The subject of this Hubble image is NGC 5474, a dwarf galaxy located 21 million light-years away in the constellation of Ursa Major (The Great Bear). This beautiful image was taken with Hubble’s Advanced Camera for Surveys (ACS).
The term “dwarf galaxy” may sound diminutive, but don’t let that fool you — NGC 5474 contains several billion stars! However, when compared to the Milky Way with its hundreds of billions of stars, NGC 5474 does indeed seem relatively small.
NGC 5474 itself is part of the Messier 101 Group. The brightest galaxy within this group is the well-known spiral Pinwheel Galaxy (also known as Messier 101). This galaxy’s prominent, well-defined arms classify it as a “grand design galaxy,” along with other spirals Messier 81 and Messier 74.
Also within this group are Messier 101’s galactic neighbors. It is possible that gravitational interactions with these companion galaxies have had some influence on providing Messier 101 with its striking shape. Similar interactions with Messier 101 may have caused the distortions visible in NGC 5474.
Both the Messier 101 Group and our own Local Group reside within the Virgo Supercluster, making NGC 5474 something of a neighbor in galactic terms.
Astronomers using NASA’s Hubble Space Telescope have assembled a comprehensive picture of the evolving universe – among the most colorful deep space images ever captured by the 24-year-old telescope.
Researchers say the image, in new study called the Ultraviolet Coverage of the Hubble Ultra Deep Field, provides the missing link in star formation. The Hubble Ultra Deep Field 2014 image is a composite of separate exposures taken in 2003 to 2012 with Hubble’s Advanced Camera for Surveys and Wide Field Camera 3.
This fascinating space wallpaper shows the magnetic field of our Milky Way Galaxy as seen by ESA’s Planck satellite. This image was compiled from the first all-sky observations of polarized light emitted by interstellar dust in the Milky Way. The magnetic field is displayed using a visualization technique called line integral convolution (LIC).
This new Hubble image is centered on NGC 5793, a spiral galaxy over 150 million light-years away in the constellation of Libra. This galaxy has two particularly striking features: a beautiful dust lane and an intensely bright center — much brighter than that of our own galaxy, or indeed those of most spiral galaxies we observe.
NGC 5793 is a Seyfert galaxy. These galaxies have incredibly luminous centers that are thought to be caused by hungry supermassive black holes — black holes that can be billions of times the size of the sun — that pull in and devour gas and dust from their surroundings.
This galaxy is of great interest to astronomers for many reasons. For one, it appears to house objects known as masers. Whereas lasers emit visible light, masers emit microwave radiation. The term “masers” comes from the acronym Microwave Amplification by Stimulated Emission of Radiation. Maser emission is caused by particles that absorb energy from their surroundings and then re-emit this in the microwave part of the spectrum.
Naturally occurring masers, like those observed in NGC 5793, can tell us a lot about their environment; we see these kinds of masers in areas where stars are forming. In NGC 5793 there are also intense mega-masers, which are thousands of times more luminous than the sun.
Credit: NASA, ESA, and E. Perlman (Florida Institute of Technology)
In celebration of the 24th anniversary of the launch of NASA’s Hubble Space Telescope, astronomers have captured infrared-light images of a churning region of star birth 6,400 light-years away.
This colorful Hubble Space Telescope mosaic of a small portion of the Monkey Head Nebula unveils a collection of carved knots of gas and dust silhouetted against glowing gas. The cloud is sculpted by ultraviolet light eating into the cool hydrogen gas.
Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
This esthetic close-up of cosmic clouds and stellar winds features LL Orionis, interacting with the Orion Nebula flow. Adrift in Orion’s stellar nursery and still in its formative years, variable star LL Orionis produces a wind more energetic than the wind from our own middle-aged Sun. As the fast stellar wind runs into slow moving gas a shock front is formed, analogous to the bow wave of a boat moving through water or a plane traveling at supersonic speed.
The small, arcing, graceful structure just above and left of center is LL Ori’s cosmic bow shock, measuring about half a light-year across. The slower gas is flowing away from the Orion Nebula’s hot central star cluster, the Trapezium, located off the upper left corner of the picture. In three dimensions, LL Ori’s wrap-around shock front is shaped like a bowl that appears brightest when viewed along the “bottom” edge. The beautiful picture is part of a large mosaic view of the complex stellar nursery in Orion, filled with a myriad of fluid shapes associated with star formation.
Image Credit: NASA, ESA and the Hubble Heritage Team
This long-exposure Hubble Space Telescope image of massive galaxy cluster Abell 2744 (foreground) is the deepest ever made of any cluster of galaxies. It shows some of the faintest and youngest galaxies ever detected in space.
The immense gravity in Abell 2744 is being used as a lens to warp space and brighten and magnify images of more distant background galaxies. The more distant galaxies appear as they did longer than 12 billion years ago, not long after the big bang.
The Hubble exposure reveals almost 3,000 of these background galaxies interleaved with images of hundreds of foreground galaxies in the cluster. Their images not only appear brighter, but also smeared, stretched and duplicated across the field. Because of the gravitational lensing phenomenon, the background galaxies are magnified to appear as much as 10 to 20 times larger than they would normally appear. Furthermore, the faintest of these highly magnified objects is 10 to 20 times fainter than any galaxy observed previously. Without the boost from gravitational lensing, the many background galaxies would be invisible.
The Hubble exposure will be combined with images from Spitzer and NASA’s Chandra X-ray Observatory to provide new insight into the origin and evolution of galaxies and their accompanying black holes.
How far away is spiral galaxy NGC 4921? Although presently estimated to be about 310 million light years distant, a more precise determination could be coupled with its known recession speed to help humanity better calibrate the expansion rate of the entire visible universe. Toward this goal, several images were taken by the Hubble Space Telescope in order to help identify key stellar distance markers known as Cepheid variable stars. Since NGC 4921 is a member of the Coma Cluster of Galaxies, refining its distance would also allow a better distance determination to one of the largest nearby clusters in the local universe. The magnificent spiral NGC 4921 has been informally dubbed anemic because of its low rate of star formation and low surface brightness. Visible in the above image are, from the center, a bright nucleus, a bright central bar, a prominent ring of dark dust, blue clusters of recently formed stars, several smaller companion galaxies, unrelated galaxies in the far distant universe, and unrelated stars in our Milky Way Galaxy.
Supernovae are intensely bright objects. They are formed when a star reaches the end of its life with a dramatic explosion, expelling most of its material out into space. The subject of this new Hubble image, spiral galaxy NGC 6984, played host to one of these explosions back in 2012, known as SN 2012im. Now, another star has exploded, forming supernova SN 2013ek — visible in this image as the prominent, star-like bright object just slightly above and to the right of the galaxy’s center.
SN 2012im is known as a Type Ic supernova, while the more recent SN 2013ek is a Type Ib. Both of these types are caused by the core collapse of massive stars that have shed — or lost — their outer layers of hydrogen. Type Ic supernovae are thought to have lost more of their outer envelope than Type Ib, including a layer of helium.
The observations that make up this new image were taken on August 19, 2013, and aimed to pinpoint the location of this new explosion more precisely. It is so close to where SN 2012im was spotted that the two events are thought to be linked; the chance of two completely independent supernovae so close together and of the same class exploding within one year of one another is a very unlikely event. It was initially suggested that SN 2013ek may in fact be SN 2012im flaring up again, but further observations support the idea that they are separate supernovae — although they may be closely related in some as-yet-unknown way.