Category Archives: Galaxies

Merging Galaxies

NGC3597

One day our Milky Way will be in the midst of a similar merger, ours with Andromeda.

The ESA description:
The subject of this NASA/ESA Hubble Space Telescope image is known as NGC 3597. It is the product of a collision between two good-sized galaxies, and is slowly evolving to become a giant elliptical galaxy. This type of galaxy has grown more and more common as the Universe has evolved, with initially small galaxies merging and progressively building up into larger galactic structures over time.

NGC 3597 is located approximately 150 million light-years away in the constellation of Crater (The Cup). Astronomers study NGC 3597 to learn more about how elliptical galaxies form — many ellipticals began their lives far earlier in the history of the Universe. Older ellipticals are nicknamed “red and dead” by astronomers because these bloated galaxies are not anymore producing new, bluer, stars in ages, and are thus packed full of old and redder stellar populations.

Before infirmity sets in, some freshly formed elliptical galaxies experience a final flush of youth, as is the case with NGC 3597. Galaxies smashing together pool their available gas and dust, triggering new rounds of star birth. Some of this material ends up in dense pockets initially called proto-globular clusters, dozens of which festoon NGC 3597. These pockets will go on to collapse and form fully-fledged globular clusters, large spheres that orbit the centres of galaxies like satellites, packed tightly full of millions of stars.

Image and caption: ESA/Hubble & NASA

IDCS 1426

galaxycluster
A collaboration of three amazing telescopes: Chandra, Herschel and Spitzer.

10 BILLION light-years distant!

Astronomers have made the most detailed study yet of an extremely massive young galaxy cluster using three of NASA’s Great Observatories. This multi-wavelength image shows this galaxy cluster, called IDCS J1426.5+3508 (IDCS 1426 for short), in X-rays recorded by the Chandra X-ray Observatory in blue, visible light observed by the Hubble Space Telescope in green, and infrared light detected by the Spitzer Space Telescope in red.

This rare galaxy cluster, which is located 10 billion light-years from Earth, is almost as massive as 500 trillion suns. This object has important implications for understanding how such megastructures formed and evolved early in the universe. The light astronomers observed from IDCS 1426 began its journey to Earth when the universe was less than a third of its current age. It is the most massive galaxy cluster detected at such an early time.

First discovered by the Spitzer Space Telescope in 2012, IDCS 1426 was then observed using the Hubble Space Telescope and the Keck Observatory to determine its distance. Observations from the Combined Array for Millimeter-wave Astronomy indicated it was extremely massive. New data from the Chandra X-ray Observatory confirm the galaxy cluster’s mass and show that about 90 percent of this mass is in the form of dark matter — the mysterious substance that has so far been detected only through its gravitational pull on normal matter composed of atoms.

There is a region of bright X-ray emission (seen as blue-white) near the middle of the cluster, but not exactly at the center. The location of this “core” of gas suggests that the cluster may have had a collision or interaction with another massive system of galaxies relatively recently, perhaps within about the last 500 million years. This would cause the core to slosh around like wine in a moving glass and become offset, as it appears to be in the Chandra data. Such a merger would not be surprising, given that astronomers are observing IDCS 1426 when the universe was only 3.8 billion years old. Scientists think that, in order for such an enormous structure to form so rapidly, mergers with smaller clusters would likely play a role in the large cluster’s growth.

In addition, while still extremely hot, the bright core contains cooler gas than its surroundings. This is the most distant galaxy cluster where such a “cool core” of gas has been observed. Astronomers think these cool cores are important in understanding how quickly hot gas cools off in clusters, influencing the rate at which stars are born. This cooling rate could be slowed down by outbursts from a supermassive black hole in the center of the cluster. Apart from the cool core, the hot gas in the cluster is remarkably symmetrical and smooth. This is another piece of evidence that IDCS 1426 formed very rapidly in the early universe.

Astronomers note that, despite the high mass and rapid evolution of this cluster, its existence does not pose a threat to the standard model of cosmology.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

NGC 5195

chandrangc5195

Some of the information coming out of the American Astronomical Society being held this week in Florida.

