(meteorobs) Hypervelocity meteors

Pavol Habuda bzucino at yahoo.com
Sun Dec 30 12:53:19 EST 2007


A had some time to read that article. Here are some notes on that one.

1. Spectrum is lack of green forbidden line 557.5 nm. It means, either meteor
was too slow (slow than 30 km/s) or indeed very fast, with height of ending
above 115 km. Article proposes meteor height about 100 km. It is nonsense, in that
height green line must be very prominent in spectrum.

2. Na dublet around 579 nm is missing. This could be argument for interstellar
origin -- Na as volatile component was vapored and removed by cosmic rays.
Alternative explanation could be built on presence of many strong Fe lines
in spectra. It could be iron meteoroid in fact.

3. I don`t understand much to method of estimating velocity of meteor.
I comprehended they want to use line curvature on plate for counting velocity.
   If we see meteor perpendicular to us, is it not moving radial. This meteor is
90 degrees from radiant (so it cannot be connected to radiant on place of 
local group). Meteor moving from us has negative velocity, meteor moving
to us have velocity positive. Image 3b shows different curve than we expect.
So, image is not graph of radial velocity at all -- we even suppose size
of CCD much smaller than a few degrees.

So, we need article with more precise explanation of reduction of spectra.
Authors maybe suppose trivial other thing that ours. Maybe the are completely 
lost. Interstellar/intergalactic meteoroid could be great success for science.
One have to be optimistic, but not much. We must be aware of difference
between science and pious wish.


Pavol Habuda




====================================================================================
That is correct. AFAIK, this would be the first detection of meteoroids that were
uneqivocally not part of the solar system, never mind the galaxy.

Wayne

-------------- Original message -------------- 
From: Francisco Ocaña <albireo3000 at yahoo.es> 

> Hello list, 
> 
> before reading this article I thought that meteors at v>73km/s were 
> uncommon. What do you know/think about this topic? 
> 
> 
> arXiv:0712.1571 
> Date: Mon, 10 Dec 2007 19:11:42 GMT (401kb) 
> 
> Title: Detection of an intergalactic meteor particle with the 6-m telescope 
> Authors: V.L. Afanasiev (1), V.V. Kalenichenko (2), I.D. Karachentsev 
> (1) ((1) 
> Special Astrophysical Observatory Russian Academy of Sciences (2) 
> Astronomical Observatory, Kyiv Taras Shevchenko University) 
> Categories: astro-ph 
> Comments: 9 pages, 6 EPS figures 
> Journal-ref: Astrophysical Bulletin, 2007, v. 62, p. 301-310 
> \\ 
> On July 28, 2006 the 6-m telescope of the Special Astrophysical 
> Observatory 
> of the Russian Academy of Sciences recorded the spectrum of a faint 
> meteor. We 
> confidently identify the lines of FeI and MgI, OI, NI and 
> molecular-nitrogen 
> N_2 bands. The entry velocity of the meteor body into the Earth's 
> atmosphere 
> estimated from radial velocity is equal to 300 km/s. The body was 
> several tens 
> of a millimeter in size, like chondrules in carbon chondrites. The 
> radiant of 
> the meteor trajectory coincides with the sky position of the apex of the 
> motion 
> of the Solar system toward the centroid of the Local Group of galaxies. 
> Observations of faint sporadic meteors with FAVOR TV CCD camera 
> confirmed the 
> radiant at a higher than 96% confidence level. We conclude that this meteor 
> particle is likely to be of extragalactic origin. The following important 
> questions remain open: (1) How metal-rich dust particles came to be in the 
> extragalactic space? (2) Why are the sizes of extragalactic particles 
> larger by 
> two orders of magnitude (and their masses greater by six orders of 
> magnitude) 
> than common interstellar dust grains in our Galaxy? (3) If extragalactic 
> dust 
> surrounds galaxies in the form of dust (or gas-and-dust) aureoles, can such 
> formations now be observed using other observational techniques (IR 
> observations aboard Spitzer satellite, etc.)? (4) If inhomogeneous 
> extragalactic dust medium with the parameters mentioned above actually 
> exists, 
> does it show up in the form of irregularities on the cosmic microwave 
> background (WMAP etc.)? 
> \\ ( http://arxiv.org/abs/0712.1571 , 401kb) 
> 
> 
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