Detection of an intergalactic meteor particle with the 6-m telescope

TL;DR

This paper reports the detection of a faint meteor with spectral evidence suggesting an extragalactic origin, using the 6-m telescope, and discusses implications for intergalactic dust and cosmic observations.

Contribution

First spectral detection of an intergalactic meteor particle using a large telescope, providing evidence for extragalactic dust and raising new astrophysical questions.

Findings

Spectral lines of FeI, MgI, OI, NI, and N2 detected in meteor

Meteor velocity estimated at 300 km/s, indicating extragalactic origin

Radiant aligns with the Solar system's motion toward the Local Group

Abstract

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.)?