Webb’s First Deep Field (MIRI and NIRCam Images Side by Side)

 Webb’s First Deep Field (MIRI and NIRCam Images Side by Side)

Galaxy cluster SMACS 0723 is a technicolor landscape when viewed in mid-infrared light by NASA’s James Webb Space Telescope. Compared to Webb’s near-infrared image at right, the galaxies and stars are awash in new colors.

Start by comparing the largest bright blue star. At right, it has very long diffraction spikes, but in mid-infrared at left, its smaller points appear more like a snowflake’s. Find more stars by looking for these telltale – if tiny – spikes. Stars also appear yellow, sometimes with green diffraction spikes.

If an object is blue and lacks spikes, it’s a galaxy. These galaxies contain stars, but very little dust. This means that their stars are older – there is less gas and dust available to condense to form new stars. It also means their stars are aging.

The red objects in this field are enshrouded in thick layers of dust, and may very well be distant galaxies. Some may be stars, but research is needed to fully identify each object in the mid-infrared image.

The prominent arcs at the center of the galaxy cluster, which are galaxies that are stretched and magnified by gravitational lensing, appear blue in the Mid-Infrared Instrument (MIRI) image at left and orange in the Near-Infrared Camera (NIRCam) image at right. These galaxies are older and have much less dust.

Galaxies’ sizes in both images offer clues as to how distant they may be – the smaller the object, the more distant it is. In mid-infrared light, galaxies that are closer appear whiter.

Among this kaleidoscope of colors in the MIRI image, green is the most tantalizing. Green indicates a galaxy’s dust includes a mix of hydrocarbons and other chemical compounds.

The differences in Webb’s images are owed to the technical capabilities of the MIRI and NIRCam instruments. MIRI captures mid-infrared light, which highlights where the dust is. Dust is a major ingredient for star formation. Stars are brighter at shorter wavelengths, which is why they appear with prominent diffraction spikes in the NIRCam image.

With Webb’s mid-infrared data, researchers will soon be able to add much more precise calculations of dust quantities in stars and galaxies to their models, and begin to more clearly understand how galaxies at any distance form and change over time.

For a full array of Webb’s first images and spectra, including downloadable files, please visit: https://webbtelescope.org/news/first-images 

NIRCam was built by a team at the University of Arizona and Lockheed Martin’s Advanced Technology Center.

MIRI was contributed by ESA and NASA, with the instrument designed and built by a consortium of nationally funded European Institutes (The MIRI European Consortium) in partnership with JPL and the University of Arizona.




About The Object
Object Name SMACS 0723-73 (1RXS J072319.7-732735, SMACSJ0723.3-7327)
Object Description Lensing Galaxy Cluster
R.A. Position 07:23:19.5
Dec. Position -73:27:15.6
Constellation Volans
Distance Redshift of cluster is z=0.39 (about 4.24 billion light-years)
Dimensions Image is about 2.4 arcmin across
About The Data
Data Description This image was created with Webb data from proposal . It is part of Webb Early Release Observations. The Early Release Observations and associated materials were developed, executed, and compiled by the ERO production team: Jaclyn Barrientes, Claire Blome, Hannah Braun, Matthew Brown, Margaret Carruthers, Dan Coe, Joseph DePasquale, Nestor Espinoza, Macarena Garcia Marin, Karl Gordon, Alaina Henry, Leah Hustak, Andi James, Ann Jenkins, Anton Koekemoer, Stephanie LaMassa, David Law, Alexandra Lockwood, Amaya Moro-Martin, Susan Mullally, Alyssa Pagan, Dani Player, Klaus Pontoppidan, Charles Proffitt, Christine Pulliam, Leah Ramsay, Swara Ravindranath, Neill Reid, Massimo Robberto, Elena Sabbi, Leonardo Ubeda.  The EROs were also made possible by the foundational efforts and support from the JWST instruments, STScI planning and scheduling, Data Management teams, and Office of Public Outreach.
Instrument MIRI, NIRCam
Exposure Dates MIRI: 13 June 2022; NIRCam: 7 June 2022
Filters MIRI>F770W, F1130W, F1280W, F1800W NIRCam>F090W, F150W, F200W, F277W, F356W, F444W
About The Image
Color Info These images are a composite of separate exposures acquired by the James Webb Space Telescope using the MIRI and NIRCam instruments. Several filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are:   MIRI:
Red: F1280W + F1800W Green: F1130W Blue: F770W NIRCam: Red: F444W Orange: F356W Green: F200W +F277W Blue: F090W + F150W
Compass Image This frame is split down the middle. Webb’s mid-infrared image is shown at left, and Webb’s near-infrared image on the right. The mid-infrared image appears much darker, with many fewer points of light. Stars have very short diffraction spikes. Galaxies and stars also appear in a range of colors, including blue, green, yellow, and red. The near-infrared image appears busier, with many more points of light. Thousands of galaxies and stars appear all across the view. They are sharper and more distinct than what is seen in the mid-infrared view. Some galaxies are shades of orange, while others are white. Most stars appear blue with long diffraction spikes, forming an eight-pointed star shapes. There are also many thin, long, orange arcs that curve around the center of the image. Please reference the extended text description for more details.
About The Object
Object Name A name or catalog number that astronomers use to identify an astronomical object.
Object Description The type of astronomical object.
R.A. Position Right ascension – analogous to longitude – is one component of an object's position.
Dec. Position Declination – analogous to latitude – is one component of an object's position.
Constellation One of 88 recognized regions of the celestial sphere in which the object appears.
Distance The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs.
Dimensions The physical size of the object or the apparent angle it subtends on the sky.
About The Data
Data Description
  • Proposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
  • Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.
Instrument The science instrument used to produce the data.
Exposure Dates The date(s) that the telescope made its observations and the total exposure time.
Filters The camera filters that were used in the science observations.
About The Image
Image Credit The primary individuals and institutions responsible for the content.
Publication Date The date and time the release content became public.
Color Info A brief description of the methods used to convert telescope data into the color image being presented.
Orientation The rotation of the image on the sky with respect to the north pole of the celestial sphere.