Editor TLN
Dec. 29 () –
The spiral galaxy NGC 7469which hosts an active galactic nucleus, has become the December image of the James Webb telescope. It is a luminous frontal spiral galaxy of approximately 90,000 light years across which is located approximately 220 million light years from Earth in the constellation Pegasus, as reported by the European Space Agency (ESA).
According to ESA, this spiral galaxy has recently been studied as part of the ‘LIRG survey’ The Great Observatories All-Sky Survey (GOALS), whose goal is to study the physics of star formation, black hole growth, and feedback in four merging near-luminous infrared galaxies. Also, other galaxies studied as part of the survey include earlier ‘ESA Webb’ images of the month ‘II ZW 096’ and ‘IC 1623’.
The spiral galaxy hosts an active galactic nucleus (AGN), which is an extremely bright central region dominated by light emitted by dust and gas as it falls into the galaxy’s central black hole. This galaxy provides astronomers with the unique opportunity to study the relationship between AGN and starburst activity because this particular object harbors an AGN that is surrounded by a starburst ring at a distance of just 1,500 light-years.
As the ESA has pointed out, the compact nature of the system and the presence of a large amount of dust have made it difficult for scientists to achieve the resolution and sensitivity necessary to study this relationship in the infrared. However, with Webb, astronomers can explore the galaxy’s starburst ring, the central AGN, and the gas and dust in between.
In addition, using Webb instruments such as ‘MIRI’, ‘NIRCam’ and ‘NIRspec’ to obtain images and spectra of ‘NGC 7469’ in unprecedented detail, the ‘GOALS’ team has discovered a number of details about the object including never-before-seen very young star-forming clusters, as well as pockets of very warm, turbulent molecular gas, and direct evidence for the destruction of small dust grains within a few hundred light-years of the nucleus, demonstrating that the AGN is impacting the surrounding interstellar medium.
Likewise, highly ionized diffuse atomic gas appears to be pouring out of the nucleus at about 4 million miles per hour, part of a galactic flow that had previously been identified from the ground, but is now revealed in detail with Webb.
According to the researchers, a prominent feature of this image is the “striking” six-pointed star that aligns “perfectly” with the heart of NGC 7469. Unlike the galaxy, this is not an actual celestial object, but an imaging artifact known as a diffraction spike, caused by bright, unresolved AGN, they have reported.
Specifically, diffraction spikes are patterns produced when light bends around the sharp edges of a telescope. Webb has three struts, with two angled at 150 degrees from her vertical strut, and its primary mirror is composed of hexagonal segments containing edges for light to be diffracted. Webb struts are designed so that their diffraction peaks partially overlap those created by the mirrors. Both lead to the complex Webb star pattern.
