Comments on: Astronomers Locate High Energy Emissions from the Crab Nebula

By: Jon Hanford

Jon Hanford — Sat, 30 Aug 2008 11:54:57 +0000

I'm curious as to whether the Fermi GR telescope can measure the polarization of gamma rays. It certainly easily picked up the Crab pulsar in its' first released all-sky image, although this was a given, taking into account its' high gamma ray output. Fermi's higher resolution also may give us more insight into the Crab pulsars' jet emissions (whether it can detect GR polarity or not).

By: quantum_flux

quantum_flux — Sat, 30 Aug 2008 01:03:51 +0000

Good stuff!

By: cjameshuff

cjameshuff — Fri, 29 Aug 2008 17:44:36 +0000

The surface of a neutron star isn't neutron matter, but rather a layer of iron. Very smooth iron.

This doesn't necessarily mean it's shiny metal, though…it's possible the pressure or electromagnetic conditions on the surface modify its appearance. For example, solid oxygen is normally pale blue, but under sufficient pressure turns dark red. And in sufficiently intense magnetic fields, electron orbitals deform. I have no idea what stretching its orbitals into spindles would do to the appearance of iron…

That's for a neutron star that's cooled sufficiently for reflection to be the main way to see it. Neutron stars that actually exist would be blue or violet to the naked eye…assuming you survive the x-rays it radiates most of its energy as, and aren't blinded by the UV.

By: Feenixx

Feenixx — Fri, 29 Aug 2008 16:48:11 +0000

@DaveM:
I don't know about the visibility – it'd be very small, anyway, about 40km across, at twice the weight of our sun… and very hot.
It would certainly be very smooth. I read somewhere that if something or somebody would land on it, they'd be spread out evenly across the surface….

By: DaveM

DaveM — Fri, 29 Aug 2008 16:26:55 +0000

I always try to imagine what an object like this would look like if we could see it directly from close quarters.

What colour is a neutron star – I suppose we might call this material 'Neutronium' (a cold one – I'm talking about reflected light!)?

At a rotation speed of 30 rps, would the shape be a flattened ellipsoid?

And how smooth would the surface of a neutron star be? I imagine it .. very smooth indeed – with variations from a perfect sphere being measured at atomic scales!