NGC 2481

ngc-2841NGC 2841 lies 46 million light-years away in the constellation of Ursa Major. It currently has a relatively low star formation rate compared to other spirals that are ablaze with emission nebulae. Notably missing are pinkish emission nebulae that accompany new star birth. It is likely that the radiation and supersonic winds from fiery, super-hot, young blue stars cleared out the remaining gas, and  shut down further nearby star formation. MGC 2481 is prime example of a flocculent spiral galaxy, one whose arms are patchy and discontinuous. It has no grand design structure apparent when seen in visible light as in this Hubble image, although some inner spiral arms can be seen in the near infrared.

Image Credit: NASA / ESA

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)


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

A Star That’s Falling Apart

VY Canis MajorisAstronomers have studied VY Canis Majoris, a red supergiant star that is also classified as a hypergiant because of its very high luminosity, for more than a century. The star is located 5,000 light-years away. It is 500,000 times brighter and about 30 to 40 times more massive than the Sun. If VY Canis Majoris were at the center of our Solar System, its surface could extend to the orbit of Saturn. The star is also in the process of falling apart, and astronomers have learned that its gaseous outflows are more complex than originally thought.

The star has had many outbursts as it nears the end of its life, and the eruptions have formed loops, arcs, and knots of material moving at various speeds and in many different directions. The outermost material was ejected about 1,000 years ago, while a knot near the star may have been ejected as recently as 50 years ago

The typical red supergiant phase of a dying star lasts about 500,000 years as the massive star becomes a red supergiant that has exhausted the hydrogen fuel at its core. As the core contracts under gravity, the outer layers expand, the star’s diameter grows as much as 100 times larger, and it begins to lose mass at a higher rate. VY Canis Majoris has probably already shed about half of its mass, and it will eventually explode as a supernova.

Image Credit: NASA

A Cloud of Cosmic Chaos

This composite view of the Orion Nebula was assembled using imaged from the Hubble and Spritzer Space Telescopes. Hubble’s visible light and UV images show hydrogen and sulfur that have been ionized but intense UV radiation from a group of massive stars in this star-forming region. Spitzer’s infrared data reveals carbon-rich molecules in the cloud. And both sets of images are filled with a rainbow of dots of stars.

Image Credit: NASA

Baby Stars

LH_95These swirls of gas and dust and the stars clustered in and around them are know as LH 95. It a region of low-mass, infant stars and their much more massive stellar neighbors found in the Large Magellanic Cloud.

The largest stars in LH 95 (those with at least 3X the mass of the Sun) generate strong stellar winds and high levels of UV radiation that heat the surrounding interstellar gas. The result is a bluish nebula of glowing hydrogen expanding outward into the molecular cloud that originally collapsed to form these massive stars. However, some dense parts of this star-forming region remain intact despite the stellar winds. The appear as dark dusty filaments in the picture. These dust lanes absorb some of the blue light emitted by the stars behind them causing them appear redder. Other parts of the molecular cloud have contracted to form infant stars, the fainter of which have a high tendency to cluster.

Image Credit: NASA

A Big Cluster of Stars Near the Galactic Center

hs-1999-30-b-full_jpgThis star cluster lurks less than 100 light-years from the very center of our galaxy. With an equivalent mass greater than 10,000 stars like our Sun, the monster cluster is 10 times larger than a typical young star clusters found in the Milky Way. This cluster is destined to be ripped apart in just a few million years by gravitational tidal forces in the galaxy’s core, but during its brief lifespan, it will shine more brightly than almost every other star cluster in the galaxy.

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 Dwarf and Its Debris

IDL TIFF fileThis visible-light image of the debris disk around the red dwarf star AU Microscopii hints that planets may be forming or might already exist within it. The disk glows in light reflected by tiny grains of dust resulting from  the collisions of asteroids and comets. This debris disk is more than 40 billion miles across. The star at the center is quite young, about 12 million years old. It is only 32 light-years from Earth which makes its disk the closest yet seen in reflected starlight. It is also the first disk imaged around an M-type red dwarf, the most common type of star in the stellar neighborhood around the Sun.The disk has been cleared of dust within about a billion miles of the star. Images taken by Hubble (including this one) confirm that the disk is warped and has small variations in density that may have been caused by the tugging of an unseen companion, perhaps a large planet. That would be consistent with presence of the inner gap as well.

This debris disk is unusual in that it is the only one known that appears bluer than the star it surrounds. This possibly could it having a greater proportion of very small grains of dust  than other such disks. Smaller grains scatter blue light better than red. The surplus of small grains may be caused by the star not being bright enough to blow away tiny particles. Brighter, hotter stars would produce sufficient radiation to push small dust grains out of the disk and out into interstellar space

Image Credit: NASA

A Dying Star

he2-47This Hubble image is of the planetary nebula He 2-47, the remnant of a dying star. These gaseous clouds are created when stars in the last stages of life cast off their outer layers of material into space. Hen 2-47’s six lobes of gas and dust that suggest that the central star of the nebula ejected material at least three times in different directions. During each ejection, the paired jets of gas pointed in opposite directions, eventually giving the nebula it’s present shape.

Image Credit: 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)