What do we 'know' about galaxies??

[Biggins]

Somethign I have been pondering for a while: What is it that we can direcly observe from a galaxy, Note I mean 'directly' and not based on ANY assumptions. As far as I can tell the list is very small:

- We can see a red/blue shift in the frequency of light from each side of the galaxy (but without knowing the size of the galaxy we cannot know it's rotational velocity).
With assumptions that the average red-shift is an indication of the distance, we can the in-directly calculate it's size and therefore rotational velocity.

Fact 2: We can see the brightness of the galaxy and, if the resolution is good enough, the brightness of groups of stars in the galaxy.
Is this useful? Are there standard candles for galaxies (standard galaxies, not types of stars)

Fact 3: we can see the shape of the galaxy in the spectrum in which we are detecting (i.e. visible light, radio, infra-red, etc).
Makes a nice picture but does not 'directly' tell us anything other than interactions between clusters/galaxies.


Have I missed something??

[Biggins]

Probably should have been put in a different forum -

[nick c]

hi Biggins,
Seems to me that you are now in the correct forum.
Electric Universe forum description:

Plasma and electricity in space. Failure of gravity-only cosmology. Exposing the myths of dark matter, dark energy, black holes, neutron stars, and other mathematical constructs. The electric model of stars. Predictions and confirmations of the electric comet.

This comes under the heading of "Failure of gravity-only cosmology." The gravity only assumption has resulted in misconceptions of the size and distances of our galactic neighbors and beyond. If the revisions of the Electric Universe and plasma cosmology are correct, our "map" of the visible universe will have to be radically revised. What percentage of a spectrum shift can be attributed to movement and what is intrinsic? If Arp is correct, the redshift as a doppler effect will have to be revisited and we will find that objects that were thought to be bright, large, and faraway are actually dim, small, and nearby. It is a matter of perspective, both literally and figuratively! It seems that much of the "precision" of mainstream yardsticks is illusionary. I suspect that once this new paradigm is accepted, by mainstream, that revisions in the old yardsticks (as well as new yardsticks) will be developed.
Until then we are left with ballpark estimates. For example, a galaxy that cannot be resolved into component stars, is most likely larger and farther away then a galaxy of the same apparent size whose stars can be resolved.

http://www.electric-cosmos.org/galaxies.htm
http://www.holoscience.com/synopsis.php?page=5
http://www.holoscience.com/synopsis.php?page=4
http://www.skepticalinvestigations.org/ ... letter.htm

Nick

[Aardwolf]

Your first fact assumes red shift is a measure of velocity.

[Siggy_G]

Until then we are left with ballpark estimates. For example, a galaxy that cannot be resolved into component stars, is most likely larger and farther away then a galaxy of the same apparent size whose stars can be resolved.

Agree about the ballpark estimates. But regarding galaxies that can't be resolved into component stars, I'm more convinced that they are smaller clouds of plasma (or any size for that matter). Consequentially the rotation of this (measured with redshift...) obviously appears too fast for its size - because it's way smaller than assumed. How does anyone distinguish between a plasma cloud (assumed exploded star / early phase star) and a galaxy, if stars aren't visually resolved within it? And if "stars" can be resolved, how does anyone know for sure they aren't looking at dusty plasma with radiant grains?

I should also add that, from looking at certain images of galaxies, it seems rather tricky to know whether one are looking at a galaxy consisting of stars or a transparent cloud with a star field in front / behind. I mostly just see a plasmoid with transparent surrounding filaments. The stars are in the front / background.

http://www.freewebs.com/bnip1/Astronomy ... %20342.jpg
http://www.extinctionshift.com/sombrero_galaxy_big.jpg (does this galaxy consist of stars?)
http://www.spacetelescope.org/images/sc ... c0710a.jpg

[Biggins]

Again, coming back to my initial point, what are the 'facts' that we know.

