Right ascension 02 39 59.3 Redshift 53 ± 9 km/s Apparent size (V) 17′.0 × 12′.6 Constellation Fornax | Declination −34° 26′ 57″ Type dE0 Magnitude 9.3 Apparent magnitude (V) 9.3 | |
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Distance 460 ± 30 kly (140 ± 10 kpc) Similar Sculptor Dwarf Galaxy, Carina Dwarf Spheroid, Draco Dwarf, Ursa Minor Dwarf, Leo II | ||
Evolution of star clusters in the fornax dwarf spheroidal galaxy
The Fornax Dwarf Spheroidal is an elliptical dwarf galaxy in the constellation Fornax that was discovered in 1938 by Harlow Shapley. He discovered it while he was in South Africa on photographic plates taken by the 24 inch (61 cm) Bruce refractor at Boyden Observatory, shortly after he discovered the Sculptor Dwarf Galaxy.
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The galaxy is a satellite of the Milky Way and contains six globular clusters; the largest, NGC 1049, was discovered before the galaxy itself. The galaxy is also receding from the Milky Way at 53 km/s. It mostly contains population II stars.
Globular clusters
Using the Hubble Space Telescope, scientists derived a color-magnitude diagram for Fornax 4, a globular cluster within this galaxy. Unlike the globular clusters Fornax 1, 2, 3, and 5, which have horizontal branches across a wide range of colors and include RR Lyrae variables, Fornax 4 is found to have only red in its horizontal branch. Fornax 4 is also ~3 Gyr younger than the other globular clusters. The color-magnitude diagram of Fornax 4 has a strong similarity to "young" galactic globular Ruprecht 106.
It is not known why spheroidals allow the formation of globular clusters like Fornax 4 and Terzan 7 (of Sagittarius dwarf) long after globular clusters ceased to form in the main body of the Galactic halo. Another possibility is that "young" globular clusters of the outer halo like Ruprecht 106 were originally formed in now defunct dwarf spheroidals.