Messier 2 by Hubble Space Telescope; 3.5 'view. Image credit: NASA/STScI/WikiSky

  The globular cluster Messier 2 is one of the greatest known. It is a concentration of stars attracted mutually by their gravity, orbiting near the galactic nucleus. It is about 37,500 light years away, and has a diameter of about 175 light years. The age of the cluster is estimated at about 13 million years.

  The brightest stars in the cluster are red and yellow giants of magnitude 13.1, one of the richest and most compact globular clusters, ranking second in the density scale (this scale consists of 12 degrees of density). 

  Messier 2 has a curious peculiarity. To him belongs a variable star of the type RV Tauri that oscillates between the 12,5 and the 14 magnitude in about 67 days, or some more, since its period fluctuates. When it is at its maximum brightness it can give a different appearance to the cluster.

  More details here: Messier 2

Messier 2 Globular Cluster imaged from Talent, OR. Image source: (1)

NGC 2438

NGC 2438 and the Calabash Nebula. Image source: (2)

  NGC 2438 is a planetary nebula, the gaseous envelope that a dying star similar to the Sun, a class of stars of several billions of years that has already exhausted its central reserve of hydrogen fuel. It is located about 3 thousand light-years away, within the limits of the constellation of the Puppis. 

 NGC 2438, a beautiful planetary nebula that appears superimposed on the field. One may think that he is part of that star army and walks with them through space, but the truth seems to be different. While the cluster moves with respect to us at 44 km /s, NGC 2438 does so at 77 km/s, which places it in an earlier plane. In addition, if it belonged to the cluster would be too young to have formed a planetary nebula (although there are no examples of stars that die at a too early age).