NGC 458 is anopen cluster located in the constellationTucana. It was discovered on September 6, 1826, byJames Dunlop. It was also observed byJohn Herschel andDeLisle Stewart. It was described byDreyer as "pretty faint, large, round, very gradually brighter middle". It was also noted in the second Index Catalogue that it was "probably a cluster, extremely small, close, no nebulosity seen by D.S. (DeLisle Stewart)."[3] At an aperture of 31 arcseconds, its apparent V-band magnitude is 11.73, but at this wavelength, it has 0.12 magnitudes ofinterstellar extinction.[2]
NGC 458 is quite young, at about 140 million years old. Its estimated mass is2.6×104M☉, and its total luminosity is1.24×105L☉, leading to a mass-to-luminosity ratio of 0.21M☉/L☉. However, the dynamical mass may be inaccurate due to the small stellar sample used in the analysis.[2] All else equal, older star clusters have higher mass-to-luminosity ratios; that is, they have lower luminosities for the same mass.[2]
Media related toNGC 458 at Wikimedia Commons
