Stars resized for equality and color saturation adjusted in Adobe PhotoShop 7.0.
Diffraction spikes added with Noel Carboni's Astronomy Actions for Photoshop.
Description:
Discovered by John Herschel on November 3, 1831.
Perhaps the oldest known open star cluster in our Galaxy, with a calculated age of over 5 billion years (Alan Sandage's first estimate was even an age as high as 24 billion years, while Burnham claims 10-12 billion). It consists of about 120 stars, the hottest main sequence star of spectral type F2, the 10 brightest stars being yellow giants of spectral types G8 to K4 and luminosity class III, apparent magnitudes of about 12-14, corresponding to absolute magnitudes of 0 to +2.