Other than a redshift/blueshift, brightness and shape, there is nothing we can say for certain about any galaxy. The only other information must be extracted from this information (with a greater or lesser degre of accuracy).

Am I missing any directly observable 'facts'? I suppose I could add spectral lines, but I think that this must be based on the assumption that the intervening space has no effect on the spectroscopic characteristics of the galaxy.

[jjohnson]

Actually spectroscopic information is crucial to understanding whatever one can from available information about stars. It is not limited to seeing a spectrum of the star; it is inferring which elements are present, either a bright lines because that element is radiating at that frequency/'color', or as dark lines because elements or molecules, present somewhere between the radiating surface of the star and the observer, are absorbing the light at that particular frequency. Fraunhofer started this ball rolling.

Astronomers have ways of estimated the optical corrections for various lengths of the visual column (the "tube" of more or less "open" space between our eye and where the star was when it emitted the light). They correct their spectra to account for this daily. The intervening space can have a significant effect (neglecting distance-dimming) on our imaging of a star or a galaxy, ranging from almost none, to being opaque at some or all usable wavelengths.

What else can a spectrum provide? If there is relative motion between the radiator and the observer, Doppler shift gives one an estimate of the relative velocity - that is, the velocity component parallel to the line of sight between the radiator and the observer. Typically we observe red shifts because, according to the Gravity Universe, most galaxies are moving away from us, as well as the idea that has arisen that the entire universe - space itself - is expanding, and so everything should be getting farther away from everything else and thus should show the combined effects of motion and spatial expansion. Doppler came up with motion-related red shift (or blue shift if the relative motion is toward rather than away).

It was Arp, I think, who raised the issue of "intrinsic red shift" which some bodies have, particularly quasars and ejected masses from quasars. It is related to the age of the ejecta in some way that I do not understand, and it has been observed that this red shift changes relative to the surrounding matter as time goes by, and the red shift decreases as distance from the ejector increases.

Intense magnetic fields, if present, can also affect the Fraunhofer lines in predictable ways, so we have an indicator of the presence or absence of a strong magnetic field thereby.

I looked at one of the APODs of the hubble deep field fairly recently, and noticed that some of the galaxies were red and some were blue and white. I wrote the astronomer author and asked about that - if all these are deep field images, and we are actually looking at such a distance or deep time that we are seeing UV light that has such a great red shift ("z" in the jargon) that its wavelength has shifted down to the near IR, why are some of them blue? Is this false color imagery? The short answer he gave was, yes, it is false color; ALL the stars are red in the original. My guess was that it "looks better" that way.

If stars cannot be resolved as distinct pinpoints, assuming that you have "perfect" optics for the wavelength, then you get into the issue of what is the meaning of resolution. A perfect star image is not a single tiny point of light but instead is a central point of bright light with several less bright surrounding rings - diffraction rings due to the present of optical elements in the path - this is called the Airy disk. Aberrations such as coma or spherical aberration change the appearance of this disc, stretching out the image or turning it into a comet-like shape. If two stars are very close together, their Airy rings overlap and merge somewhat, and their central "peaks" of brightness move closer together. If they are closer together than the eye can resolve, or perceive that there are two bright spots rather than one, then you cannot know with your eye (or instrument if that is the case) that there are two stars hiding in the image. Both Rayleigh and Dawes developed criteria for the angular separation in arc seconds for visual separation, both being influenced adversely when the stars are not "white" and equal in intensity.

Another reason for not seeing stars is distance-induced decrease in brightness - from the absolute magnitude or brightness of a star, light, like gravity, decreases as it moves away from its source, and becomes less bright. If it hasn't enough energy to excite your eyes' receptors by the time it gets here, we can't see it. This is why telescopes are so valuable - they gather light across a large cross section, or aperture, and bring it together at the focus so that the overall intensity from the wide butterfly net is great enough to excite your eye or the camera and create an image. What appears as a blur in one telescope may be a galactic field full of pinpoint stars. If you have a whole lot of stars surrounding the center of a galaxy, and you see only a blur of light, it is likely that their peak intensity is insufficient to tell your eye, "a star is right here" but across the field of incoming light your eye picks up enough photons to realize that light is coming from that patch of sky.

