Cameron P. M. Bell

Pre-main-sequence isochrones – II. Revising star and planet formation time-scales

CPMB is funded by a UK Science and Technology Facilities Council n(STFC) studentship. SPL is supported by an RCUK fellowship. nThe authors would like to thank Charles D. H. Williams nfor maintaining the Xgrid facilities at the University of Exeter nwhich were used to reduce the photometric data presented in this nstudy. The authors thank Amelia Bayo for bringing to our attention nthe important work on the λ Ori region published in Bayo net al. (2011) and Bayo et al. (2012) which we overlooked in nour original submission. The inclusion of these works does not nchange the results or conclusions of the paper. The authors also nthank the referee for useful comments and constructive suggestions nthat have greatly improved this work. This research has made nuse of data obtained at the Isaac Newton Telescope which is operated non the island of La Palma by the Isaac Newton Group n(ING) in the Spanish Observatorio del Roque de los Muchachos nof the Institutio de Astrofisica de Canarias. This research has also nmade use of archival data products from the Two-Micron All-Sky nSurvey (2MASS), which is a joint project of the University of nMassachusetts and the Infrared Processing and Analysis Center, nfunded by the National Aeronautics and Space Administration n(NASA) and the National Science Foundation.

A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood

We present a self-consistent, absolute isochronal age scale for young (< 200 Myr), nearby (< 100 pc) moving groups in the solar neighbourhood based on homogeneous fitting of semi-empirical pre-main-sequence model isochrones using the tau^2 maximum-likelihood fitting statistic of Naylor & Jeffries in the M_V, V-J colour-magnitude diagram. The final adopted ages for the groups are: 149+51-19 Myr for the AB Dor moving group, 24+/-3 Myr for the {beta} Pic moving group (BPMG), 45+11-7 Myr for the Carina association, 42+6-4 Myr for the Columba association, 11+/-3 Myr for the {eta} Cha cluster, 45+/-4 Myr for the Tucana-Horologium moving group (Tuc-Hor), 10+/-3 Myr for the TW Hya association, and 22+4-3 Myr for the 32 Ori group. At this stage we are uncomfortable assigning a final, unambiguous age to the Argus association as our membership list for the association appears to suffer from a high level of contamination, and therefore it remains unclear whether these stars represent a single population of coeval stars. nOur isochronal ages for both the BPMG and Tuc-Hor are consistent with recent lithium depletion boundary (LDB) ages, which unlike isochronal ages, are relatively insensitive to the choice of low-mass evolutionary models. This consistency between the isochronal and LDB ages instills confidence that our self-consistent, absolute age scale for young, nearby moving groups is robust, and hence we suggest that these ages be adopted for future studies of these groups. nSoftware implementing the methods described in this study is available from http: //www.astro.ex.ac.uk/people/timn/tau-squared/.

On the age of the β Pictoris moving group

Jeffries & Binks (2014) and Malo et al. (2014) have recently reported Li depletion boundary (LDB) ages for the {beta} Pictoris moving group (BPMG) which are twice as old as the oft-cited kinematic age of

Pre-main-sequence isochrones -- I. The Pleiades benchmark

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Pre-main-sequence isochrones – III. The Cluster Collaboration isochrone server

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{sigma} and 2.7{sigma} 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

A lithium depletion boundary age of 22 Myr for NGC 1960

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No evidence for intense, cold accretion on to YSOs from measurements of Li in T-Tauri stars

20Myr, 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 (

Modeling Transiting Circumstellar Disks: Characterizing the Newly Discovered Eclipsing Disk System OGLE LMC-ECL-11893

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A search for eclipsing binaries that host discs

3 Myr stat.,

Protoplanetary and Transitional Disks in the Open Stellar Cluster Ic 2395

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