LO Pegasi: An investigation of multi-band optical polarization

TL;DR

This study presents the first multi-band optical polarization measurements of LO Peg, revealing high and variable polarization levels likely caused by scattering in circumstellar material or prominence-like structures.

Contribution

It provides the first polarimetric analysis of LO Peg, demonstrating significant polarization variability and suggesting scattering processes as the cause.

Findings

LO Peg exhibits high polarization among cool active stars.

Polarization levels are variable across BVR bands.

Scattering in circumstellar envelope or prominences likely causes polarization.

Abstract

We present BVR polarimetric study of the cool active star LO Peg for the first time. LO Peg was found to be highly polarized among the cool active stars. Our observations yield average values of polarization in LO Peg: $P_B =0.387\pm 0.004%$, $\theta_B = 88\deg\pm1\deg$; $P_V=0.351\pm0.004%$, $\theta_V=91\deg\pm1\deg$; and $P_R= 0.335\pm0.003%$, $\theta_R = 91\deg\pm1\deg$. Both the degree of polarization and the position angle are found to be variable. The semi-amplitude of the polarization variability in B, V and R bands are found to be $0.18\pm0.02$%, $0.13\pm0.01$% and $0.10\pm0.02$%, respectively. We suggest that the levels of polarization observed in LO Peg could be the result of scattering of an anisotropic stellar radiation field by an optically thin circumstellar envelope or scattering of the stellar radiation by prominence-like structures.