Cosmic Leftovers


galex-view-m81_m82The Hubble Space Telescope has resolved some strange objects nicknamed “blue blobs” and found them to be brilliant blue clusters of stars born in the swirls and eddies of a galactic smashup 200 million years ago. These “blue blobs” exist along a wispy bridge of gas strung among three colliding galaxies, M81, M82, and NGC 3077 about 12 million light-years away from Earth. This is not a place astronomers expect to find star clusters because the gas filaments should be too thin to allow enough material to accumulate and actually build so many stars. The star clusters in this diffuse structure might have formed from gas collisions and subsequent turbulence which locally enhanced the density of the gas streams.

Image Credit: NASA, ESA

A Galaxy Seen Head On


NGC1309_HLANGC 1309 lies on the banks of the constellation Eridanus (The River) about 100 million light-years away. It about 30,000 light-years across or about one third the size of our Milky Way galaxy. Bluish clusters of young stars and dust lanes trace out NGC 1309’s spiral arms, winding around an older yellowish star population at the galaxy’s core.

NGC 1309’s recent supernova and Cepheid variable stars are used to derive calibration data for the expansion of the Universe.

Image Credit: NASA / ESA

Watching a Supernova Remnant Grow


This time-lapse video shows the movement of a supernova remnant that erupted approximately 1,700 years ago. The gaseous remains of an exploded star named 1E 0102.2-7219, is in the Small Magellanic Cloud, a satellite galaxy of our Milky Way. The opening frame shows ribbons of glowing gaseous clumps that make up the remnant. The video then toggles between a pair of black-and-white images taken 10 years apart, showing subtle shifts in the strands of gas over the decade. 

Video Credit: NASA / ESA / A. Pagan (STScI) / J. Banovetz and D. Milisavljevic (Purdue University)

M9


Hubble image of Messier 9M9 is one of the globular clusters closest to the center of the Milky Way Galaxy, only around 5,500 light-years from the galactic core. It’s about 25,800 light-years from Earth.

M9 has an apparent magnitude of 7.9, an angular size of 9.3′, and can be viewed with a small telescope. It is one of the nearer globular clusters to the center of the galaxy as is around 5,500 light-years from the Galactic Core. Its distance from Earth is 25,800 light-years.

The total luminosity of this cluster is around 120,000 times that of the Sun. It has an apparent magnitude of 7.9, so it can be viewed with a small telescope.

Image Credit: NASA

The Cartwheel Galaxy


cartwheel_galaxyThe Cartwheel Galaxy (aka ESO 350-40) is a ring galaxy about 500 million light-years away in the constellation Sculptor. It is about 150,000 light-years diameter. The galaxy was once a normal spiral galaxy before it apparently underwent a head-on collision with a smaller companion approximately 200 million years ago. When the other galaxy passed through the Cartwheel Galaxy, the collision caused a powerful shock wave. Moving at high speed, the shock wave swept up gas and dust, creating a starburst around the galaxy’s center portion forming the bluish ring around the central brighter portion. The galaxy appears to be retaking the form a spiral galaxy with thin arms beginning to spread from its central core. The Cartwheel contains an exceptionally large number of black hole binary X-ray sources because many massive stars formed in the ring.

Image Credit: ESA / NASA

A LINER in Space


This is no supermodel spiralNGC 4102 lies in the northern constellation of Ursa Major (The Great Bear). It contains what is known as a LINER, or low-ionization nuclear emission-line region. That means its nucleus emits particular types of radiation, emission from weakly-ionised or neutral atoms of certain elements. That’s not very unusual. About one third of all nearby galaxies are thought to be LINER galaxies.

Many LINER galaxies also contain intense regions of star formation. This is thought to be intrinsically linked to their galactic centers, but the reason why is still a mystery. It may be that the starbursts pour fuel inwards to fuel the LINERs, or this active central region might trigger the starbursts. NGC 4102 does indeed contain a starburst region near its center where stars are being created at a more rapid rate than in a normal galaxy.

Image Credit: NASA / ESA

Caldwell 78


This is Caldwell 78 (aka NGC 6541), a globular star cluster roughly 22,000 light-years from Earth. The cluster is bright enough that backyard stargazers in the Southern Hemisphere can usually spot it with binoculars.

Image Credits: NASA / ESA/ G. Piotto (Università degli Studi di Padova)
Processing: Gladys Kober (NASA / Catholic University of America)

Still More Cosmic Leftovers


This is a visualization of the supernova remnant known as SNR 0509-67.5 as seen by the Hubble Space Telescope. The delicate sphere of gas is being formed by the expanding blast wave from a supernova in the Large Magellanic Cloud, a small galaxy about 160,000 light-years from Earth. The ripples in the shell’s surface may be caused by either subtle variations in the density of the ambient interstellar gas, or they are possibly driven from the interior by pieces of the ejecta. The bubble-shaped shroud of gas is 23 light-years across and is expanding at more than 5,000 km/s.

