On 28 July 2006, Victor Afanasiev from the Russian Academy of Sciences observed the spectrum of a faint meteor as it burned up in the Earth’s atmosphere. He recorded the event using a 6 metre telescope in the remote Zelenchuksky region of Russia near the border with Georgia.
It soon became clear to Afanasiev that this was no ordinary meteor. It hit the atmosphere at 300 kilometres per second, an order of magnitude faster than most other particles.
That’s puzzling. The Earth moves around the galactic center at about 220 km/s and so the meteor’s origin cannot easily be explained by reference to the Milky Way.
So where did it come from? Afanisiev and a few pals worked out that it appeared to come from the direction in which the Earth and the Milky Way is travelling towards the centre of our local group of galaxies. “This fact leads us to conclude that we observed an intergalactic particle, which is at rest with respect to the mass centroid of the Local Group and hich was “hit” by the Earth,” they say.
That’s an extraordinary claim. We can see alotta stuff out there beyond the galaxy but actually interacting with it ain’t common.
This meteor had other interesting properties which raise important questions. The team calculated that it must have been several centimetres in size, an order of magnitude bigger than ordinary meteors. Why so big?
The spectra shows the particle was made of iron, magnesium, oxygen, iodine and nitrogen. This kind of stuff, the metals in particular, form inside stars. How could it have ended up in intergalactic space?
Is this kinda dust evenly spread or in clumps? If it is clumpy, can we spot it? Would it, for example, show up in the WMAP images of the cosmic microwave background? That would be a wasp in the picnic basket.
What we need is more data. Anybody else seeing any intergalactic meteors out there?
Ref: arxiv.org/abs/0712.1571: Detection of an Intergalactic Meteor Particle with the 6-m Telescope