Record view of space: The Hubble Space Telescope has released the largest near-infrared image of the sky to date. The image shows galaxies and stellar cradles in a section of sky almost six times the size of the full moon, making it possible to detect even rare variants and evolutionary stages of galaxies. The close-up can also help select targets for the new James Webb Space Telescope, which is less wide but can look deeper.
Whether star cradles, exoplanets, galaxies or the portrait of the earliest star to date: For more than 30 years the Hubble Space Telescope has been providing new insights into the cosmos and has brought countless new discoveries to astronomy. While the new James Webb Space Telescope works primarily in the infrared range, Hubble is more of an all-rounder: its spectrum ranges from the ultraviolet to the visible to the near-infrared wavelength range of light.
A patch of sky the size of six full moons
The Hubble telescope has now set a new milestone in the near infrared. Thanks to a new recording technique, astronomers led by Lamiya Mowla from the University of Toronto managed to take the largest near-infrared image ever made by Hubble. The 3D-DASH survey offers, for the first time, a complete, high-resolution, near-infrared survey of the entire COSMOS field, one of the richest datasets for extragalactic studies outside the Milky Way.
3D-DASH covers a total area of 1.35 square degrees in the sky, almost six times the size of the full moon in the sky. Until now, such a large near-infrared image was only available from ground-based telescopes, which, however, provided poorer resolution and thus limited the observation possibilities. According to the astronomers, the current record will probably not be broken by the James Webb telescope either, because it tends to look at smaller sections with greater depth.
New technology enabled record recording
To image such an expansive area of sky, the research team used a new technique called Drift And SHift (DASH). With this, the Hubble telescope can target and record eight sections of the sky during an orbit instead of just one. This allows it to survey an area in high resolution in just 250 hours that previously would have taken the telescope 2,000 hours.
The individual recordings were then combined to form an overall mosaic. “3D-DASH adds a new layer of unique observations to the COSMOS field and is also a stepping stone for the space surveys of the next decade,” says co-author Ivelina Momcheva from the Max Planck Institute for Astronomy in Heidelberg. “It gives us a foretaste of future scientific discoveries and allows us to develop new techniques to analyze these large data sets.”
Rare objects and processes revealed
The new near-infrared image is particularly exciting for astronomy because it shows a large number of galaxies, stellar cradles and other distant objects at once, thus also capturing rare phenomena and processes. These include particularly massive giant galaxies, galaxies shortly before merging or cradles of stars and highly active black holes.
“I’m curious about giant galaxies, the most massive galaxies in the universe, formed by the merger of other galaxies. How did their structures evolve and what changed their shape?” says Mowla. “It was difficult to study these extremely rare events with existing images, and that was the reason for designing this large survey.”
Target finder for the James Webb telescope
3D-DASH can also help astronomers identify rare objects as targets for follow-up observations with the new James Webb Space Telescope. It’s the largest near-infrared image of the sky until the next generation of telescopes, like the Nancy Grace Roman Space Telescope and Euclid, come online in the next decade.
Until then, professional astronomers and amateur stargazers can explore the sky with an online, interactive version of the 3D DASH image. (The Astrophysical Journal, in press; arXiv:2206.01156)
Source: Max Plank Institute for Astronomy
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