Webb spectroscopy in the mid-infrared region will reveal molecules and elements

(ORDO NEWS) — This week, the first data on MIRI’s medium-resolution spectroscopy mode and spectroscopic engineering were obtained.

Two members of the MIRI commissioning team – David Low of the Space Telescope Science Institute and Alvaro Labiano of the Center for Astrobiology – explain this mode as follows:

“One of the most difficult modes of operation of the Webb instrument is the mode of operation of the MIRI Medium Resolution Spectrometer (MRS).

MRS is an integral field spectrograph that provides spectral and spatial information simultaneously for the entire field of view. It forms three-dimensional “data cubes” in which each pixel of the image contains a unique spectrum.

Such equipment is an extremely powerful tool for studying the composition and kinematics of astronomical objects, as they combine the advantages of both conventional imaging and spectroscopy.

The MRS is designed so that its spectral resolution (observed wavelength divided by the smallest discernible wavelength difference) is about 3,000.

This is high enough to understand the key atomic and molecular features of various media. At the highest redshifts, the MRS will be able to study the hydrogen emission from the first galaxies.

It is able to detect bright spectral fingerprints of elements such as oxygen, argon and neon, which can tell us about the properties of ionized gas in the interstellar medium.

In addition, MRS will map the spectral features of water ice and simple organic molecules on giant planets in our solar system and in planet-forming disks around other stars.

To maximize coverage of the wide wavelength range from 5 to 28 microns, the MRS integrated field units are broken down into twelve separate wavelength ranges, each of which must be individually calibrated.

The first results of testing this alignment process, obtained in each of the twelve ranges, can be seen on the example of observations of the bright giant star HD 37122, located near the Large Magellanic Cloud.

Once the spatial alignment and image quality across multiple bands are well characterized, the MIRI team will first focus on calibrating the instrument’s spectroscopic response.”


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