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

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.

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!