Publication Date:
2014-11-14
Description:
Whiting 1 is a member of the fast-growing group of young globular clusters in the Milky Way halo. Preliminary estimates of its fundamental parameters have been provided using optical photometry and low-resolution spectroscopy. In an attempt to strengthen our knowledge of Whiting 1, in this study we employ a complementary approach. Isochrone fitting method was applied on the near-infrared colour–magnitude diagram and yields an age t = 5.7 ± 0.3 Gyr, metallicity z = 0.006 ± 0.001 ([Fe/H] = –0.5 ± 0.1) and distance modulus ( m – M ) 0 = 17.48 ± 0.10. Our results confirm that Whiting 1 is a young and moderately metal-rich globular cluster. It is one of the youngest from the Sgr dSph. We fitted an Elson, Fall and Freeman (EFF) profile to the near-infrared number counts, and measured cluster core radius r c = 9.1 arcsec ± 3.9 arcsec. Two probable eclipsing variables in the cluster were found from multi-epoch V -band photometry. Finally, an unknown galaxy cluster was identified on our K versus ( J – K ) colour–magnitude diagram. It has a redshift z ~ 1, and it is located at about 1 arcmin from the centre of Whiting 1 at $\alpha _{\rm J2000} = 02^{\rm h} 02^{\rm m} 56 {.\!\!^{{\mathrm{s}}}}6$ , J2000 = –03°16 ' 09 ' ' , contaminating the cluster photometry.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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