Astronomers employing the NASA/ESA Hubble Space Telescope have obtained a stunning image of NGC 6426, an ancient globular star cluster located in the outer halo of the Milky Way galaxy. This remarkable object contains two distinct generations of stars, serving as a cosmic time capsule from an era when the universe was still forming its heaviest elements.
This Hubble image showcases the globular cluster NGC 6426 located about 67,000 light-years away in the constellation Ophiuchus. Image credits: NASA / ESA / A. Dotter, Dartmouth College / Gladys Kober, NASA and The Catholic University of America.
NGC 6426 is situated approximately 67,000 light-years from Earth, at the celestial equator within the constellation Ophiuchus.
This globular cluster, also referred to as C 1742+031 or GCl 76, was discovered by German-British astronomer William Herschel on June 3, 1786.
Estimated to be around 13 billion years old, NGC 6426 formed only a few hundred million years after the Big Bang. Given that the universe is about 13.8 billion years old, this cluster encapsulates evidence of conditions that existed in the early universe.
Unlike many clusters, NGC 6426 traverses the sparse outer halo of the Milky Way rather than orbiting within the galaxy’s disk.
Initially thought to consist solely of contemporaneous stars, advanced high-resolution spectroscopy has revealed that NGC 6426 may harbor two distinct generations of stars.
“NGC 6426 is a collection of globular stars bound by their mutual gravity and ranks among the 150 known globular clusters in the Milky Way,” Hubble astronomers stated.
“These star groups are believed to have formed from the same collapsing gas cloud, often resulting in stars of similar ages. Stars in globular clusters are generally quite old.”
“At approximately 13 billion years old, NGC 6426 ranks as one of the oldest globular clusters in the Milky Way, almost as ancient as the universe itself.”
Astronomers utilized the Hubble Telescope to capture images of NGC 6426 as part of their research on globular star clusters within the Milky Way halo.
“In this image, blue represents shorter wavelengths of visible light, while red signifies longer wavelengths and some near-infrared light,” they explained.
“The colors in Hubble images are processed to accurately depict the wavelengths of light that pass through the sensors used during observations.”
“There exists a direct relationship between a star’s color and its temperature; hence, the blue stars in this image are hotter compared to the cooler red stars.”
The stars in NGC 6426 exhibit low metallicity, indicating a scarcity of elements heavier than hydrogen or helium.
“These conditions mirror those of the early universe, a time when matter predominantly consisted of helium and hydrogen, with heavier elements beginning to emerge through nuclear fusion within massive stars.”
Source: www.sci.news