BTW: the Whirlpool is a very nice telescope target in the northern skies even for smaller scopes.  The galaxy is also known as M-51.  Get coordinates here at SEDS.

Here is the AAS release from NASA:

Astronomers have used NASA’s Chandra X-ray Observatory to discover one of the nearest supermassive black holes to Earth that is currently undergoing powerful outbursts, as described in our latest press release. This galactic burping was found in the Messier 51 galaxy, which is located about 26 million light years from Earth and contains a large spiral galaxy NGC 5194 (also known by its nickname of the “Whirlpool”), merging with a smaller companion galaxy NGC 5195.
 The main panel of this graphic shows M51 in visible light data from the Hubble Space Telescope (red, green, and blue). The box at the top of the image outlines the field of view by Chandra in the latest study, which focuses on the smaller component of M51, NGC 5195.  

The inset to the right shows the details of the Chandra data (blue) of this region. Researchers found a pair of arcs in X-ray emission close to the center of the galaxy, which they interpret as two outbursts from the galaxy’s supermassive black hole (see annotated image for additional information). The authors estimate that it took about one to three million years for the inner arc to reach its current position, and three to six million years for the outer arc. 

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Colliding Galaxies

Hubble captures two galaxies colliding.  Image: Credit: NASA and ESA Acknowledgment: A. Gal-Yam (Weizmann Institute of Science)
Hubble captures two galaxies colliding. Image: Credit: NASA and ESA Acknowledgment: A. Gal-Yam (Weizmann Institute of Science)

This is an amazing image. Hubblesite has a “zoomable” version of this and I’ve been trying to count the smaller more distant galaxies – I’m at 22 other than the two subjects of the image.

This NASA Hubble Space Telescope photo of NGC 7714 presents an especially striking view of the galaxy’s smoke-ring-like structure. The golden loop is made of sun-like stars that have been pulled deep into space, far from the galaxy’s center. The galaxy is located approximately 100 million light-years from Earth in the direction of the constellation Pisces.
The universe is full of such galaxies that are gravitationally stretched and pulled and otherwise distorted in gravitational tug-o’-wars with bypassing galaxies.

The companion galaxy doing the “taffy pulling” in this case, NGC 7715, lies just out of the field of view in this image. A very faint bridge of stars extends to the unseen companion. The close encounter has compressed interstellar gas to trigger bursts of star formation seen in bright blue arcs extending around NGC 7714’s center.

The gravitational disruption of NGC 7714 began between 100 million and 200 million years ago, at the epoch when dinosaurs ruled the Earth.

The image was taken with the Wide Field Camera 3 and the Advanced Camera for Surveys in October 2011.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

A Lenticular Galaxy

The lenticular galaxy NGC  6861 Credit: ESA/Hubble & NASA; acknowledgement: J. Barrington
The lenticular galaxy NGC 6861 Credit: ESA/Hubble & NASA; acknowledgement: J. Barrington

Hubble gives us this spectacular view of NGC 6861. I always thought this was an elliptical galaxy. Not so, it’s a hybrid of sorts between an elliptical and a spiral called a lenticular.

Not viewable here at 45 deg North, it is a southern object.  Too bad, it’s a beauty.  I believe this galaxy is in the order of 31 Mpc distant or a little over 101 million light-years and still it is a magnitude 11 to 12.  Distances are very tough to determine so there is some room for error.

Note: My computer is failing. Should I disappear for a short time you will know why. I think I can keep it going long enough to get a replacement – still one never knows.

From ESA via the NASA site:

The subject of this image is NGC 6861, a galaxy discovered in 1826 by the Scottish astronomer James Dunlop. Almost two centuries later we now know that NGC 6861 is the second brightest member of a group of at least a dozen galaxies called the Telescopium Group — otherwise known as the NGC 6868 Group — in the small constellation of Telescopium (The Telescope).

