New fundamental parameters for the inner disk open cluster Lyngå 11

Monthly Notices of the Royal Astronomical Society

Mermilliod

et al. 2007

We present CCD BVI photometry for the southern open cluster NGC 2489 and its surrounding field. The sample consists of 2182 stars measured in an area of 13.6 × 13.6 arcmin2, extending down to V∼ 21.5. These data are supplemented with CORAVEL radial‐velocity observations for seven red giant candidates. A cluster angular radius of 6.7 ± 0.6 arcmin, equivalent to 3.5 ± 0.3 pc, is estimated from star counts carried out inside and outside the cluster region. The comparison of the cluster colour–magnitude diagrams with isochrones of the Padova group yields E(B−V) = 0.30 ± 0.05, E(V−I) = 0.40 ± 0.05 and V−MV= 12.20 ± 0.25 for log t= 8.70 (t= 500+130−100 Myr) and Z= 0.019. NGC 2489 is then located at 1.8 ± 0.3 kpc from the Sun and 25 pc below the Galactic plane. The analysis of the kinematical data allowed us to confirm cluster membership for six red giants, one of them being a spectroscopic binary. A mean radial velocity of 38.13 ± 0.33 km s−1 was derived for the cluster red giants. The properties of a sample of open clusters aligned along the line of sight of NGC 2489 are examined.

Section: Data Handlingmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

CCD BVI photometry and Coravel observations of stars in the open cluster NGC 2489

Monthly Notices of the Royal Astronomical Society

Mermilliod

et al. 2007

“…We compared the stellar density radial profile of NGC 2236 with those of other open clusters we observed using both the same CCD and telescope: NGC 2194 (Piatti et al 2003a); Tr 5 (Piatti et al 2004a); NGC 2324 (Piatti et al 2004b); Tombaugh 1 (Piatti et al 2004c); NGC 6318 (Piatti, Clariá & Ahumada 2005); Lyngå 11 (Piatti, Clariá & Ahumada 2006a); NGC 5288 (Piatti, Clariá & Ahumada 2006b) and NGC 2489 (Piatti et al 2007). We previously normalized these cluster profiles to the distance and field star density of NGC 2236, and expressed the stellar densities in units of number of stars per square parsec.…”

Section: Structural Cluster Featuresmentioning

confidence: 99%

NGC 2236: a moderately metal-poor open cluster of Hyades-like age located beyond the Perseus spiral arm

Monthly Notices of the Royal Astronomical Society

Parisi

et al. 2007

New CCD photometry in the Washington system C and T1 passbands down to T1∼ 18.5 mag in the field of the northern open cluster NGC 2236 is presented. T1 magnitudes and C−T1 colours for a total of 1162 stars within an area of 13.6 × 13.6 arcmin2 were measured. These CCD data were supplemented with photoelectric CMT1T2 photometry of 13 red giant candidates. The comparison of the cluster (T1, C−T1) colour–magnitude diagram with theoretical isochrones computed for the Washington system yields E(C−T1) = 1.10 ± 0.10 and for log t= 8.80 (t= 600+100−40 Myr) and Z= 0.008. The derived E(C−T1) value implies E(B−V) = 0.55 ± 0.05. NGC 2236 is then located at 2.5 ± 0.5 kpc from the Sun beyond the Perseus spiral arm and at ∼10.8 kpc from the Galactic centre. A cluster angular diameter of 9.4 arcmin, equivalent to 6.8 pc, was estimated from star counts both within and outside the cluster field. We also derived from the stellar density profile a cluster core radius of rc= 1.7 arcmin (1.2 pc) and an annular corona of Δrc= 1.8rc (2.2 pc). Five independent Washington abundance indices yield a mean cluster metallicity of [Fe/H]=−0.3 ± 0.2, which is not only in reasonably good agreement with the one obtained from the isochrone fit, but also compatible with the existence of a radial abundance gradient in the Galactic disc. We examined the properties of a sample of 20 known open clusters aligned along the line‐of‐sight to NGC 2236. Berkeley 27 appears as the farthest and oldest cluster of the studied sample.

“…Our goal is to obtain good‐quality charge‐coupled device (CCD) photometric data, not only to produce a larger sample of studied open clusters, but also to determine their fundamental parameters accurately, using the most recent family of theoretical isochrones. We have already reported results on the relatively young clusters NGC 2194, 2324 and 6318 (Piatti, Clariá & Ahumada 2003a, 2004a, 2005a), on the Hyades‐like cluster Lyngå 11 (Piatti, Clariá & Ahumada 2006), on the intermediate‐age clusters NGC 2627 and Tombaugh 1 (Piatti, Clariá & Ahumada 2003b, 2004b), and on the old, metal‐poor anticentre cluster Trumpler 5 (Piatti, Clariá & Ahumada 2004c).…”

Section: Introductionmentioning

confidence: 99%

First estimates of the fundamental parameters of the relatively bright Galactic open cluster NGC 5288

Monthly Notices of the Royal Astronomical Society

Ahumada

2006

In this paper we present charge‐coupled device (CCD) images in the Johnson B and V and Kron–Cousins I passbands for the previously unstudied open cluster NGC 5288. The sample consists of 15 688 stars reaching down to V∼ 20.5. The cluster appears to have a relatively small but conspicuous nucleus and a low‐density extended coronal region. Star counts carried out in 25 × 25 pixel2 boxes distributed throughout the whole observed field allowed us to estimate the angular core and corona radii as ∼1.3 and 6.3 arcmin, respectively. Our analysis suggests that NGC 5288 is moderately young and probably more metal‐rich than the Sun. Adopting the theoretical metal content Z= 0.040, which provides the best global fit, we derive an age of 130+40−30 Myr. Simultaneously, we have obtained colour excesses E(B−V) = 0.75 and E(V−I) = 0.95 and an apparent distance modulus V−MV= 14.00. The law of interstellar extinction in the cluster direction is found to be normal. NGC 5288 is located at 2.1 ± 0.3 kpc from the Sun beyond the Carina spiral feature and ∼7.4 kpc from the Galactic Centre. The cluster metallicity seems to be compatible with the cluster position in the Galaxy, given the recognized radial abundance gradient in the disc. For the first time, in this paper we determine the basic parameters for the open cluster NGC 5381, situated in the same direction as NGC 5288. This determination was reached by using CCD VI data published almost a decade ago by Pietrzyński et al. (1997) for NGC 5381. The properties of some open clusters aligned along the line of sight of NGC 5288 are examined. The properties of clusters of similar ages to NGC 5288 are also looked into. Evidence is presented that these did not form mainly along the spiral arms but rather in the thin Galactic disc (Z∼±100 pc).