Photometric study of five open star clusters

Abstract

U BVRI photometry of the five open clusters Czernik 4, Berkeley 7, NGC 2236, NGC 7226 and King 12 has been carried out using ARIES 104 cm telescope, Nainital. Fundamental cluster parameters such as foreground reddening E(B − V), distance, and age have been derived by means of the observed two colour and colour-magnitude diagrams, coupled to comparisons with theoretical models. E(B − V) values range from 0.55 to 0.74 mag, while ages derived for these clusters range from ∼10 to ∼500 Myr. We have also studied the spatial structure, mass function and mass segregation effects. The present study shows that evaporation of low mass stars from the halo of the clusters increases as they evolve.

Investigation of open clusters based on IPHAS and APASS survey data

“…The systematically higher values of our extinction estimates may be due to internal extinction within the cluster. Our distance estimates based on the (r−i, r), (Hα index, r), and (Hα index, Wri) diagrams agree well with each other: They also agree well with earlier published values except for the NGC6834 cluster for which we obtain a significantly greater distance (3115 ± 63, 3115 ± 120, and 2950 ± 59 based on (r − i, r), (Hα index, r), and (Hα index, Wri) diagrams, respectively) than inferred by Paunzen and Netopil (2006) where D(P ublished) are published distance estimates adopted from Paunzen and Netopil (2006); Meynet et al (1993); Phelps and Janes (1994); Lata et al (2014); Keller et al (2005) and D(r − i, i), D(r, Hα index), and D(Wri, Hα index) are our distance estimates based on the (r − i, i), (r, Hα index), and D(Wri, Hα index) diagrams, respectively (see Table 3).…”

“…Our extinction and distance estimates agree well with those reported in most of the standard cluster studies - Paunzen and Netopil (2006); Meynet et al (1993); Phelps and Janes (1994); Lata et al (2014); Keller et al (2005):…”

“…We converted the apparent distance moduli published by Meynet et al (1993) into distances using normal extinction law AV =3.1 EB−V . Given that the most accurate estimates of EB−V colour excesses are those inferred from (U −B, B−V ) colourcolour diagrams, we added to our sample the clusters with parameter estimates adopted from Phelps and Janes (1994); Keller et al (2005), and Lata et al (2014). The above authors first determined the EB−V colour excess by fitting cluster MS on the (U − B, B − V ) diagram to the standard ZAMS of Schmidt-Kaler (1982) or to the youngest isochrones of Girardi et al (2002), and then determined the distance modulus and age from the colour-magnitude diagrams.…”

“…; L14:Lata et al (2014); DAML02:Dias et al (2002); M93:Meynet et al (1993); PJ94:Phelps and Janes (1994); K05:Keller et al (2005); 3D map:Sale et al (2014) …”

ASteCA: Automated Stellar Cluster Analysis

“…The cluster that departs the most from the metallicity values assigned by AsteCA is NGC 6231. According to Tadross (2003) (Lata et al 2014). In this work, the authors employ a z = 0.02 Girardi isochrone to derive the reddening, which is why we associate a [Fe/H] = 0.0 value to it.…”