Orbital eccentricity of the symbiotic star MWC 560

TL;DR

This paper measures the rotational velocity of the red giant in MWC 560 and estimates its orbital eccentricity, providing insights into the star's dynamics and variability.

Contribution

It offers the first spectroscopic measurement of the red giant's rotational velocity and estimates the orbital eccentricity using tidal interaction models.

Findings

Projected rotational velocity vsini = 8.2 +/- 1.5 km/s

Rotational period estimated between 144-306 days

Orbital eccentricity estimated between 0.68-0.82

Abstract

We present projected rotational velocity measurements of the red giant in the symbiotic star MWC 560 (V694 Mon), using the high-resolution spectroscopic observations with the FEROS spectrograph. We find that the projected rotational velocity of the red giant is vsini = 8.2 +/- 1.5 km/s, and estimate its rotational period to be P_rot = 144-306 days. Using the theoretical predictions of tidal interaction and pseudosynchronization, we estimate the orbital eccentricity e=0.68-0.82. We briefly discuss the connection of our results with the photometric variability of the object.