This image from Hubble’s Advanced Camera for Surveys shows a cosmic oddity, dwarf galaxy DDO 68. This ragged collection of stars and gas clouds is our own cosmic neighborhood. It is located about 39 million light-years away in the constellation Leo, the Lion. What makes it odd is that its stars contain very few heavy elements — ones that formed in supernovas at the conclusion of the galaxy’s earlier generation of stars. In this respect, it looks like a very young galaxy, one that would more likely be found in the earlier universe, far away. Even more perplexing is the fact that all the other galaxies in its vicinity don’t share this quality and actually look their ages.
For more information, visit: www.spacetelescope.org/images/heic1421a/
Credit: NASA & ESA;
Acknowledgment: A. Aloisi (Space Telescope Science Institute)
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Hubble's Advanced Camera for Surveys captured this image of dwarf irregular galaxy Holmberg II (also known as Arp 268 and UGC 4305). The galaxy is dominated by huge bubbles of glowing gas, which are sites of ongoing star formation. As high-mass stars form in dense regions of gas and dust they expel strong stellar winds that blow away the surrounding material. The cavities are also blown clear of gas by the shock waves produced in supernovas, the violent explosions that mark the end of the lives of massive stars.
Holmberg II is located about 9.8 million light-years away and is found in the constellation Ursa Major (the Great Bear).
For more information, visit: www.spacetelescope.org/images/heic1114a/
Credit: NASA & ESA
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Tags: Holmberg II Hubble NASA galaxy cosmos space astronomy dwarf galaxy irregular galaxy ESA Hubble Space Telescope Ursa Major Big Bear Big Dipper Arp 268 UGC 4305 star formation
In this Hubble image, the spiral galaxy NGC 4319 (center) and a quasar called Markarian 205 (upper right), appear to be neighbors. In reality, the two objects are separated by time and space.
NGC 4319 is 80 million light-years from Earth. Markarian 205 (Mrk 205) is more than 14 times farther away, residing 1 billion light-years from Earth.
Astronomers used two methods to determine the distances to these objects. First, they measured how their light has been stretched in space due to the universe's expansion. Then they measured how much the ultraviolet light from Mrk 205 dimmed as it passed through the interstellar gas of NGC 4319.
Mrk 205 is a relatively nearby quasar. Quasars, once known only as mysterious point-like objects, are now known to be distant galaxies that have extremely bright cores. These powerhouses of light are probably fueled by massive black holes. With powerful telescopes like Hubble, it is often possible to see the quasar's surrounding halo of faint starlight, as is clearly visible around Mrk 205.
Mrk 205 has a companion, a compact galaxy just below it. The objects appear to be interacting. The compact galaxy may be responsible for the structure in Mrk 205's halo.
For more information, visit: hubblesite.org/image/1244/news_release/2002-23
Credit: NASA and the Hubble Heritage Team (STScI/AURA);
Acknowledgment: R. Knacke (Penn State Erie)
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Two enormous galaxies drift through the cosmic void in this striking Hubble Space Telescope image. The galaxy on the left is a lenticular galaxy named 2MASX J03193743+4137580. The side-on spiral galaxy on the right is more simply named UGC 2665. Both galaxies lie approximately 350 million light-years from Earth, and they both form part of the enormous Perseus galaxy cluster.
The Perseus cluster is one of the biggest objects in the known universe, consisting of thousands of galaxies, only a few of which are visible in this image. The wonderful detail in the image is thanks to Hubble's Wide Field Camera 3's powerful resolution and high sensitivity. Wide Field Camera 3 is sensitive to both visible and infrared light, so those are the wavelengths that are captured in this image.
Credit: ESA/Hubble & NASA, W. Harris
Acknowledgement: L. Shatz
For more information, visit: esahubble.org/images/potw2127a/
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Tags: 2MASX J03193743+4137580 UGC 2665 NASA Hubble ESA Hubble Space Telescope telescope space telescope cosmos universe space cosmic astronomy galaxy galaxies lenticular galaxy spiral galaxy Perseus Galaxy Cluster galaxy cluster
NGC 4639 is a beautiful example of a type of galaxy known as a barred spiral. It lies over 70 million light-years away in the constellation of Virgo and is one of about 1,500 galaxies that make up the Virgo Cluster.
In this image, taken by Hubble’s Wide Field Camera 3, one can clearly see the bar running through the bright, round core of the galaxy. Bars are found in about two-thirds of spiral galaxies and are thought to be a natural phase in their evolution. The galaxy’s spiral arms are sprinkled with bright regions of active star formation. Each of the small, bluish dots is actually several hundred light-years across and contains hundreds or thousands of newly formed stars.
NGC 4639 is classified as a Seyfert galaxy, meaning that it has an active galactic nucleus (AGN) whose radiation is extremely luminous and characterized by X-rays. These features are evidence that a massive black hole exists at its center, radically heating the gas and dust it draws in toward itself. Indeed, most galaxies are thought to contain a massive black hole at their centers. The core of NGC 4639 is, relatively speaking, an example of a weak AGN. In contrast, distant galaxies that contain quasars can have their light completely dominated by emissions from their AGN.
For more information, visit: www.spacetelescope.org/images/potw1541a/
Credit: ESA/Hubble & NASA
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Tags: NGC 4639 Hubble NASA galaxy cosmos space astronomy ESA Hubble Space Telescope barred spiral galaxy Active Galactic Nucleus Sefert galaxy AGN black hole