2014/09/09 by Eric E. Mamajek, Cameron P. M. Bell · 3 citations
Physics and Astronomy · #Astrometry #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Classical mechanics #Gamma-ray bursts and supernovae #Kinematics #Orbit (dynamics) #Physics #Radial velocity #Sigma #Stars #Stellar, planetary, and galactic studies #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stu1894
Accepted for publication in MNRAS; 13 pages, 6 figures and 5 tables
arxiv created 2014/09/09 · openalex publication_date 2014/10/16 · arxiv updated 2015/06/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Binks & Jeffries and Malo et al. have recently reported Li depletion boundary (LDB) ages for the Pictoris moving group (BPMG) which are twice as old as the oft-cited kinematic age of 12 Myr. In this study, we present (1) a new evaluation of the internal kinematics of the BPMG using the revised Hipparcos astrometry and best available published radial velocities, and assess whether a useful kinematic age can be derived, and (2) derive an isochronal age based on the placement of the A-, F-, and G-type stars in the colour-magnitude diagram (CMD). We explore the kinematics of the BPMG looking at velocity trends along Galactic axes, and conducting traceback analyses assuming linear trajectories, epicyclic orbit approximation, and orbit integration using a realistic gravitational potential. None of the methodologies yield a kinematic age with small uncertainties using modern velocity data. Expansion in the Galactic X and Y directions is significant only at the 1.7 and 2.7 levels, and together yields an overall kinematic age with a wide range (13-58 Myr; 95 per cent CL). The A-type members are all on the zero-age main sequence, suggestive of an age of >20 Myr, and the loci of the CMD positions for the late-F-and G-type pre-main-sequence BPMG members have a median isochronal age of 22 Myr ( 3 Myr statistical, 1 Myr systematic) when considering four sets of modern theoretical isochrones. The results from recent LDB and isochronal age analyses are now in agreement with a median BPMG age of 23 3 Myr (overall 1 uncertainty, including 2 Myr statistical and 2 Myr systematic uncertainties).