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Astron. Astrophys. 353, 944-951 (2000)

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Luminosity function and mass segregation in M92

G. Andreuzzi 1, R. Buonanno 1, F. Fusi Pecci 2, G. Iannicola 1 and G. Marconi 1

1 Astronomical Observatory of Rome, via di Frascati 33, 00040 Monteporzio Catone, Roma, Italy (gloria@coma.mporzio.astro.it)
2 Astronomical Observatory of Bologna, via Zamboni 33, 40126 Bologna, Italy

Received 26 May 1999 / Accepted 27 October 1999


We present WFPC2-HST observations of the lower main sequence of the galactic globular cluster M92 (NGC6341), extending down to V [FORMULA] 27. Our data, which cover a region of the cluster extending from the very center out to r [FORMULA] 380 arcsec, show that the slope of the luminosity function becomes flatter going towards the center of the cluster, as expected if M92 is a dynamically relaxed system.

The slope of the inferred power-law mass function we computed ranges from x [FORMULA] 0.7 for the field centered at r = 18.61 core radii, to x [FORMULA] 0.3 for the annular field centered at r = 10.61 core radii, where a value of 14 arcsec has been used for the core radius of M92. Such a result, obtained without making any use of dynamical theoretical models, shows that segregation effects are at work in M92.

Key words: Galaxy: globular clusters: individual: M92 – stars: low-mass, brown dwarfs – stars: luminosity function, mass function

Send offprint requests to: G. Andreuzzi

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© European Southern Observatory (ESO) 2000

Online publication: January 18, 2000