Hubble Captures Unusual Spiral Galaxy, Complicated Globular Cluster

Sep 21, 2022 | Active Galaxies, Daily Space, Galaxies, Globular Cluster

IMAGE: The galaxy NGC 1961 unfurls its gorgeous spiral arms in this newly released image from NASA’s Hubble Space Telescope. Glittering, blue regions of bright young stars dot the dusty spiral arms winding around the galaxy’s glowing center. CREDIT: NASA, ESA, J. Dalcanton (University of Washington), R. Foley (University of California – Santa Cruz); Image processing: G. Kober (NASA Goddard/Catholic University of America)

Astronomy is an old field. Thanks to centuries of observations astronomers have come up with categories for different types of galaxies. Still, like most of the neat little boxes humans make, some things fall out.

One such object is NGC 1961, which is an intermediate spiral galaxy with an active galactic nucleus. It has spiral arms but lacks the bars of a barred spiral type. Instead, its stars are in a big pile at the center, much brighter than the rest of the galaxy. NGC 1961 likely has a supermassive black hole at its center, which affects the evolution of its population of stars and shape by sending large jets of charged particles into and through the galaxy.

One of the things Hubble was designed to look for was the observation of individual stars in globular clusters as a way to gain insight into the evolution of these systems. Globular clusters at the center of our galaxy have been hard to study because of the large amounts of gas and dust blocking our view. The process of an object dimming to the point of becoming undetectable due to dust or gas is called extinction, and it happens a lot when we look toward the center of the Milky Way.

IMAGE: A glittering multitude of stars in the globular cluster Terzan 4 fills this image from the NASA/ESA Hubble Space Telescope. CREDIT: ESA/Hubble & NASA, R. Cohen

Now, however, combining data from two Hubble instruments and new processing techniques has allowed scientists to un-extinct globular clusters and even determine the age of some of them. One such globular cluster is named Terzan 4. Thanks to the new method, Terzan 4’s age has been determined to within a billion years. Considering an order of magnitude is a good measurement in astronomy, that’s a relatively precise age for this cluster.

For those listening to our podcast, we’ll have the images in our show notes at DailySpace.org.

More Information

NASA image release

NASA image release

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