Elliptical Selection

elliptical dab ratio

The orbit around Sirius is elliptical.

Makes an elliptical or circular selection

So this is still elliptical shapes.

They're the white, fuzzy, elliptical things here.

They're called elliptical for a really good reason.

And here are some velocity profiles of elliptical galaxies.

In elliptical galaxies there is hardly any cold gas.

But actually, ellipticals are not purely elliptical in shape.

One of, disky, elliptical and now we think that in fact most elliptical galaxies those originally classified as elliptical showless kind of isophotes lemon shaped, actually you have disks and there may be close to zeroes than elliptical sproper but there is a continuum of properties there are no sharp distinctions.

So the stars in elliptical galaxies have largely random motions.

Let us now turn to the shapes of elliptical galaxies.

Let us now turn to the internal motions inside elliptical galaxies.

As you would recall, the stars in elliptical galaxies move randomly.

And here is a blatant example of dust in a elliptical galaxies.

The way we quantify structure for elliptical galaxies, is through surface photometry.

We can infer what is the underlying velocity dispersion of the elliptical galaxy.

Well relaxed looking, symmetric round clusters tend to be dominated by elliptical galaxies.

So here are some plots of surface brightness for a thousand elliptical galaxies.

I can't do anything for you unless you stop being so damned elliptical.

The two families with thicker symbols are elliptical galaxies and dwarf ellipticals and dwarf spheroidals.

And now we think that the shapes of elliptical galaxies are due entirely, to this anisotropy.

We now turn our attention to the other end of the Hubble sequence, the elliptical galaxies.

Spectral stars that are like those that make elliptical convolved with say Gaussian distribution of Doppler shifts.

As you go up in radius, what looks in inner part is a box elliptical maze start

This is an elliptical galaxy NGC 1316 which is in the center of the nearby Fornax Cluster.

About a billion miles away, here's what happens to Earth's orbit it becomes elliptical instead of circular.

You can do very similar thing for elliptical galaxies which is essentially same thing we've done for clusters.

So here are some examples from group, an instrument called Sauron of several elliptical galaxies as indicated here.

As it turns out, the elliptical do go up to that line, but most of them are below.

But they're somewhere in between and so a great majority of elliptical galaxies are supported by velocity anisotropy.

Of course, disks are always supported by rotation, even if the larger elliptical component is supported by anisotropy.

Galaxy, Andromeda has two elliptical dwarf elliptical companions and if you stretch the picture at high contrast you can see that For one of them NGC205, the isophotes are twisted and actually a little boxy, which is another interesting question.

You can think of an elliptical galaxy isophote as say single period wave as you go in the azimuth.

So the, it was found that elliptical galaxies are more metal rich near the middle than on the outside skirts.

Dark matter halos are fluffier and dominate more at large radii. This is certainly true in elliptical galaxies as well.

What's shown on the lower left is set of isophotes for some elliptical galaxy and major minor axis are drawn.

He works out at the same gym as us. he's that guy whose always on the elliptical staring at people.

We already talked about gas in elliptical galaxies so whereas spiral galaxies have plenty of interstellar medium, cold one, hydrogen mostly.

The way we quantify structure of elliptical galaxies is first by measuring their radial brightness profiles, so called surface brightness profiles.

I did not plot globular clusters and elliptical, non ellipticals as individual points, just indicated where are they in this diagram.

Because the moon doesn't have an atmosphere you can do an elliptical orbit and miss it by 10 feet if you want.

And you can obviously see that elliptical galaxies really do look like ellipses, although, ellipticity may be changing as a function of radius.

Those can be understood in terms of merging, random merging of pieces into an elliptical galaxy will both anisotropize g its velocity dis , dispersion.