APOD: A Beautiful Trifid (2017 Oct 20)

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APOD: A Beautiful Trifid (2017 Oct 20)

Post by APOD Robot » Fri Oct 20, 2017 4:10 am

[img]https://apod.nasa.gov/apod/calendar/S_171020.jpg[/img] A Beautiful Trifid

Explanation: The beautiful Trifid Nebula is a cosmic study in contrasts. Also known as M20, it lies about 5,000 light-years away toward the nebula rich constellation Sagittarius. A star forming region in the plane of our galaxy, the Trifid does illustrate three different types of astronomical nebulae; red emission nebulae dominated by light from hydrogen atoms, blue reflection nebulae produced by dust reflecting starlight, and dark nebulae where dense dust clouds appear in silhouette. But the red emission region roughly separated into three parts by obscuring dust lanes is what lends the Trifid its popular name. Pillars and jets sculpted by newborn stars, below and left of the emission nebula's center, appear in famous Hubble Space Telescope close-up images of the region. The Trifid Nebula is about 40 light-years across. Just too faint to be seen by the unaided eye, it almost covers the area of the Moon in planet Earth's sky.

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by Boomer12k » Fri Oct 20, 2017 7:32 am

Boy! That is one pretty picture...

My Close Up...
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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by Ann » Fri Oct 20, 2017 8:15 am

Today's APOD is very beautiful.

I've wondered for a long time if that bright yellow star sitting in the middle of the blue reflection nebulosity might have anything to do with that extended blue light. The star, HD 164514, is an F5-type star, and it appears to be distant, which suggests it is intrinsically bright. If it is indeed distant, so that it is a bright F5-type star, it will emit a lot of blue light. The star appears to be reddened, which would be the case if a lot of its blue light had been scattered by dust.

But the blue reflection nebula doesn't appear to be particularly bright in the immediate vicinity of the star, so I don't know if the star and the reflection nebula are connected. The question is, if the star and the reflection nebula are not connected, what would be the cause of that large reflection nebula?

In his book A View of the Universe, David Malin could show a faint blue rim of reflection nebulosity around the otherwise very red Lagoon Nebula. The same effect can be seen in this 1.7 MB picture of the Lagoon and the Trifid by Éder Iván. It's a beautiful picture, but you should look at it at your own risk.

But the blue rim around the Lagoon is very faint and narrow, while the blue reflection nebula north of the red Trifid Nebula is relatively bright and very extended. These two reflection nebulas can't be caused by the same mechanism.

I like your picture, Boomer! :D

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by BDanielMayfield » Fri Oct 20, 2017 1:00 pm

Ann wrote:I've wondered for a long time if that bright yellow star sitting in the middle of the blue reflection nebulosity might have anything to do with that extended blue light. The star, HD 164514, is an F5-type star, and it appears to be distant, which suggests it is intrinsically bright. If it is indeed distant, so that it is a bright F5-type star, it will emit a lot of blue light. The star appears to be reddened, which would be the case if a lot of its blue light had been scattered by dust.

But the blue reflection nebula doesn't appear to be particularly bright in the immediate vicinity of the star, so I don't know if the star and the reflection nebula are connected. The question is, if the star and the reflection nebula are not connected, what would be the cause of that large reflection nebula?
It looks to me that HD 164514 would have to be the illuminator of the blue reflection nebula, unless there is another bright star hidden behind the red part of the Trifid. The lack of brightness near the star would be a natural effect of its stellar winds clearing out that area.

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by bls0326 » Fri Oct 20, 2017 1:20 pm

The "5,000 light-years" link in today's Explanation leads to an interesting Atlas of the Universe website. The website shows it was last updated in 2006, still interesting though.

