1. Tour of M60-UCD1
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Astronomers may have discovered the densest galaxy in the nearby Universe. The galaxy, known as M60-UCD1, is located about 54 million light years from Earth. M60-UCD1 is packed with an extraordinary number of stars and this has led scientists to classify it as an "ultra-compact dwarf galaxy." This means that this galaxy is smaller and has more stars than just a regular dwarf galaxy. While astronomers already knew this, it wasn't until these latest results from Chandra, Hubble and telescopes on the ground that they knew just how dense this galaxy truly is. M60-UCD1 has the mass about 200 million times our Sun and, remarkably, about half of this mass is packed into a radius of just about 80 light years. That translates into the density of stars in this part of M60-UCD1 being about 15,000 times greater than what's found in Earth's neighborhood in the Milky Way. Astronomers have been trying to determine where these ultra-compact dwarf galaxies fit into the galactic evolutionary chain. Some have suggested they start off not as galaxies but as giant star clusters. The latest results on M60-UCD1 challenge that idea. The new Chandra data indicate that there may be a supermassive black hole at the center of M60-UCD1. If that's the case, then it's unlikely this object could have ever been a star cluster. Instead, the X-ray data point to this galaxy being the remnants of a larger galaxy that had its outer stars ripped away by tidal forces, leaving behind the dense inner core of the galaxy. Other information about M60-UCD1 including its large mass, point to the same conclusion. Regardless, this galaxy is a fascinating object that astronomers will be studying for a long time to come.
[Runtime: 02:12]
(NASA/CXC/A. Hobart)

Related Chandra Images:

• Photo Album: M60-UCD1

2. Tour of NGC 1232
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Throughout the Universe, galaxies collide. Yet despite being a relatively common occurrence, astronomers are still trying to learn more about the details of what happens when these events take place. A new study using NASA's Chandra X-ray Observatory adds a new piece to this cosmic puzzle. The latest result from Chandra reveals a massive cloud of scorching gas in a galaxy about 60 million light years from Earth. The hot gas cloud - which has a temperature of about 6 million degrees -- is likely caused by a collision between a dwarf galaxy and a much larger galaxy called NGC 1232. If further research confirms that this indeed the case, this discovery would mark the first time such a collision has been detected only in X-rays. And, because it might be an effective way to search for similar collisions, this result could have implications for understanding how other galaxies grow.
[Runtime: 01:05]
(NASA/CXC/A. Hobart)

Related Chandra Images:

• Photo Album: NGC 1232

3. Tour of M31
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Many consider Andromeda, also known as Messier 31, to be a sister galaxy to our own Milky Way. At a distance of only 2.5 million light years away, Andromeda is relatively close to our Galaxy. It is also a spiral galaxy like the Milky Way, and has many similar characteristics. However, a new study using data from NASA's Chandra X-ray Observatory has pointed out some interesting differences between these two galaxies when it comes to black holes. After combining over 150 Chandra observations spread over 13 years, researchers discovered 26 new black hole candidates in Andromeda. This is largest number to date found in a galaxy outside our own. Falling into the stellar-mass category, these black holes form when the most massive stars collapse. The result is a black hole that typically has between five and ten times the mass of the Sun. Seven of these black hole candidates are within 1,000 light years of Andromeda's center, more than what is found near the center of our Milky Way's core. This highlights that although Andromeda and the Milky Way are alike in many ways, they do have their differences. Astronomers have long known that the bulge of stars in Andromeda is bigger as is the super massive black hole at its center. Now we know that it may be a better producer of small black holes as well.
[Runtime: 01:45]
(NASA/CXC/J. DePasquale)

Related Chandra Images:

• Photo Album: M31

4. Tour of NGC 6240
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Two large galaxies are colliding and scientists have used Chandra to make a detailed study of an enormous cloud of hot gas that surrounds them. This unusually large reservoir of gas contains as much mass as about 10 billion Suns, spans about 300,000 light years, and radiates at a temperature of more than 7 million degrees. This giant gas cloud, which scientists call a "halo," is located in the system known as NGC 6240. As the galaxies - each about the size and shape of our Milky Way -- merge, the gas contained in individual galaxy has been violently stirred up. This caused a baby boom of new stars that has lasted for at least 200 million years. During this burst of stellar birth, some of the most massive stars raced through their evolution and exploded relatively quickly as supernovas. According to researchers, this created new hot gas enriched with important elements -- such as oxygen, neon, and magnesium -- that expanded into and mixed with cooler gas that was already there. In the future, the two spiral galaxies will probably form one young elliptical galaxy over the course of millions of years. It is unclear, however, how much of the hot gas can be retained by this newly formed galaxy, or if it will be lost to surrounding space. Regardless, the collision in NGC 6240 offers the opportunity to witness a relatively nearby version of an event that was common in the early Universe.
[Runtime: 02.06]
(NASA/CXC/J. DePasquale)

