Observation of the $\alpha$ Carinid meteor shower 2020 unexpected outburst

Abstract

We present observations of the sudden outburst of the $\alpha$ Carinid meteor shower recorded with the Southern Argentina Agile MEteor Radar-Orbital System (SAAMER-OS) near the South Toroidal sporadic region. The outburst peaked between 21 UT and 22 UT on October 14, 2020 and lasted 7 days $(199^{\circ}\leq\lambda_{\odot}\leq 205^{\circ})$ with a mean Sun-centered geocentric ecliptic radiant of $\lambda_{g}-\lambda_{\odot}=271^{\circ}.04$, $\beta_{g}=-76^{\circ}.4$, and a geocentric speed of 33.3 km s$^{-1}$. Assuming a mass index value of $s=2.0$, we compute a peak 24 hour-average flux of 0.029 met. km$^{-2}$ hr$^{-1}$ to a limit of 9th magnitude, which is equivalent to a zenithal hourly rate (ZHR) of 5.7, and comparable to other established showers with similar mass indices. By further estimating the peak fluxes for other typical mass index values, we find that the outburst likely never exceeded a maximum ZHR of $\sim44$, well below the activity of other strong showers. The mean orbital elements resemble those of a short-period object: $a=3.5\pm0.1$ au, $q\simeq 1$ au, $e=0.72\pm0.02$, $i=55^{\circ}.8\pm0^{\circ}.3$, $\omega=1^{\circ}\pm 173^{\circ}$, $\Omega=21^{\circ}.7$, and are similar to those derived for two previous shower outbursts observed with SAAMER-OS at high southern ecliptic latitudes. Using the $D^{\prime}$ criterion did not reveal a parent object associated with this shower in the known object catalogues.