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How to confound an astronomer

Generally, or so the folklore goes, if you want to annoy an astronomer who is busy talking excitedly about some new observation (or theory), just say something along the lines of "fascinating, but what about magnetic fields?" The truth is, a lot of the time we just don't know as much as we'd like to about what magnetic fields are doing and just how they are influencing what we see. That's why we keep looking and keep modelling, one day we'll get there. Anyway, a group of astronomers at Berkeley have been looking for magnetic fields in giant molecular clouds and have found what they describe as a magnetic slinky in Orion.

The Orion molecular cloud (OMC) is absolutely stunning when you see it in photographs as it is absolutely huge (it is also quite faint so you can't see it with your eyes, which is a real shame). Centred on a region of star formation within our own Galaxy, the complex contains loops, spurs and clouds, all glowing faintly red due to emission from warm hydrogen gas.

A magnetic
A magnetic "slinky" in Orion CREDIT: Saxton, Dame, Hartmann, Thaddeus; NRAO/AUI/NSF

It is thought that magnetic fields can shape gas clouds (and jets), but it is very difficult to detect these fields as they are often very weak. This is one example of where radio telescopes are particularly useful as they can detect the signals that characterise magnetic fields. What the researchers found when looking at the OMC using the Green Bank Telescope (GBT) at a frequency of 1420 MHz, the radio frequency at which neutral hydrogen emits, was that the field was orientated towards us on one side of a filament and away from us on the other. This is a dead givaway for a helical field, something like a corkscrew shape, hence the slinky analogy. Now, there are other possible explanations for the observed field orientations (as the authors themselves point out in the press release) but this seems the most likely one. Wow, slinkys in space, whatever next?!

Posted by Megan on Friday 13th Jan 2006 (22:33 UTC) | Add a comment | Permalink


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