Euclid has captured a detailed image of the NGC 6397 globular cluster, situated in the Milky Ways disc and consisting of stars that provide insights into the galaxys history. Observing the entire cluster, particularly the faint stars in its external areas, has been an obstacle for existing telescopes. ESAs Gaia mission can track the motion of globular clusters, however cant tell whats going on with extremely faint stars. “If there are no tidal tails, then there could be a dark matter halo around the globular cluster, avoiding the external stars from escaping. We do not expect dark matter haloes around smaller-scale things like globular clusters, just around bigger structures like dwarf galaxies or the Milky Way itself.”.
Euclid has actually caught a thorough image of the NGC 6397 globular cluster, located in the Milky Ways disc and containing stars that use insights into the galaxys history. Observing the whole cluster, particularly the faint stars in its external regions, has been a difficulty for existing telescopes.
Euclids detailed imaging of the NGC 6397 globular cluster may reveal tidal tails and provide new insights into dark matters role in the Milky Way, in addition to the development of one of the galaxys earliest outstanding structures.
Capturing the Sparkle of NGC 6397
This sparkly image shows Euclids view on a globular cluster called NGC 6397. Globular clusters are collections of hundreds of thousands of stars held together by gravity.
Found about 7800 light-years from Earth, NGC 6397 is the second-closest globular cluster to us. Together with other globular clusters it orbits in the disc of the Milky Way, where the bulk of stars are situated.
Revealing the History Through Stars
Globular clusters are a few of the oldest objects in the Universe. Thats why they contain a lot of ideas about the history and evolution of their host galaxies, like this one for the Milky Way.
The obstacle is that it is generally challenging to observe a whole globular cluster in simply one sitting. Their centers consist of lots of stars, numerous that the brightest hush the fainter ones. Their external regions extend a long method out and include mainly low-mass, faint stars. It is the faint stars that can tell us about previous interactions with the Milky Way.
The Unique Capabilities of Euclid
” Currently no other telescope than Euclid can observe the whole globular cluster and at the very same time identify its faint outstanding members in the external areas from other cosmic sources,” explains Euclid Consortium researcher Davide Massari of the National Institute for Astrophysics in Italy.
This ancient stellar fashion jewelry box, a globular cluster called NGC 6397, glitters with the light from hundreds of countless stars. Astronomers utilized the NASA/ESA Hubble Space Telescope to evaluate the clusters distance at 7,800 light-years away. Credit: NASA, ESA, and T. Brown and S. Casertano (STScI), Acknowledgment: NASA, ESA, and J. Anderson (STScI).
For example, the Hubble Space Telescope has actually observed the core of NGC 6397 in information (see image above), however it would take a great deal of observing time with Hubble to map the outskirts of the cluster, something Euclid can do in simply one hour. ESAs Gaia mission can track the motion of globular clusters, but cant inform whats happening with extremely faint stars. And telescopes from the ground can cover a bigger field, but with a poorer depth and resolution, so they cant distinguish the faint outskirts completely.
Searching for Tidal Tails.
Davide and his coworkers will utilize Euclid to search for tidal tails in globular clusters: a tidal tail is a trail of stars that extends far beyond the cluster because of a previous interaction with a galaxy.
This cutout from Euclids full view of NGC 6397 is at the high resolution of the VIS instrument. This is 9 times better than the definition of NISP that was selected for the full view; this was provided for the practical reason of limiting the format of the complete image to a manageable size for downloading. The cutout totally showcases the power of Euclid in getting incredibly sharp images over a large region of the sky in one single pointing. This image represents just a small part of the entire color view, the exact same quality as shown here is offered over the complete field. Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi, CC BY-SA 3.0 IGO.
” We expect all of the globular clusters in the Milky Way to have them, but up until now we have only seen them around just a few,” states Davide. “If there are no tidal tails, then there could be a dark matter halo around the globular cluster, preventing the outer stars from getting away. We do not anticipate dark matter haloes around smaller-scale objects like globular clusters, just around bigger structures like dwarf galaxies or the Milky Way itself.”.
A New Understanding of Stellar Evolution.
If Davide and his group find tidal tails for NGC 6397 and other globular clusters in the Milky Way, that would enable them to extremely exactly determine how the clusters orbit our galaxy. “And this will tell us how dark matter is dispersed in the Milky Way,” Davide includes.
With Euclids observations, the team also desires to identify the age of globular clusters, to investigate the chemical residential or commercial properties of their outstanding populations, and to study ultra-cool dwarf stars– the most affordable mass members of the cluster.
See more of Euclids First Images.
