Astron. Astrophys. 361, 73-84 (2000)

4. Colour-magnitude diagrams (CMDs)

In Fig. 3 the resulting V-(V-I)-CMDs are presented for all the fields. In these diagrams the main sequence population is the most prominent feature. In F3 and F4 a red branch parallel to the main sequence is visible. It is produced by He-burning evolved stars distributed along the line of sight with increasing reddening. In the fields F1 and F2 this branch is scarcely populated. The CMDs of F3 and F4 show a small group of stars brighter than V 15-15.5 on the blue side of the main sequence. In Sect. 7, these stars will be shown to be tracers for the inner spiral arm (I).

Fig. 3a-d. The V-(V-I) CMDs of the fields F1 a , F2 b , F3 c , F4 d . For all fields, the main sequence population dominates the diagram. The red branch parallel to the main sequence can be identified with evolved stars. The line shows the blue edge of main sequence (see text for details)

© European Southern Observatory (ESO) 2000

Online publication: September 5, 2000
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