NGC 2587: A sparse open cluster projected on to a populous star field
We present CCD photometry in the Johnson U, B and V and Kron-Cousins I passbands for the open cluster NGC 2587. The sample consists of 4406 stars reaching down to V ∼ 21.0. We developed a new method to clean statistically the colour-magnitude diagrams. NGC 2587 appears to be a sparse, relatively bri...
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2009
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00358711_v397_n2_p1073_Piatti http://hdl.handle.net/20.500.12110/paper_00358711_v397_n2_p1073_Piatti |
| Aporte de: |
| Sumario: | We present CCD photometry in the Johnson U, B and V and Kron-Cousins I passbands for the open cluster NGC 2587. The sample consists of 4406 stars reaching down to V ∼ 21.0. We developed a new method to clean statistically the colour-magnitude diagrams. NGC 2587 appears to be a sparse, relatively bright open cluster, with a few tens of members projected on to a populous star field. The comparatively bright F7/8 II type star HD 70927, located close to the cluster centre, seems not to be a member. Our analysis suggests that NGC 2587 is slightly younger than the Hyades and probably of solar metallicity. A cluster radius of roughly 8 arcmin was estimated from the radial stellar density profile. From 18 probable cluster members with measured proper motions, we derive the following mean values for NGC 2587: μα = -4.3 ± 3.6 mas yr-1 and μδ = -2.5 ± 3.4 mas yr-1. Adopting the theoretical metal content Z = 0.02, which provides the best global fit, we derive a cluster age of 500+60 -50. Simultaneously, colour excesses E(B - V) = 0.10 and E(V - I) = 0.15 and an apparent distance modulus of V - MV = 12.50 are obtained. The interstellar extinction in the cluster direction is found to follow the normal law. NGC 2587 is located at a distance of (2.70 ± 0.70) kpc from the Sun and ∼9.8 kpc from the Galactic centre. © 2009 RAS. |
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