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by neufer » Fri Oct 20, 2017 2:20 pm

http://hubblesite.org/image/915/news_release/1999-42 wrote:

The Trifid Nebula: Stellar Nursery Torn Apart By Radiation From Nearby Star

<<This NASA Hubble Space Telescope image of the Trifid Nebula reveals a stellar nursery being torn apart by radiation from [HD 164492A, an O7.5III star with a mass more than 20 times the mass of the Sun]. The picture also provides a peek at embryonic stars forming within an ill-fated cloud of dust and gas, which is destined to be eaten away by the glare from the massive neighbor. This stellar activity is a beautiful example of how the life cycles of stars like our Sun is intimately connected with their more powerful siblings. The Hubble image shows a small part of a dense cloud of dust and gas, a stellar nursery full of embryonic stars. This cloud is about 8 light-years away from the nebula's central star, which is beyond the top of this picture. A stellar jet [the thin, wispy object pointing to the upper left] protrudes from the head of a dense cloud and extends three-quarters of a light-year into the nebula. The jet's source is a very young stellar object that lies buried within the cloud. Jets such as this are the exhaust gases of star formation. Radiation from the massive star at the center of the nebula is making the gas in the jet glow, just as it causes the rest of the nebula to glow. The jet in the Trifid is a "ticker tape," telling the history of one particular young stellar object that is continuing to grow as its gravity draws in gas from its surroundings. But this particular ticker tape will not run for much longer. Within the next 10,000 years the glare from the central, massive star will continue to erode the nebula, overrunning the forming star, and bringing its growth to an abrupt and possibly premature end. Another nearby star may have already faced this fate. The Hubble picture shows a "stalk" [the finger-like object] pointing from the head of the dense cloud directly toward the star that powers the Trifid. This stalk is a prominent example of the evaporating gaseous globules, or "EGGs," that were seen previously in the Eagle Nebula, another star-forming region photographed by Hubble. The stalk has survived because at its tip there is a knot of gas that is dense enough to resist being eaten away by the powerful radiation. Reflected starlight at the tip of the EGG may be due to light from the Trifid's central star, or from a young stellar object buried within the EGG. Similarly, a tiny spike of emission pointing outward from the EGG looks like a small stellar jet. Hubble astronomers are tentatively interpreting this jet as the last gasp from a star that was cut off from its supply lines 100,000 years ago. The images were taken Sept. 8, 1997 through filters that isolate emission from hydrogen atoms, ionized sulfur atoms, and doubly ionized oxygen atoms. The images were combined in a single color composite picture. While the resulting picture is not true color, it is suggestive of what a human eye might see.>>
Art Neuendorffer

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by Fwipt » Fri Oct 20, 2017 4:53 pm

SHH! Don't let the trifids hear you.

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by Ann » Fri Oct 20, 2017 5:06 pm

neufer wrote:
http://hubblesite.org/image/915/news_release/1999-42 wrote:

The Trifid Nebula: Stellar Nursery Torn Apart By Radiation From Nearby Star

<<This NASA Hubble Space Telescope image of the Trifid Nebula reveals a stellar nursery being torn apart by radiation from [HD 164492A, an O7.5III star with a mass more than 20 times the mass of the Sun]. The picture also provides a peek at embryonic stars forming within an ill-fated cloud of dust and gas, which is destined to be eaten away by the glare from the massive neighbor. This stellar activity is a beautiful example of how the life cycles of stars like our Sun is intimately connected with their more powerful siblings. The Hubble image shows a small part of a dense cloud of dust and gas, a stellar nursery full of embryonic stars. This cloud is about 8 light-years away from the nebula's central star, which is beyond the top of this picture. A stellar jet [the thin, wispy object pointing to the upper left] protrudes from the head of a dense cloud and extends three-quarters of a light-year into the nebula. The jet's source is a very young stellar object that lies buried within the cloud. Jets such as this are the exhaust gases of star formation. Radiation from the massive star at the center of the nebula is making the gas in the jet glow, just as it causes the rest of the nebula to glow. The jet in the Trifid is a "ticker tape," telling the history of one particular young stellar object that is continuing to grow as its gravity draws in gas from its surroundings. But this particular ticker tape will not run for much longer. Within the next 10,000 years the glare from the central, massive star will continue to erode the nebula, overrunning the forming star, and bringing its growth to an abrupt and possibly premature end. Another nearby star may have already faced this fate. The Hubble picture shows a "stalk" [the finger-like object] pointing from the head of the dense cloud directly toward the star that powers the Trifid. This stalk is a prominent example of the evaporating gaseous globules, or "EGGs," that were seen previously in the Eagle Nebula, another star-forming region photographed by Hubble. The stalk has survived because at its tip there is a knot of gas that is dense enough to resist being eaten away by the powerful radiation. Reflected starlight at the tip of the EGG may be due to light from the Trifid's central star, or from a young stellar object buried within the EGG. Similarly, a tiny spike of emission pointing outward from the EGG looks like a small stellar jet. Hubble astronomers are tentatively interpreting this jet as the last gasp from a star that was cut off from its supply lines 100,000 years ago. The images were taken Sept. 8, 1997 through filters that isolate emission from hydrogen atoms, ionized sulfur atoms, and doubly ionized oxygen atoms. The images were combined in a single color composite picture. While the resulting picture is not true color, it is suggestive of what a human eye might see.>>
The human eye would see pink stars?

