NGC 362

Youthful NGC 362Globular clusters offer some of the most spectacular sights in the night sky. These ornate spheres contain hundreds of thousands of stars, and reside in the outskirts of galaxies. The Milky Way contains over 150 globular clusters, and NGC 362 is one of the more unusual ones.

As stars make their way through life they fuse elements together in their cores, creating heavier and heavier elements—astronomers call anything further up the period table than helium a “metal”—in the process. When stars die, they flood their surroundings with the material they have formed during their lifetimes, enriching the interstellar medium with metals. New stars that form from the remnants of older stars contain higher proportions of metals than their older relatives. The stars in NGC 362 contain a surprisingly high metal content, indicating that it is younger, second generation stars. Most globular clusters are much older than the majority of stars in their host galaxy, but NGC 362 bucks the trend, with an age lying between 10 and 11 billion years old. That makes them newbies compared the average age of a star in the Milky Way, 13 billion years.

Image Credit: ESA / NASA

Mergers and Acquisitions

In this image, galaxy NGC 2799 appears to being pulled into the center of its neighbor NGC 2798. Interacting galaxies such as these may eventually merger or form a unique pairing. For now, stars from NGC 2799 seem to be falling into NGC 2798 almost like droplets of water.

Galactic mergers usually take place over time scales of several hundred million to a billion or more years. While one or both of the galaxies may cease to exist as an independent entity, the vast space between stars means that stellar collisions are unlikely, so the individual stars typically drift past each other. Our Milky Way is on track to merge with the Andromeda galaxy in four billion years or so.

Image Credit: NASA / ESA

NGC 3310

NGC 3310NGC 3310 is a grand design spiral galaxy in the constellation Ursa Major. It is also a starburst galaxy. (Starburst galaxies are undergoing an exceptionally high rate of star formation.) NGC 3310 probably collided with one of its satellite galaxies about 100 million years ago, triggering widespread star formation. The ring clusters of NGC 3310 have been undergoing starburst activity for at least the last 40 million years.

Image Credit: NASA / ESA

Mergers and Acquisitions

NGC 2623 is really two galaxies that are merging to become one. The pair lies some 300 million light-years distant toward the constellation Cancer. The are in the final stages their merger. The violent encounter between two galaxies that once may have been similar to our Milky Way has resulted in widespread star formation near a luminous core and along tidal tails. The opposing tidal tails extend more than 50,000 light-years from the combined nucleus and are filled with dust, gas, and young blue star clusters. Accretion by a supermassive black hole drives the activity near the nucleus. Star formation and the active galactic nucleus cause NGC 2623 to shine brightly across the spectrum.

BTW, in about 4 billion years, our galaxy, The Milky Way, will merge with the Andromeda Galaxy.

Image Credit: NASA / ESA

NGC 4414, An Unbarred Spiral Galaxy

ngc-4414NGC 4414 is an unbarred spiral galaxy about 62 million light-years away in the constellation Coma Berenices. It has short segments of spiral structure but lacks the dramatic well-defined spiral arms of a grand design spiral galaxy. NGC 4414 is also a very isolated galaxy without signs of past interactions with other galaxies.

Image Credit: NASA / ESA

Zooming in on a Supernova

This video zooms into the galaxy catalogued as NGC 2525. The Hubble Space Telescope captured a series of time-lapse images of a supernova in that galaxy in 2018. It appears as a very bright star located on the outer edge of one of the spiral arms. The supernova initially outshining the brightest stars in the galaxy, but it fades into obscurity during the year of observations.

Video Credit: ESA

A Dwarf Flock

dwarf galaxyThis Hubble image looks a bit like a flock of birds. It’s really a picture of a dwarf galaxy called ESO 540-31 a bit more than 11 million light-years from Earth in the constellation of Cetus (The Whale). All those galaxies in the background are much further away.

Dwarf galaxies are some of the smaller and dimmer members of the galactic family with only a few hundred million stars or so. Although that may seem like a large number, it is tiny compared to spiral galaxies like our Milky Way, which are made up of hundreds of billions of stars.

Image Credit: NASA / ESA

Jupiter in Visible Light and UV

From time to time, the Hubble Space Telescope takes observes the four gas giant planets in the Solar System in a ongoing survey of the outer planets’ weather systems. It took the last images of Jupiter in that series on 25 August. This video opens with a view of Jupiter in visible light. Then, a false-color UV view wipes across the planet, followed by a wipe back to visible light.

Video Credit: NASA

A Pending Merger?

The giant elliptical galaxy M60 and the spiral galaxy NGC 4647 make an odd couple Hubble Space Telescope image. They’re found in a region of space where galaxies tend to gather, on the eastern side of the nearby Virgo Galaxy Cluster. About 54 million light-years away, M60’s simple egg-like shape about 120,000 light-years across is created by its randomly swarming older stars. NGC 4647’s young blue stars, gas and dust are an organized spiral, winding arms rotating in a flattened disk spanning 90,000 light-years. It’s about the same size as our galaxy, the Milky Way. NGC 4647 is more distant than M60, around 63 million light-years from Earth. The pair of galaxies which is known as Arp116 may be close enough to be on the verge of a significant gravitational encounter.

Image Credit: NASA / ESA

The Cygnus Loop Nebula

20,000 years ago there was a supernova explosion in the constellation of Cygnus. Its shockwave is still expanding into interstellar space. The impact of the fast moving wall of gas on a stationary cloud has heated it causing it to glow with visible light as well as high energy radiation. The result is the nebula known as the Cygnus Loop (NGC 6960/95). The colors in this Hubble Space Telescope image indicate emission from different kinds of atoms excited by the shock: oxygen-blue, sulfur-red, and hydrogen-green.

There’s a picture of the Cygnus Loop in UV here.

Image Credit: NASA / ESA

NGC 1805

This tight grouping of thousands of stars is located near the edge of the Large Magellanic Cloud, a satellite galaxy of our own Milky Way. The stars orbit closely to one another, like bees swarming around a hive. In the dense center of one of these clusters, stars are 100 to 1,000 times closer together than the nearest stars are to our Sun, making planetary systems around them unlikely.

Usually, globular clusters contain stars that are born at the same time. NGC 1805 is unusual because it contains two different populations of stars with ages millions of years apart. Observing such clusters of stars can provide data on how stars evolve and on what factors determine whether they end their lives as white dwarfs or explode as supernovae.

Image Credit: NASA / ESA

A Galaxy on Edge

NGC 2188 is estimated to be just half the size of our Milky Way, about 50,000 light-years across.  Although we see it on edge, astronomers have determined that it’s a barred spiral galaxy by studying the distribution of the stars in the inner central bulge and the outer disk and by observing the stars’ colors.

NGC 2188 in the constellation Columba (the Dove). That constellation was named in the late 1500s after the dove that brought an olive leaf back to Noah’s ark. Coumbia a small constellation with many faint yet beautiful stars and astronomical objects.

Image Credit: NASA / ESA

A Distorted Spiral

A galactic maelstromThis is Messier 96, a spiral galaxy a bit more than 35 million light-years away in the constellation of Leo (The Lion). It is roughly the same mass and size as the Milky Way, but unlike our more or less symmetrical galaxy, M96 is lopsided. Its dust and gas are unevenly spread throughout its weak spiral arms, and its core is not exactly at the apparent galactic center. Its arms are also asymmetrical, perhaps because of the gravitational pull of other galaxies within the same group as Messier 96.

Image Credit: ESA / NASA