Terzan 1 is a globular cluster about 21,800 light-years from Earth in the constellation of Scorpius.
This Hubble image shows Terzan 1, a globular cluster located some 21,800 light-years away in the constellation of Scorpius. Image credit: NASA / ESA / Hubble / R. Cohen.
Terzan 1, also known as ESO 455-23 and Terzan 1966, is a heavily obscured globular cluster located in the constellation Scorpius.
Of the 150 globular clusters belonging to our Milky Way Galaxy, about 70 lie within 13,000 light-years from the Galactic center where their density tends to peak.
Terzan 1 has the smallest projected distance to the Milky Way’s center among all known globulars. It is only 4,200 light-years from the center but 21,800 light-years from Earth.
“Terzan 1 is one of 11 globular clusters that were discovered by the Turkish-Armenian astronomer Agop Terzan between 1966 and 1971 when he was working in France, based mostly at Lyon Observatory,” Hubble astronomers explained.
“Somewhat confusingly, 11 globular clusters are numbered from Terzan 1 to Terzan 12.”
“This is due to an error made by Terzan in 1971, when he rediscovered Terzan 5 — a cluster he had already discovered and reported back in 1968 — and named it Terzan 11. He published its discovery alongside those of Terzan 9, 10 and 12.”
“He quickly realized his mistake, and attempted to have Terzan 12 renamed as Terzan 11. Unfortunately, he did not make it clear that Terzan 5 and Terzan 11 were one and the same, although another astronomer, Ivan Robert King, did publish a note to try and clear up the confusion.”
“Nowadays, most papers recognize the original Terzan 5 and Terzan 12, and accept the oddity that there is no Terzan 11.”
Terzan 1 is not a new target for Hubble — an image of the cluster was released back in 2015, taken by Hubble’s Wide Field Planetary Camera 2 (WFPC2).
The newly-released image is a composite of separate exposures acquired by Hubble’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) instruments.
It is based on data obtained through one visible light and two infrared filters. The color results from assigning different hues to each monochromatic image associated with an individual filter.
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