The VMC survey. XVIII. Radial dependence of the low-mass, 0.55-0.82 Mo stellar mass function in the galactic globular cluster 47 Tucanae

CH. ZHANG + 6 COAUTORES; A.E. PIATTI; +7 COAUTORES

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2015 vol. 815

0004-637X

We use near-infrared observations obtained as part of the Visible and Infrared Survey Telescopefor Astronomy (VISTA) Survey of the Magellanic Clouds (VMC), as well as two complementaryHubble Space Telescope (HST) data sets, to study the luminosity and mass functions as a function ofclustercentric radius of the main-sequence stars in the Galactic globular cluster 47 Tucanae. The HSTobservations indicate a relative deficit in the numbers of faint stars in the central region of the clustercompared with its periphery, for 18.75 ≤ m F606W ≤ 20.9 mag (corresponding to a stellar mass rangeof 0.55 < m ∗ /M < 0.73). The stellar number counts at 6.7 from the cluster core show a deficit for17.62 ≤ m F606W ≤ 19.7 mag (i.e., 0.65 < m ∗ /M < 0.82), which is consistent with expectations frommass segregation. The VMC-based stellar mass functions exhibit power-law shapes for masses in therange 0.55 < m ∗ /M < 0.82. These power laws are characterized by an almost constant slope, α,although with a possibly declining trend toward the cluster?s inner regions. The radial distributionof the power-law slopes α thus shows evidence of the importance of both mass segregation and tidalstripping, for both the first- and second-generation stars in 47 Tuc.