Pre-Disintegration Study of Long-Period Comet C/2021 A1 (Leonard)

GARCÍA, R.S.; FERNÁNDEZ-LAJÚS, E.; DI SISTO R.P.; GIL-HUTTON, R.A.

Congreso; Asteroids, Comets, Meteors ACM 2023; 2023

Comet C/2021 A1 (Leonard), hereafter “Leonard”, was discovered on January 2021 with a magnitude of V 19 at ∼ a heliocentric distance rH = 5 au [1]. Leonard is a long-period comet, withperihelion distance q = 0.61 au, eccentricity e = 1.0001 and inclination i = 132.6°, reaching perihelion in January 2022. Considering the pre-entry orbital elements corrected for planetary perturbations to epoch 1900, it is correct to conclude that Leonard is not a dynamically new comet, having passed through the planetary system ∼10⁵ yr ago [3]. The comet attained naked-eye visibility in late 2021and then displayed spectacular gas and dust tails. However, Leonard became photometrically unstable in December 2021 and January 2022 [2]. The morphology also changed, becoming more diffuse and with “the tail being more prominent than the head” on January 22, 2022 at rH ∼ 0.74 au.In his work, Jewitt [3] presented images of the Leonard disruption, considering that the completedisintegration of the nucleus was near mid-December, 2021 explaining that the rotational instability driven by out-gassing torques offers the most plausible mechanism for the disruption.