Padova University
Padova University
Astronomy Department
Physics & Astronomy Dep.
Asiago
Asiago Observatory
Padova Observatory
Padova Observatory

Exoplanets & Stellar Populations Group


UNIVERSITY OF PADOVA - DEPARTMENT OF PHYSICS AND ASTRONOMY "GALILEO GALILEI"
vicolo Osservatorio 3, 35122 Padova - Italy tel. +39.049.827.8211     fax. +39.049.827.8212
                                                                                       

Half size CM-diagram preview

NGC 6121
M 4
C 1620-264


DSS Image

Photometric Data
(gzipped)


Globular Cluster parameters
IPM parameters
PM parameters
KS parameters

Observed fields preview



NGC 6121 (M 4)

This cluster is the closest GGC, located approximately at ∼2.2 kpc from the Sun, though, due to the large reddening caused by the nebulosity in Scorpio-Ophiuchus, it has an apparent visual distance modulus larger than NGC 6397. The reddening is differential, though (as in the case of NGC 4372) it is homogeneously distributed in space. The mean sequences of the CMD can be improved using an appropriate second order polynomial fit to the reddening distribution, at least on the two fields shown. The stars from the southern field have been plotted as darker dots; they are located on the redder (more reddened) part of the CMD. The two most recent CMD of M 4 are in Ibata et al. (1999) and Pulone et al. (1999), who present HST studies of the faint part of the MS and of the WD sequence. Other recent CMDs from the RGB tip to below the MSTO are in Alcaino et al. (1997), who presented an U, B, V, I CCD photometry, and Kanatas et al. (1995), who obtained a composite (B, V) CMD from V∼12 to V∼25.

Last Update May 2000