The porous envelope and circumstellar wind matter of the closest carbon star, CW Leonis

TL;DR

This paper discusses recent dramatic changes in CW Leonis, a nearby carbon star, which may indicate its transition from the Asymptotic Giant Branch to the pre-planetary nebula phase, providing insights into late stellar evolution.

Contribution

It reports new observational evidence of rapid changes in CW Leonis, highlighting potential early signs of stellar phase transition and emphasizing the need for continued monitoring.

Findings

Appearance of a red compact peak at the stellar position

Radial beams resembling features of the Egg Nebula

Decadal variations in light curves and halo brightness

Abstract

Recent abrupt changes of CW Leonis may indicate that we are witnessing the moment that the central carbon star is evolving off the Asymptotic Giant Branch (AGB) and entering into the pre-planetary nebula (PPN) phase. The recent appearance of a red compact peak at the predicted stellar position is possibly an unveiling event of the star, and the radial beams emerging from the stellar position resemble the feature of the PPN Egg Nebula. The increase of light curve over two decades is also extraordinary, and it is possibly related to the phase transition. Decadal-period variations are further found in the residuals of light curves, in the relative brightness of radial beams, and in the extended halo brightness distribution. Further monitoring of the recent dramatic and decadal-scale changes of this most well-known carbon star CW Leonis at the tip of AGB is still highly essential, and will help us gain a more concrete understanding on the conditions for transition between the late stellar evolutionary phases.