161 research outputs found
Discovery of a Meteor of Interstellar Origin
The first interstellar object, `Oumuamua, was discovered in the Solar System
by Pan-STARRS in 2017, allowing for a calibration of the abundance of
interstellar objects of its size m. One would expect a much higher
abundance of smaller interstellar objects, with some of them colliding with
Earth frequently enough to be noticeable. Based on the CNEOS catalog of bolide
events, we identify the m meteor detected at 2014-01-08 17:05:34 UTC
as originating from an unbound hyperbolic orbit with 99.999\% confidence. We
infer that the meteor had an asymptotic speed of outside of the solar system. Its origin is
approximately towards R.A. and declination , implying that its initial velocity vector was away from the velocity of the Local Standard of Rest
(LSR). Its high LSR speed implies a possible origin from the deep interior of a
planetary system or a star in the thick disk of the Milky Way galaxy. The local
number density of its population is or
(necessitating 0.2 - 20 Earth masses of material to be ejected per local star).
This discovery enables a new method for studying the composition of
interstellar objects, based on spectroscopy of their gaseous debris as they
burn up in the Earth's atmosphere.Comment: 4 pages, 2 figures; submitted to ApJL; uncertainties update
Interstellar Meteors are Outliers in Material Strength
The first interstellar meteor larger than dust was detected by US government
sensors in 2014, identified as an interstellar object candidate in 2019, and
confirmed by the Department of Defense in 2022. Here, we describe an additional
interstellar object candidate in the CNEOS fireball catalog, and compare the
implied material strength of the two objects, referred to here as IM1 and IM2,
respectively. IM1 and IM2 are ranked 1 and 3 in terms of material strength out
of all 273 fireballs in the CNEOS catalog. Fitting a log-normal distribution to
material strengths of objects in the CNEOS catalog, IM1 and IM2 are outliers at
the levels of and , respectively. The random sampling
and Gaussian probabilities, respectively, of picking two objects with such high
material strength from the CNEOS catalog, are and . If IM2 is confirmed, this implies that interstellar meteors come from
a population with material strength characteristically higher than meteors
originating from within the solar system. Additionally, we find that if the two
objects are representative of a background population on random trajectories,
their combined detections imply that of all refractory elements are
locked in meter-scale interstellar objects. Such a high abundance seemingly
defies a planetary system origin.Comment: 5 pages, 3 figures, 1 table; accepted for publication in ApJ
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