Largest Lens Ever Discovered

K Tanmay writes "A team of Astronomers have found a natural lens capable of resolving details as fine as 10 microarcseconds across - equivalent to seeing a sugar cube on the Moon, from Earth. The lens comprises of a cloud of interstellar gas, and works on the principle of scintillation; where the clumpiness inside a cloud of gas creates a density change thus bending and focusing the light. This technique, dubbed 'Earth-Orbit Synthesis', will be first used to study black holes in distant quasars, so don't expect spectacular wallpaper replacing images. There's also an interview with Dr. Hayley Bignall, an astronomer from the Joint Institute for Very Long Baseline Interferometry in Europe (JIVE), where she discusses the concept of using interstellar scintillation to get observations that we could never measure from here on earth." Update: 02/22 18:23 GMT by T : That wikipedia link had led to the wrong place; here's the definition for arcsecond if you still want to read it.

Comments

Uhm...

[Black Parrot]

Maybe we need a new method for determining the distance between "scintillation" and "arcsecond".

but...

[UnMutedChaos]

If we can't see a sugar cude on the moon right now, so how can we tell how this lens is focusing if at all? A few small defects in hubbles lens blured it bad, some thing this big would have alot of area for defects. to me that seams like it would make a very bad lens. So my real question is? how is this usefull?

Re:but...

[jafiwam]

Hubble is used to generate images where quality is measured by pixels per area of the target, and making sure all the pixels are faithfully in the correct place on the image.

There are lots of other types of information that can be gathered; a full spectrum and spectral lines, shifted or not. Pulsing or changes in the amount of light, and so on.

So this type of lens extends the reach of devices that gather non-image type data by gathering light from a WIDE area and allowing us to pick it up on earth.

So think of it as a really really huge radio dish, not as a big hunk of glass.

An error in the illustration?

[beeplet]

The caption to one of the illustrations reads:

At some times of the year, both the Earth and the cloud 'lens' are moving in the same direction, and the observed variations are slow, but six months later they are moving in opposite directions and the variations are fast.

while the illustrations clearly shows a a wave which is of constant frequency but of varying amplitude. I believe the caption is correct...

And a related complaint: what is the point of including a picture of the ring nebula with the caption:

The Ring Nebula, although not useful imaging through, has the suggestive look of a far-away telescope lens.

I guess when you can't come up with any images actually related to the topic, you might as well throw in some pretty Hubble pictures for those who aren't going to read the text anyway.

Black Holes in Distant Quasars

[whig]

It will be interesting to see whether such phenomena are actually found.

Some scientists have theorized that quasars are *not* distant galaxies, but stars with a peculiar lens-effect that causes a very large perceived red shift.

Part of the problem with the idea that the red shift is a doppler effect is that the observed quasars are apparently all in a relatively spherical arrangement about the Earth, thus implying that the Earth must be the center of the observed universe.

It could be that this is just an artifact of observation: we see the quasars as equidistant from Earth because we are perceiving them from Earth. But it is very strange and implies a problem with the theory.

A paper on this subject is available.

Pulsars can do as good or better than this...

[Scott Ransom]

High precision timing of millisecond pulsars (which accounts for every single rotation of a pulsar over the course of several years) can make observations with astrometric (i.e. positional) errors of several micro arcseconds.

An excellent example was published in Nature in 2001. Here is a preprint. The work describes the timing of the nearby (~450 lt-yrs) millisecond pulsar J0437-4715. The proper motion (movement across the sky) and parallax (apparent motion on the sky due to the earth's orbit) of the pulsar were measured to extreme precision, and a new test of General Relativity was also given.

PS: IAAPA (I am a pulsar astronomer)

lenses, resolution and radio (and Carl Sagan!)

[sdedeo]

Interstellar scintillation is really neat and interesting. You can use its properties to measure the nature of the interstellar medium indirectly -- for example, from the dispersion of a pulsar signal (a pulsar emits something a little like a square wave pulse in the radio, which is then smudged and smeared out as different wavelengths scintillate differently.)

I studied I.S. a little bit awhile back. Carl Sagan did some work on scintillation; the scintillation effect can pull out a distant radio signal by gathering in rays from a lot of different directions and accidentally throwing them right at you. The famous WOW signal, I believe, was investigated as an example of scintillation from a big cloud much like the ones described in the article.

It is interesting to see this technique used to do radio astronomy. Most of the times when you encounter a natural lens, it is sufficiently weird that you use the observation to analyse the lens itself, and not what it happens to be magnifying. Gravitational lenses are interesting in large part because you can try to figure out the distribution of dark matter in the lens itself -- and not because you can use it to "see into" the object being lensed. These lenses are not exactly perfect optics -- they're more like balls of glass, which distort and differentially magnify something behind.

But I'm not as familiar any more with radio astronomy. It is definitely possible that we understand enough about the properties of the ISM that the more interesting problem of figuring out the properties of the background object is open for work. Very cool!