Kappa Crucis, Jewel Box |Right Ascension||12 : 53.6 (h:m)
|Declination||-60 : 20 (deg:m) |Visual Brightness||4.2 (mag)
|Apparent Dimension||10 (arc min)| Discovered by Nicholas Louis
de Lacaille on March 25, 1752. This cluster was one of the
finest open clusters discovered by Nicholas Louis de Lacaille
when he was in South Africa during 1751-1752. This cluster is
one of the youngest known, with an estimated age of only 7.1
million years (Sky Catalog 2000). Its hottest star is of
spectral type B0. According to Burnham, the 3 brightest stars
are blue giants of mag 5.75 and spectral type B9, mag 5.94 and
type B3, and mag 6.80/B2, while the fourth brightest star is a
mag 7.58 M2 red supergiant. Another mag 5.7/spectral type A1
star is probably also a member, another white supergiant: This
star would be the brioghtest of the cluster at about absolute
magnitude -7.7 (83,000 solar luminosities). Situated close to
the cluster is a huge dark area of the sky, right within the
band of the Milky Way: the Coal Sack. This