Video Credit: NASA /ESA / G. Bacon, T. Borders, L. Frattare, Z. Levay, and F. Summers (STScI)

A Fading Nebula


Data from the Hubble Space Telescope reveal that the nebula Hen 3-1357 (aka the Stingray Nebula) has faded dramatically over the past two decades. These two strikingly different images of the nebula were captured 20 years apart. The image on the left was taken in March, 1996, and shows the nebula’s central star in the final stages of its life. The gas being puffed off by the dying star is much brighter than the gas photographed in January, 2016. It’s very rare to see a nebula change so quickly.

Image Credits: NASA / ESA / B. Balick (University of Washington), M. Guerrero (Instituto de Astrofísica de Andalucía), and G. Ramos-Larios (Universidad de Guadalajara)

Cosmic Leftovers


This tangled web is an object known as SNR 0454-67.2. It’s a supernova remnant created after a massive star ended its life in a cataclysmic explosion and threw off its constituent material out into surrounding space. SNR 0454-67.2 lies in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. The remnant is probably the leftovers from a Type Ia supernova explosion. A Type IA supernova is the death of a white dwarf star that grown by siphoning material from a stellar companion until it reached critical mass and exploded.

Image Credit: ESA / NASA

NGC 986


A spiral in a furnaceNGC 986 is found in the constellation of Fornax (The Furnace), located in the southern sky. NGC 986 is around 56 million light-years away, and its golden center and barred swirling arms are clearly visible in this image assembled from data captured by Hubble’s Wide Field and Planetary Camera 2. (The stars in the upper right appear a little fuzzy because a gap in the Hubble data was filled in with images from ground-based telescopes. The view  is accurate, but the resolution is no match for Hubble.)

Barred spiral galaxies are spiral galaxies with stars forming a central bar-shaped structure. NGC 986 has the characteristic S-shaped structure of this type of galaxy. Young blue stars can be seen dotted through the galaxy’s arms, and the core is also alight with star formation.

Image Credit: NASA / ESA

Hubble Looks at Hubble’s


NGC 2261 is an odd nebula named for Edwin Hubble, who studied it early last century. It’s appearance can change over short periods of time. Hubble’s Variable Nebula is a reflection nebula made of gas and fine dust moving out from the star R Monocerotis. The faint nebula is about one light-year across and lies about 2500 light-years away in the constellation of Monocerotis (the Unicorn). The leading explanation for the nebula’s rapid changes suggests that dense knots of opaque dust is passing close to R Mon and cast moving shadows onto the reflecting dust seen in the rest of the nebula.

Image Credit: NASA / ESA
Data: Mark Clampin (GSFC)
Processing & License: Judy Schmidt, CC BY 2.0

A Ghost Ring Sight


NGC 6369 is a planetary nebula also known as the Little Ghost Nebula. Planetary nebulae aren’t related to planets. They’re gaseous shrouds created at the end of a Sun-like star’s life as the dying star’s outer layers expand while its core shrinks to become a white dwarf. The white dwarf radiates strongly at ultraviolet wavelengths, powering the expanding nebula’s glow. NGC 636’s main round structure is about a light-year across, and the glow from its ionized oxygen, hydrogen, and nitrogen atoms are colored blue, green, and red respectively. The Little Ghost Nebula offers a glimpse of the likely fate of our Sun which could produce its own planetary nebula about 5 billion years from now.

Image Credit: NASA / ESA

Our Next Door Neighbor


proxima_centauriThe star shown in this Hubble image isn’t very bright. It can’t be seen with the naked eye. Yet, it is our Sun’s closest stellar neighbor. Proxima Centauri, in the constellation of Centaurus (The Centaur), is just over four light-years from Earth. It is quite small compared to other stars, only about an eighth of the mass of the Sun.

Its average luminosity is very low, but, on occasion, its brightness increases. It is what is known as a “flare star,” prone to random and dramatic changes in brightness. Convection processes in the star’s interior not only trigger brilliant bursts of stellar output, but that stirring, combined with other factors, means that Proxima Centauri has a rather extended life expectancy. Astronomers predict that this star will remain middle-aged—what’s known as a “main sequence” star—for another four trillion years. That’s roughly 300 times the age of the current Universe.

Image Credit: NASA / ESA

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