Issue |
A&A
Volume 497, Number 2, April II 2009
|
|
---|---|---|
Page(s) | 371 - 378 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361/200810555 | |
Published online | 18 February 2009 |
Multi-color photometry in wide field of the Galactic globular cluster NGC 3201 *,**
1
Instituto de Astronomía, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile e-mail: vkravtsov@ucn.cl
2
Sternberg Astronomical Institute, University Avenue 13, 119899 Moscow, Russia
3
Isaac Newton Institute of Chile, Ministerio de Educación de Chile, Casilla 8-9, Correo 9, Santiago, Chile e-mail: inewton@terra.cl, falvarad@eso.org
4
ESO - European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile e-mail: gmarconi@eso.org
Received:
9
July
2008
Accepted:
24
December
2008
Aims. This paper aims at further studying one of the nearby Galactic globular clusters (GCs), NGC 3201. It is known to experience notable irregular variability of reddening across its face. By relying on our previous studies and findings and by developing them, we focus on the brighter sequences of the color-magnitude diagram (CMD) and on the cluster's characteristics.
Methods. We carried out and analyzed new
multi-color photometry of NGC 3201 in UBVI reaching below the
turnoff point in all passbands in a fairly large cluster field,
about . To achieve more reliable results and
conclusions, we reduced the negative impact of the irregularly
varying reddening and contamination by field stars.
Results. With this aim
we first estimated mean reddening in different zones of the studied
cluster field and then took its variations into account, by reducing
them to the same level. We estimated metallicity of NGC 3201 using a
new metallicity indicator related to U-based CMDs, recently
proposed by us. We find [Fe/H] dex, which
falls between extreme estimates of the cluster's metallicity
obtained using different methods or indicators. Also, the location
of the RGB bump on the branch corresponds to [Fe/H]
dex. We isolate 73 probable blue straggler (BS)
candidates, the largest population found in NGC 3201 so far. They
are more centrally concentrated than the lower red giants at the
99.2% level. Their position in the two-color diagram assumes that
presumably none of them belongs to BSa of collisional origin. The
luminosity function (LF) of the RGB and its features in the low part
of the branch are examined and discussed. We also resolve some of
the contradictory results of previous publications.
Key words: globular clusters: general / globular clusters: individual: NGC 3201
© ESO, 2009
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