What has the owner of that eye been smoking?

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by neufer » Fri Oct 20, 2017 6:08 pm

Ann wrote:
The human eye would see pink stars? What has the owner of that eye been smoking?
https://en.wikipedia.org/wiki/Seeing_pink_elephants wrote:
<<"Seeing pink elephants" is a euphemism for drunken hallucination caused by alcoholic hallucinosis or delirium tremens. The term dates back to at least the early 20th century, emerging from earlier idioms about snakes and other creatures.

In 1896, in what may be the earliest recorded example of a (partially) pink elephant, one of Henry Wallace Phillips' "Fables of our Times" referred to a drunken man seeing a "pink and green elephant and the feathered hippopotamus." In 1897, a humorous notice about a play entitled "The Blue Monkey," noted that, "We have seen it. Also the pink elephant with the orange trunk and the yellow giraffe with green trimmings. Also other things."

An early literary use of the term is by Jack London in 1913, who describes one kind of alcoholic, in the autobiographical John Barleycorn, as "the man whom we all know, stupid, unimaginative, whose brain is bitten numbly by numb maggots; who walks generously with wide-spread, tentative legs, falls frequently in the gutter, and who sees, in the extremity of his ecstasy, blue mice and pink elephants. He is the type that gives rise to the jokes in the funny papers."

A well-known reference to pink elephants occurs in the 1941 Disney animated film Dumbo. Having taken a drink of water from a bucket spiked with champagne, Dumbo begins to hallucinate singing and dancing elephants in a segment known as "Pink Elephants on Parade".>>
http://little-piney-observatory.blogspot.com/2015/09/creating-hubble-palette-images.html wrote:
Creating Hubble Palette Images
Little Piney Observatory. Tuesday, September 22, 2015

<<Hubble palette images are basically created by using data from three narrowband filters, SII (sulfur) is assigned to the red channel, Ha (hydrogen alpha) to the green, and OIII (oxygen) to the blue. Some people also call this SHO, substituting the SII (S), Ha (H), and OIII (O) in the channels represented as RGB, or red, green, and blue. Just simply putting the image together in this fashion will usually result in an image that is very green, since Ha is almost always very dominant in every image. The process I use to create the image is sometimes referred to as modified hubble palette, because it uses some selective color adjustments to manipulate the colors. However, this "modified" hubble palette is what creates what most are so used to seeing in the hubble images with the classic golds and blues. If you do a search of hubble palette you will likely see a lot of these images that have pink/magenta colored stars. The pink stars always gave me fits.>>
Art Neuendorffer

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by Chris Peterson » Fri Oct 20, 2017 6:15 pm

neufer wrote:
Ann wrote: The human eye would see pink stars? What has the owner of that eye been smoking?
https://en.wikipedia.org/wiki/Seeing_pink_elephants wrote: <<"Seeing pink elephants" is a euphemism for drunken hallucination caused by alcoholic hallucinosis or delirium tremens.
I see them a lot, without so much as a beer in me.
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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by Ann » Fri Oct 20, 2017 8:46 pm

Delphinium grandiflorum 'Butterfly Blue'.
Funny, Chris. Are they pink delphiniums? What a waste. Other varieties of delphiniums come in such utterly delightful shades of blue.

