King 5 is located near the galactic plane
at
and
,
and it is designated also as OCL 384
and C0311+525 by IAU. Its diameter is estimated to be
about
.
A preliminary investigation was conducted by Phelps et al. (1994) who obtained
VI photometry for 1343 stars in a region of
.
This study revealed that King 5 is a cluster of the Hyades generation, with
an age around one billion years, derived from a morphological age estimator.
These authors do not report estimates for cluster distance and reddening.
Moderate resolution spectra for 24 stars in the field of King 5 have been obtained by Scott et al. (1995). From this analysis it emerges that King 5 belongs to the old thin disk population, and its rotational velocity around the galactic center (-52 km s-1) is consistent with Hron (1987) rotation curve at the cluster location.
On the base of the radial velocities 19 members have been singled out.
More recently Durgapal et al. (1998) published UBVRI photometry of King 5, inferring by comparison with solar metallicity isochrones an age slightly lower than 1 Gyr, a distance of 2 kpc and a reddening E(V-I)=0.94.
Finally it is worth recalling that the metal abundance of King 5 has been
determined by Friel et al. (1995) using medium resolution spectroscopy of
twelve giant stars. From this study [Fe/H] turns out to be (
),
half the solar value.
In this paper we combine together IR and optical photometry to obtain an estimate of the cluster fundamental parameters. We find that the cluster is 1.0 Gyr old.
The plan of the paper is as follows: Sect. 2 is devoted to the presentation of data acquisition and reduction; in Sect. 3 we discuss the morphology of the Color Magnitude Diagrams (CMDs) for different pass-bands; Sect. 4 is dedicated to the derivation of the color excess, while age and distance are inferred in Sect. 5. Finally our conclusions are summarized in Sect. 6.
Cluster | ![]() |
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Date | Exposure Times (sec) | |
(2000) | (2000) | J | K | ||
King 5 | 3 14 47 | 52 42 39 | Oct. 25, 1997 | 540 | 880 |
King 5 F1 | 3 14 23 | 52 48 39 | Oct. 27, 1997 | 480 | 620 |
King 5 F2 | 3 15 42 | 52 33 17 | Oct. 27, 1997 | 480 | 620 |
K5A | 3 14 40 | 52 42 51 | Oct. 25, 1997 | ||
K5B | 3 14 27 | 52 42 02 | Oct. 25, 1997 |
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Figure 1: The field covered in the region of King 5 by the optical photometry of Phelps et al. (1994). The inner region shows the mosaic of the four fields observed by us in the IR. North is up, East on the left |
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Figure 2: The CMD of King 5. The optical photometry (V-(V-I), upper left panel) is taken from Phelps et al. (1994). The IR photometry (lower panel) is that presented in this paper, whereas the upper right panel presents the derived CMD in V-(V-K). Filled circles represent cluster members on the basis of the radial velocity |
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