Jump to content

Webb's First Deep Field: Difference between revisions

Coordinates: Sky map 07h 23m 19.5s, −73° 27′ 15.6″
From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
→Diffraction spikes in the photo: There is really no "inner rim" and "outer rim". There are 18 rims since the mirror is composed of 18 units. All 18 units diffract !!
Line 24: Line 24:
[[File:JWST_diffraction_spikes.svg|thumb|The six diffraction spikes from the rim along with the two horizontal diffraction spikes from the struts, for a total of eight diffraction spikes]]
[[File:JWST_diffraction_spikes.svg|thumb|The six diffraction spikes from the rim along with the two horizontal diffraction spikes from the struts, for a total of eight diffraction spikes]]


The feature in the photo of six bright spikes surrounding each bright light source is a result of [[diffraction]] from the mirror's edges. The mirror's inner edge is a [[Hexagon#Regular_hexagon|regular hexagon]], and the outer edge is a rough hexagon (per figure on right, the exact shape of the outer rim is a 30-sided polygon such that every outer rim edge is parallel to an edge on the inner rim). A telescope typically has a mirror/lens whose rim has a circular shape. Diffraction from circular rims creates circular rings around the light source (as shown in figure on left). The hexagonal inner and outer rims of the Webb telescope's mirror give rise to the six spikes instead of rings of light.<ref>{{cite web|title=Wondering About the 6 Rays Coming out of JWST's Test Image? Here's why They Happen|date=March 19, 2022|url=https://www.universetoday.com/155062/wondering-about-the-6-rays-coming-out-of-jwsts-test-image-heres-why-they-happen/|publisher=[[Universe Today]]|first=Matt|last=Williams|access-date=15 July 2022|archive-date=16 July 2022|archive-url=https://web.archive.org/web/20220716023452/https://www.universetoday.com/155062/wondering-about-the-6-rays-coming-out-of-jwsts-test-image-heres-why-they-happen/|url-status=live}}</ref>
The feature in the photo of six bright spikes surrounding each bright light source is a result of [[diffraction]] from the mirror's edges. The mirror is composed of 18 individual units, each one having the shape of a [[Hexagon#Regular_hexagon|regular hexagon]]. A telescope typically has a mirror/lens whose rim has a circular shape. Diffraction from circular rims creates circular rings around the light source (as shown in figure on left). The hexagonal rim of each unit that together make up the Webb telescope's large mirror give rise to the six spikes instead of rings of light.<ref>{{cite web|title=Wondering About the 6 Rays Coming out of JWST's Test Image? Here's why They Happen|date=March 19, 2022|url=https://www.universetoday.com/155062/wondering-about-the-6-rays-coming-out-of-jwsts-test-image-heres-why-they-happen/|publisher=[[Universe Today]]|first=Matt|last=Williams|access-date=15 July 2022|archive-date=16 July 2022|archive-url=https://web.archive.org/web/20220716023452/https://www.universetoday.com/155062/wondering-about-the-6-rays-coming-out-of-jwsts-test-image-heres-why-they-happen/|url-status=live}}</ref>


Diffraction from the struts holding the secondary mirror creates six additional spikes, but the spikes due to the struts are much less pronounced than the spikes due to the rim. Four of the spikes created by diffraction from the struts are designed to co-align with the spikes created from the diffraction caused by the rim. This leaves one strut, which creates the two horizontal spikes in the photo. The two horizontal spikes due to the one strut are much less pronounced than the six spikes due to the rim.<ref>{{cite web|url= https://webbtelescope.org/contents/media/images/01G529MX46J7AFK61GAMSHKSSN|title=Webb’s Diffraction Spikes}}</ref> See figure on right for a diagram of the eight diffraction spikes.
Diffraction from the struts holding the secondary mirror creates six additional spikes, but the spikes due to the struts are much less pronounced than the spikes due to the rim. Four of the spikes created by diffraction from the struts are designed to co-align with the spikes created from the diffraction caused by the rim. This leaves one strut, which creates the two horizontal spikes in the photo. The two horizontal spikes due to the one strut are much less pronounced than the six spikes due to the rim.<ref>{{cite web|url= https://webbtelescope.org/contents/media/images/01G529MX46J7AFK61GAMSHKSSN|title=Webb’s Diffraction Spikes}}</ref> See figure on right for a diagram of the eight diffraction spikes.