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DDO 68 An Odd Little Galaxy

A dwarf galaxy DDO68 might not be as young as it seems.  Copyright: NASA, ESA. Acknowledgement: A. Aloisi (Space Telescope Science Institute)
A dwarf galaxy DDO68 might not be as young as it seems. Copyright: NASA, ESA. Acknowledgement: A. Aloisi (Space Telescope Science Institute)

From the ESA’s Hubble page:

Astronomers have studied galactic evolution for decades, gradually improving our knowledge of how galaxies have changed over cosmic history. The NASA/ESA Hubble Space Telescope has played a big part in this, allowing astronomers to see further into the distance, and hence further back in time, than any telescope before it – capturing light that has taken billions of years to reach us.

Looking further into the very distant past to observe younger and younger galaxies is very valuable, but it is not without its problems for astronomers. All newly-born galaxies lie very far away from us and appear very small and faint in the images. On the contrary, all the galaxies near to us appear to be old ones.

DDO 68, captured here by the NASA/ESA Hubble Space Telescope, was one of the best candidates so far discovered for a newly-formed galaxy in our cosmic neighbourhood. The galaxy lies around 39 million light-years away from us; although this distance may seem huge, it is in fact roughly 50 times closer than the usual distances to such galaxies, which are on the order of several billions of light years.

Read the rest at ESA’s Hubble page.

A side note: I thought this dwarf galaxy was actually two galaxies in the process of merging, apparently not?

The Serpent’s Nursery

A star forming cloud in the constellation Serpens.  Image credit: NASA/JPL-Caltech/2MASS
A star forming cloud in the constellation Serpens. Image credit: NASA/JPL-Caltech/2MASS

Serpens is one of the constellations we don’t hear much about but is probably familiar if you done much sky watching.

The alpha star has the interesting name of Unukalhai and is located at RA: 15h 45m 00.274s Dec: +06°22’54.854″ or Alt: +50°46’49.676″ Azim: 158°02’58.733″ if you have a compass. I put small finders chart here with the constellation outlined in blue. The tail points almost due south (time is about midnight local).

NASA’s caption:

Within the swaddling dust of the Serpens Cloud Core, astronomers are studying one of the youngest collections of stars ever seen in our galaxy. This infrared image combines data from NASA’s Spitzer Space Telescope with shorter-wavelength observations from the Two Micron All Sky Survey (2MASS), letting us peer into the clouds of dust wrapped around this stellar nursery.
At a distance of around 750 light-years, these young stars reside within the confines of the constellation Serpens, or the “Serpent.” This collection contains stars of only relatively low to moderate mass, lacking any of the massive and incredibly bright stars found in larger star-forming regions like the Orion nebula. Our sun is a star of moderate mass. Whether it formed in a low-mass stellar region like Serpens, or a high-mass stellar region like Orion, is an ongoing mystery.
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Gravitational Lensing

Yesterday I showed a nice gravitational lensed galaxy, then I thought maybe I could show a video that explains what is going on a little more clearly.

This video fills the bill and it is HD so it looks great full screen too.

Video source

A Graceful Arc

A gravitaional lensed galaxy from Hubble and Hershel. Credit: NASA/STScI; S. Allam and team; and the Master Lens Database, L. A. Moustakas, K. Stewart, et al (2014)
A gravitaional lensed galaxy from Hubble and Hershel. Credit: NASA/STScI; S. Allam and team; and the Master Lens Database, L. A. Moustakas, K. Stewart, et al (2014)

Hubble and Herschel combine to study the galaxy known as S0901 seen here as a arc. The arc is a result of huge gravitational forces from a galaxy or galaxies between us and the galactic arc, gravity so strong light from the more distant S0901 is actually magnified and bent into an arc.

Fascinating stuff! I do wonder if we will ever be able to sort of reverse engineer the arc into some semblance of the actual hidden galaxy.

target=”blank’>More images and the following caption at NASA:

The young galaxy SDSS090122.37+181432.3, also known as S0901, is seen here as the bright arc to the left of the central bright galaxy. The distorted view of S0901 is caused by gravitational lensing, resulting from one or more galaxies that lie between the observer and S0901. Although one effect of lensing is to distort the image, another effect is to magnify the light of the lensed object. This effect was used to enable scientists to study S0901 with Herschel’s Heterodyne Instrument for the Far-Infrared (HIFI).

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