” Using a technique called transit spectroscopy, the NIRISS instrument can collect a spectrum of an exoplanets atmosphere, which includes various markers that permit astronomers to determine its composition, temperature, potential habitability signatures, and other important attributes.
These simulated images show the galaxy cluster MACS J0416.1-2403 as it might look when observed with NIRISS in WFSS mode. Left: This is a simulation of a direct image of the cluster using just the F115W filter (no dispersion). Galaxies are seen as dots or blobs throughout. Credit: Chris Willott/National Research Council Canada, Herzberg Astronomy and Astrophysics Research Centre.
The dispersed picture of the cluster as seen with the F115W filter and the GR150C grism. Individual spectra appear as the matching galaxy smeared horizontally. Credit: Chris Willott/National Research Council Canada, Herzberg Astronomy and Astrophysics Research Centre.
Individual spectra appear as the corresponding galaxy smeared vertically. One galaxy and its corresponding spectra are circled in blue in the images.
Wide Field Slitless Spectroscopy (WFSS).
” The WFSS mode on NIRISS allows Webb to acquire spectra however for countless things, such as galaxies, at the very same time over the detectors whole field of view (4.84 arcmin2). The spectra of thousands of galaxies will enable measurement of their distances, ages, and other physical parameters to trace how galaxies evolve over the life time of deep space. In the simulated example revealed in the figure, the galaxy cluster acts like a cosmic lens that amplifies and stretches the images of faint background galaxies, so they can be studied in even greater information.
” Since NIRISS can gather so numerous spectra at a time using the WFSS mode, specific spectra can overlap if their sources are too close. There are therefore 2 orthogonal grisms, GR150C and GR150R, that can produce spectra horizontally and vertically, respectively, which helps to disentangle blended spectra from different galaxies.
A prototype of a mask used in the Canadian NIRISS instrument in AMI mode, showing the layout of the 7 hexagonal holes in the mask with regard to the Webb main mirror sectors and secondary mirror supports. Credit: Anand Sivaramakrishnan/Space Telescope Science Institute.
NASAs James Webb Space Telescope is the follower to the Hubble Space Telescope, the most effective infrared science observatory ever to be sent out into area. From its orbit almost a million miles from Earth, Webb will study a few of the most remote things in the universe. Credit: NASA
The Webb Space Telescope group continues to commission the 17 science instrument modes. They just recently asked Nathalie Ouellette of the Université de Montréal to give more detail about the modes of the Near-Infrared Imager and Slitless Spectrograph (NIRISS), Canadas scientific instrument on Webb.
” NIRISS will have the ability to catch both images and spectra from different kinds of celestial objects in near-infrared light, at wavelengths as much as 5.0 microns. The NIRISS team has established four instrument modes to gather various type of data that are appropriate for different targets and clinical goals.
With SOSS mode, the NIRISS instrument will be able to study the environments of exoplanets as they pass in front of their star utilizing a method called transit spectroscopy. The spectrum observed by NIRISS will act like an alien barcode, showing the existence of particular atoms and particles. The above illustration reveals how absorption functions due to salt (Na) and potassium (K) can be seen in the visible light spectrum; Webbs infrared light observations will be sensitive to other features such as water vapor, co2, and methane. Credit: European Southern Observatory
Single Object Slitless Spectroscopy (SOSS).
” The SOSS mode on NIRISS permits the Webb telescope to get high-precision spectra from one bright things at a time. This mode is optimized to bring out time-series observations, which are perfect for studying a phenomenon that alters over the length of an usually hours-long observation, such as an exoplanet transiting in front of its host star.
NASAs James Webb Space Telescope is the follower to the Hubble Space Telescope, the most powerful infrared science observatory ever to be sent out into space. From its orbit almost a million miles from Earth, Webb will study some of the most far-off things in the universe. The above illustration shows how absorption functions due to salt (Na) and potassium (K) can be seen in the noticeable light spectrum; Webbs infrared light observations will be delicate to other features such as water vapor, carbon dioxide, and methane.” The WFSS mode on NIRISS permits Webb to get spectra however for thousands of objects, such as galaxies, at the exact same time over the detectors entire field of view (4.84 arcmin2).” The AMI mode on NIRISS allows Webb to study things that are extremely close together on the sky, using a special strategy called interferometry.
Aperture Masking Interferometry (AMI).
” The AMI mode on NIRISS permits Webb to study objects that are really close together on the sky, utilizing an unique method called interferometry. This enables 2 objects that are close to each other that would otherwise look like a single blurred point, like an exoplanet orbiting a star, to appear as two unique points of light in a Webb image. The AMI mode will be utilized to observe exoplanets, brown dwarfs, and protoplanetary disks.
NIRISS Imaging.
” Because of the importance of near-infrared imaging to Webbs clinical success, NIRISS includes an imaging capability that functions as a backup to NIRCam imaging. This capability can be used in parallel, with NIRCam and NIRISS all at once taking pictures of 2 closely separated fields of view, imaging a bigger area of an extended source.”.
— Nathalie Ouellette, Webb outreach researcher, Université de Montréal.
Composed by Jonathan Gardner, Webb deputy senior project researcher, NASAs Goddard Space Flight.
