Pillars in Triffid Nebula (APOD 26 Dec 2007)

Northerner4 · Post by **Northerner4** » Wed Dec 26, 2007 4:07 pm

It is stated that a very bright star to to top right of the image is eroding the pillar.

I would submit that the bright star is in fact behind the large pillar in the near center of the image. The shadow spokes imply the position.

orin stepanek · Post by **orin stepanek** » Wed Dec 26, 2007 4:58 pm

Your link! http://antwrp.gsfc.nasa.gov/apod/ap071226.html
It does indeed seem very bright behind the large pillar

Maybe that is glowing from the star that is lighting it up?
Orin

Qev · Post by **Qev** » Wed Dec 26, 2007 6:02 pm

Well, bear in mind that the glow we see in this image is due to emission from energized gas, and not from reflection or scattering (at least, I believe that's the case), so the 'halo' around the end of the pillar isn't from backlighting.

This image along with this one give you a good idea what's going on, and you can see the star responsible for all the glowing and erosion.

Northerner4 · Post by **Northerner4** » Thu Dec 27, 2007 11:33 am

I will agree that energized gases are responsible for the glow behind the large pillar, but I still think that the energy causing the glow is from a bright star obscured by the column, not one 'off-screen'.

For a source to be 'off-screen' to the top right, then all the constituent objects in the image would tend to show the radiant shadow spikes, similar to the ones from the large column, and they do not.

For an object to be illuminated to the degree shown, light (energetic streams of particles, what ever) would have to be literally pouring on it like a stream of water, and there is vanishingly little evidence that an object 'off-screen' is providing such an outflow of energy.

I guess this is why we each are allowed to believe the scenario which fit our perceptions.

DavidLeodis · Post by **DavidLeodis** » Thu Dec 27, 2007 3:22 pm

I am also confused with the mention in the explanation that the star at the end of the jet is being stripped of its gas by radiation from a tremendously bright star off screen to the upper right. In the information that is brought up when clicking on both of the 'above picture' links in the explanatiion it states "The thin, corkscrew-shaped line of gas pointing to the upper left is a stellar jet. The jet's source is a very young star buried within the cloud. This jet is the exhaust gas of star formation. The finger-like column of gas points directly toward the "hefty" star that powers the Trifid". I would take that to imply that the tremendously bright star is to the left, but I seem to be wrong.

NoelC · Post by **NoelC** » Thu Dec 27, 2007 5:48 pm

I disagree that there's no evidence of an outflow of energy/particles.

The overall shape and color of the nebula, with the central area having been cleared out and the surfaces of all the dust/gas clouds being illuminated from the obvious direction of the central star are all great indicators of exactly such emission. The very fact that it is all glowing red indicates hydrogen gas is being excited by high energy radiation.

I would agree that the TC2 globule shown in the APOD appears to be somewhat in front of the star, but well off to the side (i.e., not blocking it).

Consider these images (note that the nebula shown in the APOD is in the reddish area in visible light images):

Spitzer image in infrared

Rob Gendler's visible light image

One nit I DO have to pick, however, is that there are a pair of stars that appear at the center of the Trifid Nebula. Perhaps one of these is just coincidentally aligned in space?

-Noel

Starship Asterisk*

Pillars in Triffid Nebula (APOD 26 Dec 2007)

Pillars in Triffid Nebula (APOD 26 Dec 2007)

Pillars in Triffid Nebula, Dec 26, 2007