Starship Asterisk*

robgendler wrote:Luminance in this regard refers to "detail". The luminance or luminosity portion of an image provides the detail. The luminance can be an unfiltered set of exposures which is a common method among amateur astrophotographers however any narrowband or wideband (or combination thereof) set of data can be used as luminance in an image to provide detail. In this case I combined mostly 6565nm h-alpha data sets from the Subaru to provide luminance (detail) against Martin's mapped color image. In addition I layered Hubble data (narrowband SII, OIII, Ha) onto the image. I hope this clarifies the method I used to combine the data sources.

ThePiper wrote:

Chris Peterson wrote:No more dust, since the stellar wind blows it all away, creating a dust-free bubble around stars even in the middle of dust-rich nebulas.

Yes, as we can see. But what's the mechanism of "blowing away" by stellar wind? Is the kinetic energy of single electrons and protons sufficient to accelerate and push entire dust molecules, particles and even clumps? The mass-relation could easy be 1: x times 1E9!

Chris Peterson wrote:No more dust, since the stellar wind blows it all away, creating a dust-free bubble around stars even in the middle of dust-rich nebulas.

Ann wrote:

Anthony Barreiro wrote:
So in the Trifid image, would we presume that there is a star (or a binary star? or cluster of stars?) in the "head" and that the "antennae" are jets from the star(s)?

Yes, I believe that that is exactly what we are seeing, although I wouldn't try to guess how many stars we actually see forming here. The most obvious "antenna" is almost certainly created by a star in the process of forming. But there are other jets here too. The other conspicuous ones may also very well be created by forming stars, but there are other, fainter and broader jets that may have other origins.

Ann

stephen63 wrote:In this case, I believe, the main component of the image are three narrow band channels(Ha/OIII/SII) from Hubble. The color data from Mr Pugh is used for the star color. I'm just guessing but its what I would do. The Luminance is indeed taken through a luminance filter. It also has a bandpass, its not just a clear piece of glass. It rejects the infra red and near infra red frequencies but passes the visible spectrum, which adds detail to the object as well as luminosity. I can't recall seeing a luminance filter ever being used by the Hubble.

DavidLeodis wrote:What confused me about luminance in regard to the APOD is that the information brought up through the link is that luminance (putting it simply) is the brightness of an object, yet in the explanation it stated the "image is a composite with luminance taken from an image by the 8.2-m ground-based Subaru Telescope..." which does not seem to be using luminance as the brightness but rather as a filter.

stephen63 wrote:

DavidLeodis wrote:Thanks for that link bystander, which is appreciated. My understanding, on reading through its information, is that the information brought up through the "luminance" link in the explanation is confusing as it does not seem to be giving the same meaning of luminance that luminance does in image data.

David. The advantage of using the luminance filter/data/channel is it's relatively high signal to noise ratio(SNR). The human eye perceives detail in the luminance image. Higher SNR means we can stretch the data more without the noise becoming objectionable. Your eyes don't detect noise as easily in the color channels, so a lower SNR is acceptable. If it does get excessively noisy, just back off of the stretch, reduce the saturation, or run a noise eduction action. I'm sure there are a lot of other ways to skin a cat, but that's the gist of it. Also, when adding the luminance on top of the RGB data, it doesn't get its own channel. There are only three, as far as I know! Hope this helps!

Anthony Barreiro wrote:
So in the Trifid image, would we presume that there is a star (or a binary star? or cluster of stars?) in the "head" and that the "antennae" are jets from the star(s)?

DavidLeodis wrote:Thanks for that link bystander, which is appreciated. My understanding, on reading through its information, is that the information brought up through the "luminance" link in the explanation is confusing as it does not seem to be giving the same meaning of luminance that luminance does in image data.

bystander wrote:Color CCD Imaging with Luminance Layering by Robert Gendler

Ann wrote:

Click to view full size image

The way I understand it, jets form at right angles to an accretion disk. Young stars accrete mass through accretion disks. This Hubble image of a portion of the Carina Nebula shows two "pillars of creation", which both have jets at their "tops". I'd say that a young star is forming at the very top of these two pillars. You can see that the topmost one has two distinct jets, one in either direction. The jet on the left appears to encounter a strong stellar wind, probably from one of the hot stars in the region, and there is a bow shock at the tip of this jet.

I believe there are similarities between the jets that accompany star formation and the jets that emanate from the centers of active galaxies, although these are phenomena on vastly different scales.

Ann

Anthony Barreiro wrote:This is a beautiful and fascinating image, thanks to everyone who contributed and to Dr. Gendler for putting it all together.

For me, the experience of observing the Trifid many times through smaller and larger telescopes and teasing out as much detail as I can see makes this image much more interesting and compelling than an image of something I've never observed directly. I know where those dust lanes and bright patches are, and I can match up this gloriously detailed and colored image with my mental map of the Trifid.

Those two antennae in the bottom of the picture are reminiscent of the "Pillars of Creation" in the iconic Hubble image of the Eagle nebula. I assume that each antenna contains a young protostar (or perhaps each antenna holds a pair of protostars?) forming out of a clump of gas and dust, while the radiation from big hot stars above them in the picture is simultaneously blowing the gas and dust away, leaving a trail of gas and dust behind the young stars. Does this make sense?

Beyond wrote:

bystander wrote:

Kelly in Space wrote:There's a mound at the bottom of the image with 2 projections that look like Star Trek character Andorian antennae.

[url=http://hubblesite.org/newscenter/archive/releases/1999/42/image/a/][b][i]The Trifid Nebula: Stellar Sibling Rivalry[/i][/b][/url] [b][i]Credit: NASA and Jeff Hester (Arizona State University)[/i][/b]

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That is rather amazing... but we can tell it's not Andorian, as it's not blue. If it was blue... Ann would have commented on it already.