NGC 2467

Lore & Background

NGC 2467 had long been considered the nucleus of the Puppis I association, but it does not represent a distinct open cluster. Instead, it is a superimposition of several stellar groups along the same line of sight with distinctly different distances and radial velocities. One group is young and very distant beyond Puppis OB2, while another nearer group with later-type stars lies at a similar distance as Puppis OB1. The region is dominated by the massive young star HD 64315, of spectral type O6. Two stellar clusters exist in the area: Haffner 19 (H19) and Haffner 18 (H18). H19 is a compact cluster containing a Strömgren sphere ionized by a hot B0 V-type star. H18 contains a very young star, FM3060a, that has just come into existence and is still surrounded by its birth cocoon of gas. The age of H19 is estimated at 2 Myr, while the age of H18 is somewhat controversial, with some considering it as young as only 1 Myr. The field also contains other early-type stars such as HD 64568, whose relationship with the clusters is unclear.

Reader's Guide

The H II region of NGC 2467 has been the target of various investigations to elucidate the process of star formation. Unresolved questions include understanding the degree to which stars already formed in such regions, especially massive O or B stars, can affect the future formation of stars: whether these pre-existing stars trigger the formation of others. One investigation using the Spitzer Space Telescope discovered 45 young stellar objects (YSOs), or protostars, in the region during its 'cold' mission. The YSOs are mostly along the edge of the HII region, and their concentrated distribution spatially correlated with ionization fronts provides evidence for triggered star formation. The newly forming protostars are concentrated in areas where the shock front driven in advance of the ionization front compresses the molecular gas. It has been estimated that H19, H18, and the S311 nebula are about 6.4 kpc, 5.9 kpc, and 6.3 kpc away, placing them in the Perseus Arm of the Milky Way. A significant discrepancy has existed between distances estimated kinematically versus photometrically. Regardless, H19 and H18 may be considered a binary cluster.

Did You Know?

• NGC 2467 is nicknamed the 'Skull and Crossbones Nebula' and has also been likened to a colorful mandrill.
• The region contains 45 young stellar objects discovered by the Spitzer Space Telescope during its cold mission.
• Haffner 19 and Haffner 18 may be considered a binary cluster, with estimated ages of 2 Myr and possibly as young as 1 Myr, respectively.
• The massive star HD 64315, of spectral type O6, dominates the region.