Detalles de publicación
PP 019029
The VLT-FLAMES Tarantula Survey. XXX. Red stragglers in the clusters Hodge 301 and SL 639.
(1) Instituto de Astrof\'isica de Canarias, E-38205 La Laguna, Tenerife, Spain
(2) Universidad de La Laguna, Dpto. Astrof\'isica, E-38206 La Laguna, Tenerife, Spain
(3) ESA, European Space Astronomy Centre, Apdo. de Correos 78, E-28691 Villanueva de la Cañada, Madrid, Spain
(4) UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
(5) Argelander-Institut für Astronomie der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
(6) Lennard-Jones Laboratories, Keele University, Staffordshire, ST5 5BG, United Kingdom
(7) School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom
(8) Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, United Kingdom
(9) Zentrum f\"{u}r Astronomie der Universit\"{a}t Heidelberg, Astronomisches Rechen-Institut, M\"{o}nchhofstr. 12-14, 69120 Heidelberg, Germany
(10) Heidelberger Institut f\"{u}r Theoretische Studien, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
(11) Departamento de F\'isica Te\'orica e Experimental, Universidade Federal do Rio Grande do Norte, CP 1641, Natal, RN, 59072-970, Brazil
(12) Institute of astrophysics, KU Leuven, Celestijnlaan 200D, 3001, Leuven, Belgium
(13) Anton Pannenkoek Institute for Astronomy, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
We estimate physical parameters for the late-type massive stars observed as part of the VLT-FLAMES Tarantula Survey (VFTS) in the 30 Doradus region of the Large Magellanic Cloud (LMC). The observational sample comprises 20 candidate red supergiants (RSGs) which are the reddest ((B−V) > 1 mag) and brightest (V < 16 mag) objects in the VFTS. We use optical and near-IR photometry to estimate their temperatures and luminosities, and introduce the luminosity-age diagram to estimate their ages. We derive physical parameters for our targets, including temperatures from a new calibration of (J−Ks)0 colour for luminous cool stars in the LMC, luminosities from their J-band magnitudes (thence radii), and ages from comparisons with state-of-the-art evolutionary models. We show that interstellar extinction is a significant factor for our targets, highlighting the need to take it into account in analysis of the physical parameters of RSGs. We find that some of the candidate RSGs could be massive AGB stars. The apparent ages of the RSGs in the Hodge 301 and SL 639 clusters show a significant spread (12-24 Myr). We also apply our approach to the RSG population of the relatively nearby NGC 2100 cluster, finding a similarly large spread. We argue that the effects of mass-transfer in binaries may lead to more massive and luminous RSGs (which we call `red stragglers') than expected from single-star evolution, and that the true cluster ages correspond to the upper limit of the estimated RSG ages. In this way, the RSGs can serve as a new and potentially reliable age tracer in young star clusters. The corresponding analysis yields ages of $24^{+5}_{−3}$ Myr for Hodge 301, $22^{+6}_{−5}$ Myr for SL 639, and $23^{+4}_{−2}$ Myr for NGC 2100.