Nearby young stars selected by proper motion. I. Four new members of the Beta Pictoris moving group from the Tycho-2 catalog

TL;DR

This paper presents a method to identify new low-mass members of nearby stellar moving groups using proper motion data, successfully recovering known members and confirming three new Beta Pictoris group members from the Tycho-2 catalog.

Contribution

The study introduces a novel technique combining proper motion and photometry to efficiently find low-mass moving group members, demonstrated on the Beta Pictoris group with successful identification of new members.

Findings

Recovered all known Beta Pictoris members in the sample.

Identified three new low-mass group members.

Discovered a new common proper motion companion.

Abstract

We describe a procedure to identify stars from nearby moving groups and associations out of catalogs of stars with large proper motions. We show that from the mean motion vector of a known or suspected moving group, one can identify additional members of the group based on proper motion data and photometry in the optical and infrared, with minimal contamination from background field stars. We demonstrate this technique by conducting a search for low-mass members of the Beta Pictoris Moving Group in the Tycho-2 catalog. All known members of the moving group are easily recovered, and a list of 51 possible candidates is generated. Moving group membership is evaluated for 33 candidates based on X-ray flux from ROSAT, Halpha line emission, and radial velocity measurement from high-resolution infrared spectra obtained at Infrared Telescope Facility. We confirm three of the candidates to be new members of the group: TYC 1186-706-1, TYC 7443-1102-1, and TYC 2211-1309-1 which are late-K and early-M dwarfs 45-60pc from the Sun. We also identify a common proper motion companion to the known Beta Pictoris Moving Group member TYC 7443-1102-1, at a 26".3 separation; the new companion is associated with the X-ray source 1RXS J195602.8-320720. We argue that the present technique could be applied to other large proper motion catalogs to identify most of the elusive, low-mass members of known nearby moving groups and associations.