 372.7 nm, and [O III] at 495.9 and 500.7 nm) are commonly observed in astrophysical plasmas. These lines are important to the energy balance of planetary nebulae and H II regions. The forbidden 21-cm hydrogen line is particularly important for radio astronomy as it allows very cold neutral hydrogen gas to be seen. Also, the presence of [O I] and [SII] forbidden lines in the spectra of T-tauri stars implies low gas density. (Forbidden line transitions are noted by placing square brackets around the atomic or molecular species in question, e.g. [O III] or [SII].)>>
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Re: The curly pig tail dark nebula

Post by neufer » Wed Nov 14, 2018 4:58 pm

Click to play embedded YouTube video.
Lisa wrote:
Wed Nov 14, 2018 3:46 pm
neufer wrote:
Wed Nov 14, 2018 1:09 pm

The first festivals celebrating the sorrows and later joys of Demeter and Persephone were exclusively for women held in pre-Hellenic Greece; the festivals included the sacrifice of suckling pigs in a manner suggestive of human sacrifice. The suckling pigs were thrown, probably alive, into an underground chamber called a megara, and left there to rot for a year, the bones from the year before being carried up to the earth again and placed upon an altar.>>
And the innocent Cave Nebula has nothing to do with such horridness. :evil:
I'm sure the suckling pigs were still good (eating) after a year.
Art Neuendorffer

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Ann
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Re: The curly pig tail dark nebula

Post by Ann » Wed Nov 14, 2018 6:39 pm

neufer wrote:
Wed Nov 14, 2018 4:58 pm
Click to play embedded YouTube video.
Lisa wrote:
Wed Nov 14, 2018 3:46 pm
neufer wrote:
Wed Nov 14, 2018 1:09 pm

The first festivals celebrating the sorrows and later joys of Demeter and Persephone were exclusively for women held in pre-Hellenic Greece; the festivals included the sacrifice of suckling pigs in a manner suggestive of human sacrifice. The suckling pigs were thrown, probably alive, into an underground chamber called a megara, and left there to rot for a year, the bones from the year before being carried up to the earth again and placed upon an altar.>>
And the innocent Cave Nebula has nothing to do with such horridness. :evil:
I'm sure the suckling pigs were still good (eating) after a year.
Drawing of me by Valentina4940.

My aversion to the color cyan is well known in various realms and universes. So in my Lisa cartoon incarnation (depiction?), I am angry at the cyan cave!

Maybe there are pink little piglets in there, or rotting corpses of them?

Ann
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Re: The curly pig tail dark nebula

Post by sytheblackwolfe » Wed Nov 14, 2018 7:12 pm

neufer wrote:
Wed Nov 14, 2018 4:58 pm
Click to play embedded YouTube video.
Lisa wrote:
Wed Nov 14, 2018 3:46 pm
neufer wrote:
Wed Nov 14, 2018 1:09 pm

The first festivals celebrating the sorrows and later joys of Demeter and Persephone were exclusively for women held in pre-Hellenic Greece; the festivals included the sacrifice of suckling pigs in a manner suggestive of human sacrifice. The suckling pigs were thrown, probably alive, into an underground chamber called a megara, and left there to rot for a year, the bones from the year before being carried up to the earth again and placed upon an altar.>>
And the innocent Cave Nebula has nothing to do with such horridness. :evil:
I'm sure the suckling pigs were still good (eating) after a year.
I doubt they themselves were good eating, but they supposedly led to a better crop - or so I've read somewhere.

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Ann
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Re: The curly pig tail dark nebula

Post by Ann » Wed Nov 14, 2018 7:20 pm

sytheblackwolfe wrote:
Wed Nov 14, 2018 7:12 pm
neufer wrote:
Wed Nov 14, 2018 4:58 pm
Click to play embedded YouTube video.
Lisa wrote:
Wed Nov 14, 2018 3:46 pm

And the innocent Cave Nebula has nothing to do with such horridness. :evil:
I'm sure the suckling pigs were still good (eating) after a year.
I doubt they themselves were good eating, but they supposedly led to a better crop - or so I've read somewhere.
I don't know about good eating, but I have definitely heard about good drinking.

Long ago, a colleague of mine claimed to have been told, during her visit to Spain, that the wine in one of the vats in one Spanish village turned out to be particularly delicious. Later, during the cleaning of the vats, the body of a missing vineyard worker was found in the vat that had produced the superior wine. Nowadays, my colleague said, vineyard workers are not sacrificed in order to make splendid wine, but instead a large ham is placed in each of the vats, to give the maturing wine the "body" it needs!

Ann
Last edited by Ann on Thu Nov 15, 2018 4:45 am, edited 1 time in total.
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neufer
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I'll drown you in the malmsey-butt within.

Post by neufer » Wed Nov 14, 2018 10:48 pm

Ann wrote:
Wed Nov 14, 2018 7:20 pm

Long ago, a colleague of mine claimed to have been told, during her visit to Spain, that the wine in one of the vats in one Spanish village turned out to be particularly delicious. Later, during the cleaning of the vats, the body of a missing vineyard worker was found in the vat that had produced the superior wine. Nowadays, may colleague said, vineyard workers are not sacrificed in order to make splendid wine, but instead a large ham is placed in each of the vats, to give the maturing wine the "body" it needs!
http://monk.wikia.com/wiki/Mr._Monk_Gets_Drunk wrote:
Click to play embedded YouTube video.
<<While it takes Adrian Monk a few tries to get it right, he summarizes the case: after a few hands of poker, Ben Gruber went back to his room for more cash, when he suddenly suffered a fatal heart attack. The other guests, along with the hotel owner and one of the waiters, came up to check on him, and found him dead, with a suitcase full of money open beside him. The guests knew that this was the kind of money someone might come looking for, so they decided to divide the money among themselves, and then act as though Gruber had never been there. This meant hiding the body, junking Gruber's vehicle, removing his name from the guest register, re-shooting the group photo without him, and collectively denying that he had been there. One of the guests, a psychiatrist, points out that the police have found neither the body nor the money, and so the more likely explanation is that Gruber escaped the hotel in the middle of the night with the money. The police start to let the guests depart, then Natalie notices a strange taste in the new house wine she has been drinking, which Stottlemeyer recognizes as Aqua Velva aftershave (much to Natalie's horror). Armed with that clue, the police find Gruber's body floating in a wine vat next door.>>
Art Neuendorffer