At great distances so many stars are so close to one another in terms of their angular difference in your field of vision that the eye has insufficient resolving power to differentiate among them. We get great images of Andromeda nearby (relatively speaking) with large telescopes and high-pixel-count astro-imaging cameras, but look at it on a dark night with binoculars, and you are lucky to see more than the large central blur and maybe a star-like image of its small companion galaxy. Look at the thousands of galaxies in the Hubble deep field and no stars are visible. just galaxy shapes with blurry edges.

Do we know distances to galaxies with great precision? No; probably with a lot less precision than astronomers want us to believe, and the precision falls off with increasing distance. Smart people have thought up a lot of interesting and plausible methods of obtaining galactic distances, since parallax doesn't work outside the Milky Way, but there is evidence that the star types used as "standard candles" may exhibit too much variability to be all that standardized. After Arp, red shift is also a suspect method of relating to distance, as well as to age. We are running out of options and the astrophysical world is full of educated guesses. Very well-educated and well-meaning guesses, but estimates all the same.

It is interesting that Doppler shifts are precise enough to show that galaxies have a relatively "flat" or constant rotational curve, qualitatively different from a planetary system and more like a rigid disk, once you move a relatively short distance away from the area near the center. Doppler imaging, at least within our galaxy, is so precise that tiny wobbles of a star due to a nearby planet (or binary companion) can be used to infer the presence of the second body, or more, visible in the stare's glare or not. Astronomical technology is astoundingly good in many respects. The Electric Universe has some bones to pick and ideas to add in achieving a better idea of how the universe functions, but we get really good data to work with today, within our own galaxy. We have to extrapolate some of what we learn about our own galaxy at least to similar galaxies - the laws of physics are likely the same everywhere, despite the arguments over whether they are or not (angels on a pin). Big spiral galaxies here and there probably behave similar to our own. Why should ours be the only soldier out of step, in other words. Globulars are probably all formed pretty much the same way for similar physical reasons. Dwarf stars probably form wherever conditions are just right for dwarf stars to be formed, whether it's here or out in the deep field somewhere.

We actually know a lot of valid or useful information about other galaxies and their stars. Some of the conclusions which modern astronomers and cosmologists draw from them is where I step back and try to take a closer look, in light of what I have learned at the hands of EU proponents.

[Siggy_G]

Excellent summary of the methods used for detecting / analyzing galaxies and stars. Agreeing with most of what you say. Some comments though:

Intense magnetic fields, if present, can also affect the Fraunhofer lines in predictable ways, so we have an indicator of the presence or absence of a strong magnetic field thereby.

In what way and to which degree does magnetic fields affect absorption spectra? I tried to find info about it on the net. From what I gather it affects the matter which the light passes through, but not the light itself. If anyone knows more about magnetic fields' effect on electromagnetic waves, I'd be interested to know (because it's relevant for how spectral data is interpreted).

(...) Is this false color imagery? The short answer he gave was, yes, it is false color; ALL the stars are red in the original. My guess was that it "looks better" that way.

A lot of astronomical images are composite and visually guesstimated. In my opinion, turning desaturated images into randomly disco-light colored star fields is rather misleading. Same goes for multi-colored nebulae.

If stars cannot be resolved as distinct pinpoints, assuming that you have "perfect" optics for the wavelength, then you get into the issue of what is the meaning of resolution.

Fair enough, but regarding galaxy images where one can't tell whether there exist star pixels within the galaxy, it seems to me that they are just like clusters of plasma, like structured nebulae.

