Physical Properties

At a distance of 83 kpc (about 270'000 light-years), NGC 2419 is one of the most distant globular clusters, more distant than the Large Magellanic Cloud. Until recently it was thought not to belong to the halo of the Milky Way, which is why it was nicknamed the «Intergalactic Wanderer». ^{[145, 196]}

Measurements by the Hubble Space Telescope and the Gaia Space Telescope showed that NGC 2419 orbits the center of the Milky Way in a nearly polar orbit of about 53 kpc to 98 kpc (173'000 to 320'000 light years) and takes about four billion years to do so. This and the common sense of rotation around the Milky Way make it very likely that this globular cluster once belonged to the Sagittarius dwarf elliptical galaxy (Sgr dSph, Sag DEG). ^[302]

Usually, stars within globular clusters show very similar properties, such as age and metal content (any element heavier than helium in astronomy), since the stars formed at the same time. It was also assumed that this similarity would hold true for the helium content of each star within the globular cluster. Studies of NGC 2419 using the Hubble Space Telescope showed that this assumption is not always true. This globular cluster features two distinct populations of red giants, one of which is unusually rich in helium. Other elements such as B. nitrogen also show strong differences in the individual stars. This population of helium-rich stars was found primarily at the center of the globular cluster, and they also appear to rotate differently from the other population. This raises questions as to whether both stellar populations formed together or are of different origins. ^[301]

Finder Chart

NGC 2419 is located in a star-poor region in the constellation Lynx, about 7° north of bright star Castor (α Geminorum). The best viewing time is November to April.

Visual Observation

320 mm Aperture: Two stars of about the same brightness serve as pointers, along which the «Intergalactic Wanderer» follows. The globular cluster NGC 2419 can be seen as a globular nebula, but not resolved into individual stars. The center appears a little punctiform brightened. — 12.5" f/4.5 Ninja-Dobsonian, Glaubenberg, 25. 3. 2022, Eduard von Bergen

400 mm Aperture: At low magnification (21 mm Tele Vue Ethos, 85x) the globular cluster appears as a round nebula in the extension of two bright mag 7 stars. One of them is a binary. A very beautiful sight. With the two other, slightly fainter stars at the other end, it looks a bit like an arrow flying toward the globular cluster. When the air is still, one believes one can see small stars in the globular cluster. In the 16 mm Nagler eyepiece (112x) these turn out to be fine neighboring stars and stand out more clearly. The cluster itself remains nebulous with a slightly brighter center. The view is most beautiful in the 9 mm Nagler eyepiece (200x). The contrast from the globular cluster to the sky background appears best here and the specialty with the two bright stars offers a nice overall picture. Even at higher magnifications (up to 450x), the globular cluster cannot be resolved into individual stars. It is too dark for that. — Taurus T400 f/4.5 Dobsonian, Glaubenberg, SQM-L 20.9, 25. March 2022, 21:00 CET, Bernd Nies