Related Chandra Images:

• Photo Album: NGC 6240

5. Tour of NGC 3627
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The spiral galaxy NGC 3627 is located about 30 million light years from Earth. Astronomers recently completed a survey of galaxies to look for supermassive black holes. Of the 62 galaxies, 37 - including NGC 3627 - were found to have X-ray sources at their centers and are candidates for being powered by supermassive black holes. Seven of these 37 were previously unknown. This result confirms other Chandra studies that show X-ray surveys are particularly good at finding supermassive black holes that are relatively inactive.
[Runtime: 00:43]
(NASA/CXC/A. Hobart)

Related Chandra Images:

• Photo Album: NGC 3627

6. Tour of NGC 922
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In this holiday season of home cooking and carefully-honed recipes, some astronomers are asking: what is the best mix of ingredients for stars to make the largest number of plump black holes? They are tackling this problem by studying the number of black holes in galaxies with different compositions. One of these galaxies is the ring galaxy NGC 922 that was formed by the collision between two galaxies. This collision triggered the formation of new stars in the shape of a ring. Some of these were massive stars that evolved and collapsed to form black holes. Seven of the sources seen in the Chandra image are thought to contain stellar-mass black holes that are at least ten times more massive than the sun, which places them in the upper range for this class of black hole. By comparing NGC 922 to galaxies with different mixtures of elements, astronomers hope to master the ideal recipe for what it takes to make these large black holes.
[Runtime: 1.09]
(NASA/CXC/A. Hobart)

Related Chandra Images:

• Photo Album: NGC 922

7. A Tour of SN 1957D in M83
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Over fifty years ago, a supernova was discovered in M83, a spiral galaxy about 15 million light years from Earth. This supernova was dubbed SN 1957D because it was the fourth one detected in the year of 1957.
[Runtime: 01:13]
(X-ray: NASA/CXC/STScI/K.Long et al., Optical: NASA/STScI)

Related Chandra Images:

• Photo Album: M83

8. Tour of M83
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Since the 1980s, astronomers have known about a mysterious class of objects that they call "ultraluminous X-ray sources," or ULXs. They named them this because these objects give off more X-ray light than most other binary systems where black holes or neutron stars are in orbit around a normal companion star. Recently, scientists using NASA's Chandra X-ray Observatory and optical telescopes spotted a ULX in the spiral galaxy M83 that was acting even more strangely. This ULX increased its output in X-rays by 3,000 times over the course of several years. Using clues found in the X-ray and optical data, researchers think this ULX may be a member of a population of black holes that up until now was suspected to exist but had not been confirmed. These black holes, which are the smaller stellar-mass black holes, are older and more volatile than previously thought.
[Runtime: 1.04]
(NASA/CXC/A. Hobart)

Related Chandra Images:

• Photo Album: M83

9. Tour of NGC 3115
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This is NGC 3115, a galaxy located about 32 million light years from Earth. This composite image contains X-rays from Chandra as well as optical data from the Very Large Telescope. Using the new Chandra image, astronomers have imaged the flow of hot gas as it falls toward the supermassive black hole in the center of NGC 3115. This is the first time such a flow has been clearly imaged in any black hole. The Chandra data also provide evidence that the black hole in NGC 3115 has a mass of about two billion times that of the Sun. This would make NGC 3115 the host of the nearest billion-solar-mass black hole to Earth.
[Runtime: 00:55]
(NASA/CXC/A. Hobart)

Related Chandra Images:

• Photo Album: NGC 3115

10. Tour of Arp 147
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Just in time for Valentine's Day comes a new image of a ring -- not of jewels -- but of black holes. This image shows Arp 147, a pair of interacting galaxies some 430 million light years from Earth, as seen by the Chandra X-ray Observatory and the Hubble Space Telescope. The ring-shaped object on the right is a remnant of a spiral galaxy that collided with the elliptical galaxy to the left millions of years ago. The collision triggered a wave of star formation. Many of these new young stars raced through their evolution in a few million years or less and ended up as supernova explosions or black holes. X-rays from Chandra now reveal a ring of these black holes in the outer arms of the spiral structure. Researchers estimate that the nine sources around the ring are likely 10 to 20 times more massive than the Sun a rather impressive weight for any Valentines gift.
[Runtime: 0.59]
(X-ray: NASA/CXC/MIT/S.Rappaport et al, Optical: NASA/STScI)

Related Chandra Images:

• Photo Album: Arp 147