On a slightly more serious note, I just checked out Patrick Gillilands portrait of the Iris Nebula, and I really think there are similarities between the Iris Nebula and the reflection nebula part of the Trifid Nebula.

In both cases, the reflection nebula is centered on one bright star, whose stellar wind has cleared out a rectangular-looking "hole" in the surrounding dust. Both central stars are reddened by dust, but HD 200775, the central star of the Iris Nebula, is a much hotter star than HD 164514, and it has injected a lot more energy into its surrounding dusty nebula than its F5-type Trifid Nebula equivalent. That would explain why the structures of the Iris Nebula are so much "sharper" than the structures of the blue part of the Trifid Nebula.

So yes, Bruce, I think you are right that HD 164514 is the star that lights up the reflection nebula part of the Trifid.

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by Chris Peterson » Fri Oct 20, 2017 9:09 pm

Ann wrote:Funny, Chris. Are they pink delphiniums? What a waste. Other varieties of delphiniums come in such utterly delightful shades of blue.
No, they're Elephant's Head, Pedicularis groenlandica. We have beautiful delphiniums here, too.
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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by geckzilla » Fri Oct 20, 2017 9:11 pm

Ann wrote:Funny, Chris. Are they pink delphiniums? What a waste. Other varieties of delphiniums come in such utterly delightful shades of blue.
I've always found this sentiment you express so often to be oddly offensive, Ann.
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by neufer » Fri Oct 20, 2017 10:54 pm

geckzilla wrote:
Ann wrote:
Funny, Chris. Are they pink delphiniums? What a waste.
Other varieties of delphiniums come in such utterly delightful shades of blue.
I've always found this sentiment you express so often to be oddly offensive, Ann.
Ann is an advocate of "Multimessenger Astronomy" as long as it is restricted to different shades of blue.
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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by heehaw » Fri Oct 20, 2017 11:45 pm

Some people are color bling (excuse me, colour blind), and don't know it.

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by Ann » Sat Oct 21, 2017 4:59 am

geckzilla wrote:
Ann wrote:Funny, Chris. Are they pink delphiniums? What a waste. Other varieties of delphiniums come in such utterly delightful shades of blue.
I've always found this sentiment you express so often to be oddly offensive, Ann.
Sorry. It's meant as a joke. I think of it as a way of poking fun of myself and my utter fascination with blue things.

I'll try to stop doing it.

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by Ann » Sat Oct 21, 2017 5:11 am

Chris Peterson wrote:
Ann wrote:Funny, Chris. Are they pink delphiniums? What a waste. Other varieties of delphiniums come in such utterly delightful shades of blue.
No, they're Elephant's Head, Pedicularis groenlandica. We have beautiful delphiniums here, too.

(6bl)IMG_20170801_153408.jpg
Thanks for educating me, Chris! You're right, your Elephant's Head don't look like delphiniums.

And your delphiniums are beautiful... as are your Elephant Head.

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Re: APOD: A Beautiful Trifid (2017 Oct 20)

Post by neufer » Sat Oct 21, 2017 10:58 am

Ann wrote:
geckzilla wrote:
Ann wrote:
Funny, Chris. Are they pink delphiniums? What a waste.
Other varieties of delphiniums come in such utterly delightful shades of blue.
I've always found this sentiment you express so often to be oddly offensive, Ann.
Sorry. It's meant as a joke. I think of it as a way of poking fun of myself and my utter fascination with blue things.

I'll try to stop doing it.
We probably all knew you were joking ... It's just that the U.S. has gone through a very difficult week in which our leaders have shown themselves to be anything but colorblind [vs-a-vi: 1) the suffering Americans in wasted Puerto Rico and 2) the minority in Congress].

Feel free to discuss your fascination with blue things but try not to do it by denigrating non-blue things (even in jest).
Art Neuendorffer