A group of young stars has been caught loitering near the center of the Milky Way galaxy, a region previously thought to be dominated by a more mature population. Astronomers say the stars form a disk (previously unknown to scientists) that passes through the outer part of the dusty, peanut-shaped bulge at the galactic center.
The thick forest of dust located at the Milky Way’s galactic center is a place where even the bright flame of a burning star can be nearly impossible for astronomers to see. But scientists are coming up with new ways to pull back the veil on this shadowy region, and now, new observations using the VISTA telescope have identified this previously undiscovered group of youngsters. Check out this video on Space.com to see where the stars are located relative to Earth and the sun.
The entire group of young stars has not been seen directly, but its presence is deduced by the detection of a group of very bright, very unusual stars called Cepheids. These act as though they’re attached to a cosmic dimmer switch; they go through regular swings in their apparent brightness over days or months.
Cepheids are a type of variable star, meaning (just as the name suggests) they change over time. They go through regular oscillations in size and temperature, which cause each star to appear as if it were pulsing, going from a peak brightness to a peak dimness, and back again.
These pulsation periods are extremely regular, and in 1908 the astronomer Henrietta Swann Leavitt discovered that brighter Cepheids had longer pulsation periods, and dimmer Cepheids had shorter periods. With this insight, scientists were able to figure out the actual luminosity of these stars (whereas normally scientists only know how bright the star looks from Earth). That information then made it possible to use Cepheids to measure cosmic distances, making these stars an invaluable cosmic tool.
A co-author on the new paper, Daniel Majaess of Saint Mary’s University in Nova Scotia, Canada, said in an email, “I couldn’t help think how amazed Henrietta Leavitt would be to learn about the important and diverse role Cepheids would play in shaping our understanding of the cosmos, all of which is invariably tied to her seminal discovery of the Cepheid period-luminosity relationship. From helping define the extragalactic distance scale and expansion rate of the universe, to now-seminal constraints on the nature of the mysterious region encompassing the galactic center.”
In the new study, a group of scientists report finding 655 new candidate Cepheid stars in the Milky Way. The data comes from the Vista Variables in the Vía Láctea Survey (VVV), completed by the European Southern Observatory’s VISTA telescope at the Paranal Observatory in Chile between 2010 and 2014. Cepheids are brighter than most nonvariable stars — several thousand times brighter than Earth’s sun, for example — which makes these stars easier to spot, said Istvan Dekany of the Pontifical Catholic University of Chile.
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SOURCE: Space.com. Calla Cofield