The Radial and Rotational Velocity of $\zeta$ Ophiuchi

TL;DR

This study precisely measures the radial velocity of $$ Oph through spectroscopic monitoring, refining its value to better understand its space motion and potential past association with a pulsar, contributing to stellar kinematics knowledge.

Contribution

The paper provides a new, precise measurement of $$ Oph's radial velocity, improving previous estimates and aiding in the understanding of its origin and motion.

Findings

Radial velocity of $$ Oph is 12.2$\u00b1$3.3 km/s.

Projected rotational velocity is 432$\u00b1$16 km/s.

No significant variability in radial velocity was detected.

Abstract

We present the results of our spectroscopic monitoring campaign of $\zeta$ Oph, carried out at the University observatory Jena with the spectrograph FLECHAS between July 2015 and September 2016. The main aim of the project is to determine the radial velocity of the star precisely, as a wide range of radial velocity measurements of $\zeta$ Oph are given in the literature. Beside the proper motion and parallax, the radial velocity is an important input parameter for the calculation of the space motion of the star. $\zeta$ Oph is considered to be a runaway star and potential former companion of the progenitor star of the pulsar PSRJ1932+1059, which both may have been located in a binary system and were then released during a supernova explosion about 1 Myr ago in the Upper Scorpius OB association. For the calculation that the pulsar and $\zeta$ Oph could have been at the same place, a radial velocity of $-$9.0 km/s for $\zeta$ Oph was used in the literature. By analysing the hydrogen and helium lines in 48 FLECHAS spectra, we determined the radial velocity of $\zeta$ Oph to be 12.2$\pm$3.3 km/s and the projected rotational velocity to 432$\pm$16 km/s with no indication for variability.