The Closest Globular Neighbor
Messier 4 is one of the closest globular clusters to Earth. Visually, it is distinguished by a 'bar' of stars running through its center, first noted by William Herschel. Because it sits behind heavy clouds of interstellar dust in the Scorpius region, its light is significantly reddened, giving it a unique warm hue compared to other globulars.
Imaging Challenges
- • Shooting through the high atmospheric extinction due to its southern declination.
- • Dealing with the intense glare from nearby Antares if framing for a wide field.
- • Resolving the central bar structure against the dense background of the Milky Way.
M4 contains white dwarf stars that are among the oldest known objects in our galaxy, estimated to be 13 billion years old.