NASA has released a stunning image snapped by the NASA/ESA/CSA James Webb Space Telescope of IC 1623, an ongoing cosmic collision between two irregular galaxies.
IC 1623 is approaching the final stage of its merger, when a violent central inflow of gas will trigger intense starburst activity that could boost the infrared luminosity above the ultraluminous threshold. Image credit: NASA / ESA / CSA / Webb / L. Armus / A. Evans / R. Colombari.
IC 1623 is located approximately 274 million light-years away in the constellation of Cetus.
The galaxy pair was discovered on November 19, 1897 by the American astronomer Lewis Swift.
Also known as Arp 236, ESO 541-23 and IRAS 01053-1746, it consists of two irregular galaxies: IC 1623A and IC 1623B.
IC 1623 is very bright when observed in the infrared and has long been of interest to astronomers.
One of the two galaxies, the infrared-bright, but optically obscured galaxy IC 1623B, has a substantial amount of warm and dense gas. Warm and dense gas is also found in the overlap region connecting the two nuclei.
“IC 1623 is a prime target for Early Science observations with Webb,” said University of Virginia’s Professor Aaron Evans and colleagues.
“It is a striking example of how dust obscuration can hide the true nature of a luminous galaxy and cause a drastic transformation in appearance from the ultraviolet through the infrared.”
“IC 1623 is a mid-stage merger in the Great Observatories all Sky LIRG Survey (GOALS) consisting of two nuclei separated by 26,100 light-years.”
“IC 1623A is bright in ultraviolet and optical light and hosts a large number of optically-luminous young star clusters.”
“IC 1623B is invisible at ultraviolet wavelengths and has prominent dust lanes which cover much of the diffuse light of the underlying stellar population at optical wavelengths.”
In their study, the authors captured IC 1623 across the infrared portions of the electromagnetic spectrum using a trio of Webb’s cutting-edge scientific instruments: MIRI, NIRSpec, and NIRCam.
In so doing, they provided an abundance of data that will allow the astronomical community at large to fully explore how Webb’s unprecedented capabilities will help to unravel the complex interactions in galactic ecosystems.
“The ongoing, extreme starburst causes intense infrared emission, and the merging galaxies may well be in the process of forming a supermassive black hole,” the astronomers explained.
“A thick band of dust has blocked these valuable insights from the view of telescopes like Hubble.”
“However, Webb’s infrared sensitivity and its impressive resolution at those wavelengths allows it to see past the dust and has resulted in the spectacular image above, a combination of MIRI and NIRCam imagery.”
“The luminous core of the galaxy merger turns out to be both very bright and highly compact, so much so that Webb’s diffraction spikes appear atop the galaxy in this image.”
“The 8-pronged, snowflake-like diffraction spikes are created by the interaction of starlight with the physical structure of the telescope.”
“The spiky quality of Webb’s observations is particularly noticeable in images containing bright stars, such as Webb’s first deep field image.”
The team’s results will be published in the Astrophysical Journal Letters.
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Aaron S. Evans et al. 2022. GOALS-JWST: Hidden Star Formation and Extended PAH Emission in the Luminous Infrared Galaxy VV 114. ApJL, in press; arXiv: 2208.14507
