Additional TWA Members? : Spectroscopic verification of kinematically selected TWA candidates

Abstract

We present spectroscopic measurements of the 23 new candidate members of the TW Hydrae Association from Makarov & Fabricius (2000). Based on Halpha and Li 6708 A strengths together with location on a color-magnitude diagram for Hipparcos TWA candidates, we found only three possible new members (TYC 7760-0835-1, TYC 8238-1462-1, and TYC 8234-2856-1) in addition to the already known member, TWA 19. This eliminated most of the candidates more distant than 100 pc. Three Tycho stars, almost certainly members of the Lower Centaurus Crux association, are the most distant members of the TWA. A claim of isotropic expansion of TWA has to be re-evaluated based on our new results. Generally, one cannot identify new members of a diffuse nearby stellar group based solely on kinematic data. To eliminate interlopers with similar kinematics, spectroscopic verification is essential.

4 (journal) pages, 3 figures, accepted in A&A. (US Letter size)

Cited by in corpus (23)

• A catalogue of young runaway Hipparcos stars within 3kpc from the Sun
• Characterization of Dusty Debris Disks: the IRAS and Hipparcos Catalogs
• A Moving Cluster Distance to the Exoplanet 2M1207 B in the TW Hya Association
• A High-Precision NIR Survey for RV Variable Low-Mass Stars
• The Gemini NICI Planet-Finding Campaign: The Frequency of Planets around Young Moving Group Stars
• Dusty Debris Disks as Signposts of Planets: Implications for SIRTF
• On the age of the TW Hydrae Association and 2M1207334-393254
• Pre-main sequence spectroscopic binaries suitable for VLTI observations
• The Carina-Near Moving Group
• Stars with Photometrically Young Gaia Luminosities Around the Solar System (SPYGLASS) I: Mapping Young Stellar Structures and their Star Formation Histories
• The VLT/NaCo Large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits: I- Sample definition and characterization
• The epsilon Chamaeleontis young stellar group and the characterization of sparse stellar clusters
• Distance and Kinematics of the TW Hydrae Association from Parallaxes
• Radial-velocity survey of members and candidate members of the TW Hydrae association
• A Widely-Separated, Highly-Occluded Companion to the Nearby Low-Mass T Tauri Star TWA 30
• ACRONYM III: Radial Velocities for 336 Candidate Young Low-Mass Stars in the Solar Neighborhood, Including 78 Newly Confirmed Young Moving Group Members
• Rotation periods for stars of the TW Hydrae association
• ROSAT X-ray Spectral Properties of Nearby Young Associations: TW Hydrae, Tucana-Horologium, and the beta Pic Moving Group
• Color Gradients Detected in the HD 15115 Circumstellar Disk
• HD 199143 and HD 358623: Two Recently Identified Members of the Beta Pictoris Moving Group
• The Astrometric-Spectroscopic Binary System HIP 50796: An Overmassive Companion
• The young binary HD 102077: Orbit, spectral type, kinematics, and moving group membership
• Flare stars in the TW Hydrae association: The HIP 57269 system