NGC 6440 is a typical giant, obscure, and polluted globular cluster that formed and orbited within the Milky Way’s bulge.
This web image shows the globular cluster NGC 6440 located 27,625 light-years away in the constellation Sagittarius. Image credits: NASA / ESA / CSA / Webb / P. Freire / M. Cadelano / C. Pallanca.
NGC 6440 is located approximately 8,470 parsecs (27,625 light-years) away in the constellation Sagittarius.
This globular cluster, also known as C 1746-203 or GCl 77, was discovered by German-born British astronomer William Herschel on May 28, 1786.
NGC 6440 has an apparent magnitude of about 10 and a diameter of about 6 arcmin.
“Globular clusters like NGC 6440 are collections of ancient stars that are roughly spherical and held together by gravity,” said Dr. Mario Caderano of the University of Bologna and his colleagues.
“They can be found throughout the galaxy, but often live in suburban areas.”
“They contain hundreds of thousands to millions of stars that are on average about a light-year away, but they can be as close as the size of our solar system.”
“NGC 6440 is known to be a high-mass, metal-rich star cluster orbiting within the galactic bulge, a dense, nearly spherical region of old stars located inside the Milky Way.”
Images of NGC 6440 were obtained using 2023 data. Webb’s near-infrared camera (NIRCam) is part of an observational program to explore the stars within the cluster and study the details of the cluster’s pulsars.
“Pulsars are highly magnetized rotating neutron stars that emit beams of electromagnetic radiation from their magnetic poles,” the astronomers said.
“To us, that beam appears as short bursts or pulses as the star rotates. Pulsars rotate very quickly.”
Astronomers have measured the fastest pulsars spinning at more than 716 revolutions per second, but in theory, pulsars could spin as fast as 1,500 revolutions per second before slowly losing energy and falling apart.
“The new data show the first evidence from Webb observations of variations in helium and oxygen abundance in stars within globular clusters,” the researchers said.
“These results open the door to future detailed investigations of other star clusters within the Galactic Bulge. This is due to the fact that the stars within the cluster are quite densely packed, and the interstellar space between them Considering the strong reddening caused by dust, this has not been possible in other telescope facilities until now.”
The team paper was published in the magazine astronomy and astrophysics.
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Mario Caderano other. 2023. JWST reveals variations in helium and water abundance in the bulge globular cluster NGC 6440. A&A 679, L13; doi: 10.1051/0004-6361/202347961
Source: www.sci.news
