APOD: The Beautiful Trifid (2013 Jul 25)

[APOD Robot]

The 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 illustrates three different types of astronomical nebulae; red emission nebulae dominated by light emitted by hydrogen atoms, blue reflection nebulae produced by dust reflecting starlight, and dark nebulae where dense dust clouds appear in silhouette. The bright red emission region, roughly separated into three parts by obscuring dust lanes, lends the Trifid its popular name. But in this sharp, colorful scene, the red emission is also surrounded by the the telltale blue haze of reflection nebulae. Pillars and jets sculpted by newborn stars, below and left of the emission nebula's center, appear in Hubble Space Telescope close-up images of the region. The Trifid Nebula is about 40 light-years across.

<< Previous APOD

This Day in APOD

Next APOD >>

[/b]

[Ann]

The Trifid is a glorious nebula which looks great in almost all RGB images. Today's picture is certainly splendid.

The Trifid nebula can actually be compared with the Orion Nebula in that it has its own "Trapezium cluster". The Trifid, like the Orion Nebula, is powered by a small, tight group of central stars. As is the case in the Orion Nebula, one star alone is so hot and bright that it does most of the ionizing of the nebula all of its own. The Theta-1 C Orionis of the Trifid Nebula is called HD 164492.

The Trifid consists of a red emission nebula surrounded by a blue reflection nebula. This seems unusual, but the unusual thing about the Trifid is probably just that its surrounding reflection nebula is so bright and obvious.

Click to view full size image

Photo: Neil Fleming

The Cocoon nebula is interestingly similar to the Trifid Nebula, even though it is almost certainly smaller and less powerful. But like the Trifid, it is powered by one star alone, and like the Trifid, it consists of a red emission nebula surrounded by a blue reflection nebula.

Click to view full size image

Photo: R. Jay GaBany

I have been wondering about the yellow star which appears to be a contributing source to the blue reflection nebula of the Trifid. The star is an F-type star, HD 164514, but that is about all I know about it, since it never had its parallax measured by the Hipparcos satellite. In many pictures it looks "untouched" by the reflection nebula surrounding it, as if it was a foreground object. But in R. Jay Gabany's picture to the right, it appears to add its yellowish light to a patch of the red emission nebula. The same effect can be seen, although faintly, in today's APOD.

Ann

[rstevenson]

The link "this sharp, colorful scene" gives a 404 error.

Rob

[owlice]

Thanks, Rob; should be this: http://www.astromodelismo.es/Web%20Astr ... /index.htm

[neufer]

[b][color=#0000FF][size=135]Otto was typing too fast and typed '%20Fotos' for 'Fotos'[/size][/color][/b]

---

The link "this sharp, colorful scene" gives a 404 error.

Works fine on the APOD:

http://www.astromodelismo.es/Web%20Astr ... /index.htm

[owlice]

Well, now it does!

[A Regular Viewer]

How many times are you going to post the same picture of the Trifid Nebula?

[Chris Peterson]

How many times are you going to post the same picture of the Trifid Nebula?

Since this is the first time it's been posted, we'll have to wait a few years to answer your question.

[neufer]

Well, now it does!

Then you might correct Otto's typo as well.

[stephen63]

Well, now it does!

Then you might correct Otto's typo as well.

Since Otto appears to be a backup, lets hope the primary doesn't fail.

[Chris Peterson]

Then you might correct Otto's typo as well.

Come on... that's my favorite kind of typo. I think of it as a careful reading challenge!

[wbill]

I was wondering about the size of the nebula in relation to the stars around it. Is there one star at the heart of the nebula? which one is it? How many time larger that the circumference of the star is the circumference of the nebula?

[neufer]

The 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 illustrates three different types of astronomical nebulae; red emission nebulae dominated by light emitted by hydrogen atoms, blue reflection nebulae produced by dust reflecting starlight, and dark nebulae where dense dust clouds appear in silhouette. The bright red emission region, roughly separated into three parts by obscuring dust lanes, lends the Trifid its popular name. But in this sharp, colorful scene, the red emission is also surrounded by the the telltale blue haze of reflection nebulae. Pillars and jets sculpted by newborn stars, below and left of the emission nebula's center, appear in Hubble Space Telescope close-up images of the region. The Trifid Nebula is about 40 light-years across.

[tkc]

I'm under the impression, maybe a false one, that all matter higher than helium has to be created in a star. So, a question about all this dust: is it all molecular debris from previously exploded/dead stars?

[Chris Peterson]

I'm under the impression, maybe a false one, that all matter higher than helium has to be created in a star. So, a question about all this dust: is it all molecular debris from previously exploded/dead stars?

There is a trace of primordial lithium, as well. But you are correct. Outside of hydrogen and most helium, all that stuff we see in these nebulas was produced by stellar nucleosynthesis and by supernova nucleosynthesis. Although the dust is very apparent visually, it represents only a small fraction of the total mass of the nebula, most of which is hydrogen and helium gas, along with smaller amounts of oxygen and nitrogen.

[neufer]

I'm under the impression, maybe a false one, that all matter higher than helium has to be created in a star. So, a question about all this dust: is it all molecular debris from previously exploded/dead stars?

There is a trace of primordial lithium, as well. But you are correct. Outside of hydrogen and most helium, all that stuff we see in these nebulas was produced by stellar nucleosynthesis and by supernova nucleosynthesis.

• Or, perhaps, colliding neutron stars.

[Boomer12k]

What a gloriously, beautiful picture! Just AWESOME.

The shapes in the bottom of the Emission nebula are very reminiscent of the Eagle Nebula. Strange animals and lifting pillars. While at the top leftish a Horned Demon wraps himself around the reddish globe of the Triffid...


:---[===] *

[Beyond]

Or, perhaps, colliding neutron stars.

I wonder how long it would take for the radiation of 'freshly' made gold to disperse, so it would be 'safe' for humans to handle?

[neufer]

Or, perhaps, colliding neutron stars.

I wonder how long it would take for the radiation of 'freshly' made gold to disperse, so it would be 'safe' for humans to handle?

A few years perhaps.

<<Gold (Au) has one stable isotope, ¹⁹⁷Au, and 36 radioisotopes with ¹⁹⁵Au being the most stable with a half-life of 186 days. A jacket of natural ¹⁹⁷Au, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope ¹⁹⁸Au with a half-life of 2.697 days and produce approximately .411 MeV of gamma radiation, significantly increasing the radioactivity of the weapon's fallout for several days. Such a weapon is not known to have ever been built, tested, or used.>>

[Chris Peterson]

I wonder how long it would take for the radiation of 'freshly' made gold to disperse, so it would be 'safe' for humans to handle?

Ordinary gold wouldn't be radioactive at all. There are a number of radioisotopes of gold, most of which have half-lives of a few seconds or less, and the longest of which is only 186 days. So you wouldn't need to worry about radioactive gold. Of course, it might be accompanied by other heavy elements that could be radioactive.