Astronomers utilizing the NASA/ESA Hubble Space Telescope have captured a stunning image of NGC 6426, an ancient globular star cluster located in the outer halo of the Milky Way galaxy. This remarkable structure contains two chemically distinct generations of stars, acting as a cosmic time capsule from an era when the universe was forming its heaviest elements.
This stunning Hubble image shows the globular cluster NGC 6426, located approximately 67,000 light-years away in the constellation Ophiuchus. Credit: NASA / ESA / A. Dotter, Dartmouth College / Gladys Kober, NASA and The Catholic University of America.
The NGC 6426 globular cluster, also known as C 1742+031 or GCl 76, was discovered by German-British astronomer William Herschel on June 3, 1786. It is situated about 67,000 light-years away at the equator of the constellation Ophiuchus.
Estimated to be around 13 billion years old, NGC 6426 formed just a few hundred million years after the Big Bang, preserving vital records of the young universe’s conditions. The estimated age of the universe is approximately 13.8 billion years, making this cluster one of the oldest known.
Rather than orbiting within the Milky Way’s disk, NGC 6426 traverses the sparse, spherical outer halo of our galaxy.
While globular clusters were previously thought to consist solely of stars born from a single event, high-resolution spectroscopy indicates that NGC 6426 may exhibit two distinct stellar generations.
According to Hubble astronomers, “NGC 6426 is a collection of stars bound by gravity and is one of the 150 known globular clusters in the Milky Way.” They explained that “these clusters are believed to have formed simultaneously from the same collapsing gas cloud, resulting in stars with similar ages. Older stars are characteristic of globular clusters.”
“At about 13 billion years old, NGC 6426 stands as one of the oldest globular clusters in our galaxy, making it nearly as ancient as the universe itself.”
Astronomers utilized the Hubble Space Telescope to capture this image of NGC 6426 as part of an ongoing study focused on globular star clusters in the Milky Way’s halo.
In this image, blue hues represent shorter wavelengths of visible light, while red hues signify longer wavelengths and some near-infrared light. The colors are carefully selected through standard image processing techniques to accurately depict the wavelengths of light captured by the filters used in the observations.
There is a direct correlation between a star’s color and its temperature; thus, the blue stars visible in this image are hotter than the cooler red stars.
Stars in NGC 6426 are characterized by low metallicity, signifying a lower abundance of elements heavier than hydrogen and helium. These conditions mirror those present in the early universe, where matter primarily consisted of helium and hydrogen, with heavier elements beginning to emerge through nuclear fusion in massive stars.
Source: www.sci.news