Revision as of 14:14, 19 July 2022

The background of space is black. Thousands of galaxies appear all across the view. Their shapes and colors vary. Some are various shades of orange, others are white. Most stars appear blue, and are sometimes as large as more distant galaxies that appear next to them. A very bright star is just above and left of center. It has eight long, bright-blue diffraction spikes. Between 4 o'clock and 6 o'clock in its spikes are several very bright galaxies. A group of three are in the middle, and two are closer to 4 o'clock. These galaxies are part of the galaxy cluster SMACS 0723, and they are warping the appearances of galaxies seen around them. Long orange arcs appear at left and right toward the center.
Webb's First Deep Field

Webb's First Deep Field is the first operational image taken by the James Webb Space Telescope. The deep-field photograph, covering a tiny area of sky visible from the Southern Hemisphere, is centered on SMACS 0723, a galaxy cluster 4.6 billion light-years from Earth in the constellation of Volans. Thousands of galaxies are visible in the image, some as old as 13 billion years.[1] The image is the highest-resolution image of the early universe ever taken. Captured by the telescope's Near-Infrared Camera (NIRCam), the image was revealed to the public by NASA on 11 July 2022.

Background

The James Webb Space Telescope is a space telescope operated by NASA and designed primarily to conduct infrared astronomy. Launched in December 2021, the spacecraft has been in a halo orbit around the second Sun–Earth Lagrange point (L2), about 1.5 million kilometres (900,000 mi) from Earth, since January 2022. At L2, the gravitational pull of the Sun equals the gravitational pull of the Earth, and the relative directions of the Earth and Sun, as seen from that point, remain constant.[2]

Webb's First Deep Field was taken by the telescope's Near-Infrared Camera (NIRCam) and is a composite produced from images at different wavelengths, totaling 12.5 hours of exposure time.[3][4] The photo achieved depths at infrared wavelengths beyond the Hubble Space Telescope's deepest fields, which took weeks[clarification needed].

SMACS 0723 is a galaxy cluster visible from Earth's Southern Hemisphere,[5] and has often been examined by Hubble and other telescopes in search of the deep past.[2]

Scientific results

The image shows the galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago,[4] covering an area of sky with an angular size approximately equal to a grain of sand held at arm's length.[3] Many of the objects in the image have undergone notable redshift due to the expansion of space over the extreme distance traveled by the light radiating from them.[6]

The combined mass of the galaxy cluster acts as a gravitational lens, magnifying and distorting the images of much more distant galaxies behind it. Webb's NIRCam brought the distant galaxies into sharp focus, revealing tiny, faint structures that had never been seen before, including star clusters and diffuse features.[3]

Diffraction spikes in the photo

Further information: Diffraction spikes
The Webb telescope's mirror outer rim is a rough hexagon, rather than the typical round rim.
A diffraction pattern from a circular aperture has the signature of concentric rings.
The six diffraction spikes from the rim along with the two horizontal diffraction spikes from the struts, for a total of eight diffraction spikes

The feature in the photo of six bright spikes surrounding each bright light source is a result of diffraction from the mirror's edges. The mirror is composed of 18 individual units, each one having the shape of a regular hexagon. A telescope typically has a mirror/lens whose rim has a circular shape. Diffraction from circular rims creates circular rings around the light source (as shown in figure on left). The hexagonal rim of each unit that together make up the Webb telescope's large mirror give rise to the six spikes instead of rings of light.[7]

Diffraction from the struts holding the secondary mirror creates six additional spikes, but the spikes due to the struts are much less pronounced than the spikes due to the rim. Four of the spikes created by diffraction from the struts are designed to co-align with the spikes created from the diffraction caused by the rim. This leaves one strut, which creates the two horizontal spikes in the photo. The two horizontal spikes due to the one strut are much less pronounced than the six spikes due to the rim.[8] See figure on right for a diagram of the eight diffraction spikes.

