New survey of the Milky Way reveals 3.3 billion celestial objects

Astronomers released new images this week of the Milky Way that offer an unprecedented look at a huge slice of the galaxy, complete with star clusters, cosmic dust clouds, and the Sagittarius A* supermassive black hole.

The images released Wednesday, a product of the National Science Foundation’s Dark Energy Camera, which captured two years of data through a telescope at the agency’s observatory in Chile, are the second of their kind to come from the NSF Dark Energy Study. The project is essentially designed to observe and track the expansion of the universe. The survey revealed just over 3.3 billion celestial objects in the galactic plane of the Milky Way, marking the largest catalog yet produced by a single camera.

“This is quite a technical feat. Imagine a group photo of over three billion people and every individual is recognizable!” Debra Fischer, director of NSF’s division of astronomical sciences, said in a statement to the Harvard-Smithsonian Center for Astrophysics. “Astronomers will be poring over this detailed portrait of more than three billion stars in the Milky Way for decades to come. This is a fantastic example of what partnerships between federal agencies can accomplish.”

NSF’s Dark Energy Camera, an instrument attached to the 4-meter Víctor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory in Vicuña, examines the plane of the Milky Way at optical and near-infrared wavelengths from the point of view of the southern sky. It produced more than 10 terabytes of data from 21,400 individual exposures during the last survey of outer space, according to the federal agency.


The instrument’s first data collection was published in 2017. When taken together, the data collected during the first and second rounds of the dark energy survey now represents 6.5% of the night sky, spanning 130 degrees of longitude. said the NSF. This is a gigantic feat, since most objects in the Milky Way exist within the galaxy’s disk, which is seen in the images as the bright band running horizontally through the center, and some of its properties prevent astronomers can see objects clearly. The “large number of stars” also poses challenges for observing efforts, according to the NSF, as they can overlap in the images.

Combining data collected during a 2014 cosmic survey called PS1, which was operated by the Pan-STARRS 1 Science Consortium, with images compiled using the Dark Energy Camera may provide an even broader view of the galaxy, explained Edward Schlafly, AURA researcher. -administered by the Space Telescope Science Institute, in a statement to the NSF.

“When combined with images from Pan-STARRS 1, DECaPS2 [the dark energy camera] completes a 360-degree panoramic view of the Milky Way’s disk, and also reaches for much fainter stars,” said Schlafly, who is also co-author of a paper describing DECaPS2 published in the Astrophysical Journal Supplement. “With this new survey, we can map the three-dimensional structure of the stars and dust of the Milky Way in unprecedented detail.”

Scientists, astronomers, and members of the general public can explore the full Dark Energy Survey dataset, including three-dimensional portraits of the galaxy, using an interactive online interface found here.

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