Another reason for not seeing stars is distance-induced decrease in brightness - from the absolute magnitude or brightness of a star, light, like gravity, decreases as it moves away from its source, and becomes less bright. If it hasn't enough energy to excite your eyes' receptors by the time it gets here, we can't see it.

This says a lot about Olber's paradox (http://en.wikipedia.org/wiki/Olbers%27_paradox). There simply no reason why photons from all stars out there should reach our sight at any given point and turn the night sky over bright.

Doppler imaging, at least within our galaxy, is so precise that tiny wobbles of a star due to a nearby planet (or binary companion) can be used to infer the presence of the second body, or more, visible in the stare's glare or not.

It would be interesting to see one of these images, because the best resolution images of stars, which I have seen, aren't really of high resolution per star. How they can tell the anomalies in the shape of a far distant star (appearing like a blurry pixel) makes me raise an eyebrow.

[Siggy_G]

Here's a site with several interesting images of nabulae:

http://rigel.csi.cuny.edu/rowan/lecture ... ebulae.htm

Of course, the text is based on mainstream descriptions, but the images are just reminders that what's out there is filaments upon filaments, and all about the various interactions and dynamics within them. From seeing this, and images of galaxies, it seems obvious that the tiniest dynamics (electricity and magnetic fields) add up to control the largest structures, which again turn into some variation of spiraling angular momentum and clustering of matter. In addition, there are the radiating dynamics which plays its role as well.

[Biggins]

Thanks for that very long reply jjonhson, but just a couple of points...

Spectroscopic information: We can tell the elements contained in a galaxy/star by noting the spectral lines in the spectrum when looking at the object. In order to remove the effects of the intervening space, the spectrum of a nearby 'dark' are can be analysed and the differences removed (i.e. (star+space) spectrum - space spectrum = star spectrum. Obviously the 'space spectrum' is also the spectrum of the matter behind the star/galaxy, but it can be assumed that this has a lesser effect than foreground matter and can be ignored.

Relative motion: This is only valid if the only redshift is due to doppler, i.e. a motion only cause of redshift. If this, as Arp suggests, is not the case then this measure of distance is not valid. In any case, the distance is an interpretation of redshift, not a direcly measureable quantity.




Detection of planets: Actually, this is measured not only by the 'wobble' of the star (only recently have we had the resolution for this and only for relatively close stars), but by the change in brightness of the star (the one most used to detect plantes) and several other methods. In each case, this only works if the star is small or the planet is very big.

[jjohnson]

Regarding Zeeman splitting of Fraunhofer lines in magnetic fields, from one of the science definition sites,

The study of the Fraunhofer spectrum is the principal means of learning about physical conditions in the solar atmosphere. On the resolved solar disk, variations in line strength from point to point convey information about temperature, Doppler shifts of the lines reveal gas motions, and line splitting from the Zeeman effect maps magnetic fields. Because each line represents a chemical element, the composition of the solar atmosphere can be deduced.

I think that, in retrospect, such fine resolution as to create magnetograms based on the Zeeman effect on the Fraunhofer lines can only be conducted on one star - ours. Forget that my implication concerned galaxies. - that's wrong, and thanks for noticing.

Biggins - good points. We just don't have that many accurate yardsticks to work with, do we? The best guess might be "they are similar in stellar density and variety if they look a lot like our galaxy."

I forget to put in the analogy for resolution that I was thinking of: If you have a sheet of black paper and on it is printed a very fine, closely spaced dot field of small white sposts, and stand back some distance so that you can't see individual dots, what you see is a hazy gray field. That is the "glow" seen around, or even identified as, poorly resolved galaxies. Hubble has some amazing upgrades comparing older Palomar B/W photographic plates of galaxies with the latest installation of the Wide Field Optics showing the much better resolved and in color same galaxies.

Good discussion, all.

[Harry Costas]

G'day from the land of ozzzzzz

It's not enough just to know the elements.

We need to know the sub atomic particles such as axions that make up ALL and that involves the most complicated experiments and instruments in detecting.