Roberto Gorelli points our attention at some recently published meteor related papers.

Lunar impact flashes

This paper will be published in the Monthly Notices of the Royal Astronomical Society: “Temperatures of lunar impact flashes: mass and size distribution of small impactors hitting the Moon.” by C. Avdellidou and J. Vaubaillon.

Lunar impact flashes have been monitored over the last 20 years for determining the mass frequency distribution of near-Earth objects in the cmˆaA¸Sdm size range. In ˘this work, using telescopic observations in R and I band from the NELIOTA database, impact flash temperatures are derived. They are found to range between approximately 1,300 and 5,800 K. In addition, it is also found that temperature values appear to have a distribution significantly broader than a Gaussian function, therefore making it difficult to estimate the impact flash luminous energy by assigning an  average temperature. By measuring the flash temperatures and assuming a black body emission, here we derive the energy of the impacts. We also study the potential link of each event to individual meteoroid streams, which allows us to assign an impact velocity and therefore constrain the projectile mass. Impactor masses are found to range between a few to hundreds of grams, while their sizes are just of few centimetres following a size frequency distribution similar to other studies.

You can download this paper for free: (12 pages).


The Geminid parent body: (3200) Phaethon

This paper appeared in Planetary & Space Science, Special Issue on Asteroid (3200) Phaethon and Meteoroids: “Arecibo Radar Observations of Near-Earth Asteroid (3200) Phaethon During the 2017 Apparition”, by Patrick A. Taylor, Edgard G. Rivera-Valentín, Lance A.M. Benner, Sean E. Marshall, Anne K. Virkki, Flaviane C.F. Venditti, Luisa F. Zambrano-Marin, Sriram S. Bhiravarasu, Betzaida Aponte-Hernandez, Carolina Rodriguez Sanchez-Vahamonde and Jon D. Giorgini.

We report Arecibo S-band (2380 MHz; 12.6 cm) radar observations of near-Earth asteroid (3200) Phaethon during the December 2017 apparition when Phaethon passed within 0.07 au of Earth. Radar images with a resolution of 75 m per pixel reveal a roughly spheroidal shape more than 6 km in diameter at the equator with several discernible surface features hundreds of meters in extent. These include a possible crater more than 1 km across located below 30◦ latitude and a roughly 600-m radar-dark region near one of the poles. Overall, the radar images of Phaethon are reminiscent of those of (101955) Bennu, target of the OSIRIS-REx mission. As such, the shape of Phaethon is suspected to have an equatorial ridge similar to the top-shaped models of several other radar-observed near-Earth asteroids as well as the optical images of (162173) Ryugu returned by the Hayabusa2 spacecraft. Preliminary analysis of the radar data finds no satellites and gives no indication of a dusty coma at the time of these observations.

You can download this paper for free:  (18 pages).


Sun approaching asteroids and meteor streams

The third paper appears in Astronomy and Astrophysics: “Debris of asteroid disruptions close to the Sun”, by Quanzhi Ye and Mikael Granvik.

The under-abundance of asteroids on orbits with small perihelion distances suggests that thermallydriven disruption may be an important process in the removal of rocky bodies in the Solar System. Here we report our study of how the debris streams arise from possible thermally-driven disruptions in the near-Sun region. We calculate that a small body with a diameter & 0.5 km can produce a sufficient amount of material to allow the detection of the debris at the Earth as meteor showers, and that bodies at such sizes thermally disrupt every ∼ 2 kyrs. We also find that objects from the inner parts of the asteroid belt are more likely to become Sun-approacher than those from the outer parts. We simulate the formation and evolution of the debris streams produced from a set of synthetic disrupting asteroids drawn from Granvik et al. (2016)’s near-Earth object population model, and find that they evolve 10–70 times faster than streams produced at ordinary solar distances. We compare the simulation results to a catalog of known meteor showers on Sun-approaching orbits. We show that there is a clear overabundance of Sun-approaching meteor showers, which is best explained by a combining effect of comet contamination and an extended disintegration phase that lasts up to a few kyrs. We suggest that a few asteroid-like Sun-approaching objects that brighten significantly at their perihelion passages could, in fact, be disrupting asteroids. An extended period of thermal disruption may also explain the widespread detection of transiting debris in exoplanetary systems.

You can download this paper for free: (18 pages).


Older meteor library news: