After the first images released via Twitter by the American president Joe Biden, NASA showed five images made by the James Webb Space Telescope this afternoon. This image shows the Stephan’s Quinteta group of five galaxies discovered by the French astronomer Edouard Stephan in the 1877.
These are galaxies approximately distant 300 million light years from Earth, moving under the force of gravity. In particular, the two closest in the central part of the image are merging into a single galaxy. Images with such high resolution will allow scientists to better understand the formation path of new galaxies. The image is a combination of near and mid-infrared spectra, which allow us to see the processes of formation of new stars in unprecedented detail.
The galaxy uppermost in the image, called NGC 7319hosts a black hole with a mass equal to 24 million times that of the Sun. The black hole is obviously not visible, but it is possible to see the light emitted by the materials that are precipitating towards it, capable of emitting light energy evuialent to 40 billions of times that emitted by the Sun.
A further element of interest is linked to the fact that the James Webb is able to provide new images of these galaxies every five days. That is, to frequently provide scientists with new data to work on.
The James Webb Space Telescope is the result of a collaboration between European, US and Canadian space agencies. It was launched into orbit on Christmas Day 2021 from space port of Korou, in French Guiana. Considered the successor of the Hubble telescope, it orbits the Sun at a distance of 1.5 million of kilometers from Earth.
This telescope operates in the infrared frequency, so as to be able to observe even the most distant objects, the light coming from which comes with reduced frequencies, precisely shifted into the infrared. There are four instruments with which it is equipped: the near infrared camera NirCamthe near infrared spectrograph NirSpecthe spectrograph-imager for the near infrared NirIss and the spectrograph-imager for the mid infrared Miri.
NirCam will be used for almost all aspects of the Webb telescope’s activity, from studying deep fields to galaxies, from star-forming regions to planets in our solar system. This, like the other instruments, use spectroscopy, that is, they break down the light spectrum of the objects that are observed by the telescope.
Thanks to a system of micro shutters, about 250 thousand are installed, instead NirSpec allows you to observe up to 100 light sources simultaneously, eliminating the background light which reduces the sensitivity of the result. Furthermore, NirSpec is able to build time series of luminous objects or, for example, to follow an exoplanet along its entire orbit to map its temperature.
Niris will allow you to observe the planets that orbit some of the brightest nearby stars, blurring the image of the latter and spreading the light on many pixels to avoid saturating the detectors and allowing you to observe these planets. However, this device also includes a non-slit spectroscopy mode optimized for the pure search for active galaxies, that is, galaxies that form unknown stars.
Miri will focus on mid-infrared wavelengths (between 5 and 27 microns) and show, for example, the distributions of dust and cold gas in star-forming regions in our own and other galaxies. Low resolution spectroscopy (5-12 microns) will allow us to study the surface of objects, to determine their composition. While its coronagraphic imaging function will allow it to detect exoplanets and study the dust disks around their host stars.
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