A study of runaway stars originating in the Scorpius-Centaurus-Lupus association

¹ Astrophysical Institute, Friedrich-Schiller-University Jena, Schillergäßchen 2, 07745 Jena, Germany
² Byurakan Astrophysical Observatory after V. A. Ambartsumian, 0213 Byurakan, Aragatsotn Province, 378433, Armenia
³ Astrophysical Research Laboratory of Physics Institute, Yerevan State University, 1 Alek Manukyan St., Yerevan, Armenia

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 7 August 2025
Accepted: 29 December 2025

Abstract

Context. Runaway stars are OB-type stars with an unusually high space velocity, and they originate in a stellar cluster. OB runaways are produced by dynamical ejection or by a supernova explosion in a multiple system, and a hybrid scenario is also possible.

Aims. Being the closest OB association to Earth, the Scorpius-Centaurus-Lupus association is an extraordinarily interesting subject of research, and it has been identified as the parent cluster of several known runaway stars. Our aim with this work is to find new runaway candidates originating in the Scorpius-Centaurus-Lupus association and its recently found subgroups using new Gaia data.

Methods. By tracing back in time the flight paths of all known OB-type stars within a 1.7 kpc radius around the Sun and those of the individual subgroups of Scorpius-Centaurus-Lupus, we intend to find close encounters between runaway candidates and the studied subgroups in order to find the likeliest parent group(s) for each candidate. As input data, we largely use Gaia DR3 and HIPPARCOS astrometry as well as radial velocities from the literature.

Results. We present eight runaway candidates originating from Scorpius-Centaurus-Lupus (3D space velocity 20–67 km s⁻¹), of which at least three were previously known as such. Additionally, we find 22 walkaway stars (10–20 km s⁻¹), i.e., “slower” runaway stars that may have been ejected from their parent group by the same mechanisms as their faster counterparts.

Conclusions. We identified five new runaway stars. Among the total number of eight runaway stars (including one, ζ Oph, that is likely produced by the binary supernova scenario), up to two might have been ejected dynamically, whereas most were produced in a binary-supernova scenario. Further traceback studies may find some of the neutron stars born in these supernovae, and some of them are possibly responsible for the ⁶⁰Fe found in Earth’s crust. We confirm that the runaway star ζ Oph and pulsar PSR B1706-16 originated from Scorpius-Centaurus-Lupus in a recent nearby binary supernova, most probably from subgroup SigMA 15, which has more than one thousand member stars.