File:Caldwell 42.jpg
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Summary
DescriptionCaldwell 42.jpg |
English: Caldwell 42, also known as NGC 7006, is one of 18 globular clusters in the Caldwell catalog. If you look at this Hubble image of the cluster closely, you may be able to spot several tiny background galaxies (which appear fuzzier and more extended than the cluster’s stars). Each of those distant island universes likely contains a hundred or more globular clusters of its own. Unlike open star clusters, which are smaller and more loosely bound, globular clusters are densely packed with hundreds of thousands of stars held in a roughly spherical shape by their mutual gravity.
Globular clusters like Caldwell 42 are relics of the galaxy’s earliest years. Since they were born as the nascent galaxy was forming, these clusters provide a glimpse backward in time and provide a hint of what the Milky Way was like billions of years ago. Studying globular clusters allows scientists to learn more about how the first stars formed in our galaxy and the role the clusters played in the galaxy’s development. However, Caldwell 42 has a very elongated orbit around the center of our galaxy, which might hint toward an extragalactic origin. It seems that some globular clusters may have once been independent dwarf galaxies that were later absorbed by the Milky Way. The cluster is nestled in the diminutive constellation Delphinus and is best viewed in the late summer in the Northern Hemisphere or late winter in the Southern Hemisphere. It was discovered in 1784 by British astronomer William Herschel — the discoverer of dozens of celestial objects in the Caldwell catalog. Caldwell 42 isn’t terribly bright to begin with compared to other star clusters, so at its distance of about 135,000 light-years from Earth it’s really not the most impressive sight to most amateur astronomers. In a moderate-sized telescope, the magnitude-10.5 cluster appears as a dim, circular smudge. It is difficult to pick out individual stars in the cluster, though large amateur telescopes may be able to resolve a few of the cluster’s most vibrant stellar members. This image, taken by Hubble’s Advanced Camera for Surveys, includes light detected at both visible and infrared wavelengths. When viewed in visible wavelengths alone, Caldwell 42 appears dimmer. This is because intervening dust between us and Caldwell 42 scatters some of the cluster’s visible light but lets the infrared light pass through. Hubble’s multi-wavelength view transforms this otherwise faint smudge into a dazzling spectacle, while helping astronomers analyze the cluster’s stars and investigate Caldwell 42’s history. For more information about Hubble’s observations of Caldwell 42, see: www.spacetelescope.org/images/potw1137a/ Credit: ESA/Hubble & NASA For Hubble's Caldwell catalog site and information on how to find these objects in the night sky, visit: www.nasa.gov/content/goddard/hubble-s-caldwell-catalog |
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Source | https://www.flickr.com/photos/144614754@N02/49200475127/ |
Author | NASA Hubble |
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This image was originally posted to Flickr by NASA Hubble at https://flickr.com/photos/144614754@N02/49200475127 (archive). It was reviewed on 23 February 2020 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
23 February 2020
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Date and time of data generation | 10:00, 12 September 2011 |
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Image title |
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Orientation | Normal |
Horizontal resolution | 72 dpi |
Vertical resolution | 72 dpi |
Software used | Adobe Photoshop CS5 Windows |
File change date and time | 10:51, 15 June 2011 |
Y and C positioning | Centered |
Exif version | 2.31 |
Date and time of digitizing | 10:47, 12 June 2011 |
Meaning of each component |
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Supported Flashpix version | 1 |
Color space | Uncalibrated |
Bits per component |
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Height | 3,851 px |
Width | 3,851 px |
Pixel composition | RGB |
Number of components | 3 |
Contact information |
http://www.spacetelescope.org/ Karl-Schwarzschild-Strasse 2 Garching bei München, , D-85748 Germany |
Publisher | ESA/Hubble |
Keywords | NGC 7006 |
Short title |
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Type of media | Observation |
Credit/Provider | ESA/Hubble&NASA |
Source | ESA/Hubble |
Date metadata was last modified | 12:51, 15 June 2011 |
Unique ID of original document | uuid:2B5D399DB094E011BB7599C223246ECD |
Copyright status | Copyright status not set |
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JPEG file comment | This NASA/ESA Hubble Space Telescope image shows a compact and distant globular star cluster that lies in one of the smallest constellations in the night sky, Delphinus (The Dolphin). Due to its modest size, great distance and relatively low brightness, NGC 7006 is often ignored by amateur astronomers. But even remote globular clusters such as this one appear bright and clear when imaged by Hubble’s Advanced Camera for Surveys. NGC 7006 resides in the outskirts of the Milky Way. It is about 135 000 light-years away, five times the distance between the Sun and the centre of the galaxy, and it is part of the galactic halo. This roughly spherical region of the Milky Way is made up of dark matter, gas and sparsely distributed stellar clusters. Like other remote globular clusters, NGC 7006 provides important clues that help astronomers to understand how stars formed and assembled in the halo. The cluster now pictured by Hubble has a very eccentric orbit indicating that it may have formed independently, in a small galaxy outside our own that was then captured by the Milky Way. Although NGC 7006 is very distant for a Milky Way globular cluster, it is much closer than the many faint galaxies that can be seen in the background of this image. Each of these faint smudges is probably accompanied by many globular clusters similar to NGC 7006 that are too faint to be seen even by Hubble. This image was taken using the Wide Field Channel of the Advanced Camera for Surveys, in a combination of visible and near-infrared light. The field of view is a little over 3 by 3 arcminutes. |