Page last updated Oct 18, 2017|
A magnitude 19(?) compact galaxy (type S0?) in Bo÷tes (RA 14 30 37.5, Dec +11 52 35)
Physical Information: No distance estimate appears to be available for SDSS J143037.48+115234.8. Given its very small size (about 0.05 by 0.05 arcmin) it is probably very distant, but since its distance is unknown, its physical size is also unknown.
Above, a 1.4 arcmin wide SDSS image centered on J143037.48+115234.8
Also shown are PGC 51844 and 4126457 and NGC 5647
Below, a 0.6 arcmin wide SDSS image of the galaxy and part of PGC 51844 and NGC 5647
WORKING HERE: Clean up PanSTARRS image, edit Physical Information
Terzan 5 (= J174805-244648)
Discovered (1968) by Agop Terzan
A magnitude 12.8 globular cluster in Sagittarius (RA 17 48 05, Dec -24 46 48)
Physical Information: Physical diameter about 5 to 6 light years. Distance about 17 to 20 thousand light years; located near the central bulge of the Milky Way's nucleus. Its central half parsec (about 1.6 light years) contains about a million solar masses, which represents a stellar density about ten million times greater than in the region near our Sun. Like most globular clusters, Terzan 5's stars are mostly around 12 billion years old, but an unusual episode of intense star formation about 4.5 billion years ago produced a large number of relatively young (and therefore relatively massive and bright) stars with a much higher metallicity (the fraction of the stars' mass that is anything other than hydrogen and helium). For this reason it is sometimes thought to be a captured dwarf galaxy, rather than a globular cluster; but a recent study of the motions of 36 pulsars located within the cluster indicates that it does not contain a large central mass (characteristic of most galaxies), so it is probably just an ancient remnant of the formation of our galaxy which happens to have had an encounter with another object of large mass near the time of its more recent burst of star formation.
Above, a 12 arcmin wide DSS image centered on Terzan 5
Below, a 2.4 arcmin wide DSS image of the cluster
Below, a 1.2 by 1.8 arcmin wide PanSTARRS image of the cluster
Below, a 1.5 by 3.0 arcmin wide HST image of the cluster (Image Credit NASA/ESA/Hubble/F. Ferraro)
Below, the central 1.2 by 1.5 arcmin portion of the image above (Image Credit as above)