Yet another possible meteorite fall in Norway! Can we tell who its parents were?

On December 9, 2013 by Mike

On December 4th at 18:33:17 UT, a bright fireball was witnessed by a number of people across southern Norway. Roughly as bright as a quarter moon, eyewitness and infrasound reports have been analysed by Steinar Midtskogen to produce an estimate of the trajectory and burst location. Using Steinar’s results, I’ve calculated an orbit for the object and compared it to the orbits of more than half a million known asteroids to see if we could say something about where this object came from.

Using the method of Southworth & Hawkins, I constructed a spreadsheet that calculates their dissimilarity criterion (Dsh) as well as the Jopek modification (Dh) to Dsh. Doing this, tells us something about the similarity between orbits. The smaller the Dsh (or Dh) parameter, the more similar the orbits.

I started off first looking at 60,000 known asteroids and set a cutoff of 0.25 on my Dh. In doing so, I identified 3 candidate parent bodies: 2007 XN (Dh=0.19), 2012 FE54 (Dh=0.22), 5731 Zeus (Dh=0.25). Plotting up these three orbits alongside the Odda meteor (turquoise path) gives the following…

Odda_SimilarOrbits1

You can see the similarity between the orbits, but, what happens if we increase our orbit database by a factor of 10? Well, we can now get a bit pickier and lower our Dh cutoff to 0.2. When we do this, we find the following possible candidate parents: 2009 AK – Dh=0.14, 2007 XN- Dh=0.19, 2010 YD3 – Dh=0.19, 2009 ST103 – Dh=0.19

Odda_similarorbits2So, can we make a guess at a parent body for the Odda meteor? Unfortunately, I’d have to say no. Not without further work. We’ve identified orbits that are similar to the orbit of the Odda meteor but there’s no smoking gun. If, however, we were to go out on a limb and suggest that 2009 AK and 2007 XN have orbits similar enough to be possible parent bodies, what would that tell us? Well, 2007 XN is listed as a potentially hazardous asteroid (PHA) which is pretty cool. Both asteroids have absolute magnitudes of about 20 which means that they’re about 350m in diameter. But neither have been characterized so we can’t say anything about their composition. So, really, the question is not what the potential parent bodies can tell us about the Odda meteor(ites), but what the Odda meteor(ites) could tell us about its parent body. Unfortunately, snow on the ground means that a search will have to wait until the spring…

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