Significance

Webb's First Deep Field is the first full false-color image from the JWST,[9] and the highest-resolution infrared view of the universe yet captured. The image reveals thousands of galaxies in a tiny sliver of the universe, with Webb's sharp near-infrared view bringing out faint structures in extremely distant galaxies, offering the most detailed view of the early universe to date. Thousands of galaxies, which include the faintest objects ever observed in the infrared, have appeared in Webb's view for the first time.[10][3]

It was first revealed to the public during an event on 11 July 2022 by U.S. president Joe Biden.[2]

Comparison with the Hubble Space Telescope

Deep Field – Galaxy cluster SMACS J0723.3-7327.[11][12][13][14][15][16]
Left: image taken by the Hubble Space Telescope in 2017
Right: same image taken by the James Webb Space Telescope in 2022[17]

See also

References

  1. ^ "Webb's First Deep Field (NIRSpec MSA Emission Spectra)". WebbTelescope.org. Retrieved 14 July 2022.
  2. ^ a b c Overbye, Dennis; Chang, Kenneth; Tankersley, Jim (11 July 2022). "Biden and NASA Share First Webb Space Telescope Image". The New York Times. ISSN 0362-4331. Archived from the original on 12 July 2022. Retrieved 12 July 2022.
  3. ^ a b c d Garner, Rob (11 July 2022). "NASA's Webb Delivers Deepest Infrared Image of Universe Yet". NASA. Archived from the original on 11 July 2022. Retrieved 11 July 2022.
  4. ^ a b "Webb's first deep field". European Space Agency. 12 July 2022. Archived from the original on 12 July 2022. Retrieved 11 July 2022.
  5. ^ "SRELICS". IRAS. Archived from the original on 12 July 2022. Retrieved 12 July 2022.
  6. ^ Isaacs-Thomas, Isabella (11 July 2022). "Here's the deepest, clearest infrared image of the universe ever produced". PBS. Archived from the original on 12 July 2022. Retrieved 12 July 2022.
  7. ^ Williams, Matt (19 March 2022). "Wondering About the 6 Rays Coming out of JWST's Test Image? Here's why They Happen". Universe Today. Archived from the original on 16 July 2022. Retrieved 15 July 2022.
  8. ^ "Webb's Diffraction Spikes".
  9. ^ Strickland, Ashley (11 July 2022). "President Biden reveals the James Webb Space Telescope's stunning first image". CNN. Archived from the original on 12 July 2022. Retrieved 12 July 2022.
  10. ^ Chow, Denise (11 July 2022). "The Webb telescope's first full-color photo is here – and it's stunning". NBC News. Archived from the original on 12 July 2022. Retrieved 11 July 2022.
  11. ^ Garner, Rob (11 July 2022). "NASA's Webb Delivers Deepest Infrared Image of Universe Yet". NASA. Archived from the original on 12 July 2022. Retrieved 12 July 2022.
  12. ^ Overbye, Dennis; Chang, Kenneth; Tankersley, Jim (11 July 2022). "Biden and NASA Share First Webb Space Telescope Image – From the White House on Monday, humanity got its first glimpse of what the observatory in space has been seeing: a cluster of early galaxies". The New York Times. Archived from the original on 12 July 2022. Retrieved 12 July 2022.
  13. ^ Pacucci, Fabio (15 July 2022). "How Taking Pictures of 'Nothing' Changed Astronomy - Deep-field images of "empty" regions of the sky from Webb and other space telescopes are revealing more of the universe than we ever thought possible". Scientific American. Retrieved 16 July 2022.
  14. ^ Deliso, Meredith; Longo, Meredith; Rothenberg, Nicolas (14 July 2022). "Hubble vs. James Webb telescope images: See the difference". ABC News. Retrieved 15 July 2022.
  15. ^ Kooser, Amanda (13 July 2012). "Hubble and James Webb Space Telescope Images Compared: See the Difference - The James Webb Space Telescope builds on Hubble's legacy with stunning new views of the cosmos". CNET. Retrieved 16 July 2022.
  16. ^ Atkinson, Nancy (2 May 2022). "Now, We can Finally Compare Webb to Other Infrared Observatories". Universe Today. Archived from the original on 10 May 2022. Retrieved 12 May 2022.
  17. ^ Chow, Denise; Wu, Jiachuan (12 July 2022). "Photos: How pictures from the Webb telescope compare to Hubble's - NASA's $10 billion telescope peers deeper into space than ever, revealing previously undetectable details in the cosmos". NBC News. Retrieved 16 July 2022.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Webb%27s_First_Deep_Field&oldid=1099201522"