Mergers and Acquisitions and Blue Blobs

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 3077about 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 Top Down View of a Spiral Galaxy

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 have been used to derive calibration data for the expansion of the Universe.

Image Credit: NASA / ESA

AD 5,000,000,000 (More of Less)

The Little Ghost Nebula offers a glimpse of the fate of our Sun, which could produce its own planetary nebula about 5 billion years from now.  Round and planet-shaped, the nebula (AKA, NGC 6369) is also relatively faint—thus the nickname Little Ghost Nebula. Planetary nebulae really have nothing to do with planets. They are created at the end of a sun-like star’s life as its outer layers expand into space while the star’s core shrinks to become a white dwarf. The transformed white dwarf star in the middle of the nebula radiates strongly at ultraviolet wavelengths and powers the expanding nebula’s glow. This nebula’s main ring structure is about a light-year across and the glow from ionized oxygen, hydrogen, and nitrogen atoms are colored blue, green, and red respectively.

BTW. about a billion years earlier, the Milky Way and Andromeda galaxies will have merged, probably causing significant changes in the galactic neighborhood.

Image Credit: NASA/Hubble Heritage Team

frEGGs

Free-floating Evaporating Gaseous Globules (frEGGs) were first seen in Hubble’s famous image of the Eagle Nebula. Because these knots of cold interstellar gas are dark, we only notice them near where new stars are forming and emitting intense UV light which erodes away. most of the neighboring gas.

This Hubble image also features a pair of young, giant stares. The one on the left is a giant O-type blue-white; the one right is a supergiant B-type. Both types burn their fuel quickly, and supergiants end up as supernovae.

Image Credit: NASA / ESA

Deathwatch for a Star

etacarinae_hst_960Eta Carinae may be about to explode. We’re not sure when—it might be next year, it might be one million years from now. The star’s mass of roughly 100 times our Sun’s makes it an excellent candidate for a full blown supernova, and about 150 years ago, Eta Carinae underwent an unusual outburst becoming one of the brightest stars in the southern sky. Eta Carinae is also the only star currently known to be emitting light from a natural laser. This Hubble image brings out details in the unusual nebula that surrounds this rogue star—two distinct lobes, a hot central region, and strange radial streaks. The lobes are filled with lanes of gas and dust which absorb the blue and ultraviolet light emitted near the center. The streaks remain unexplained.

Eta Carinae is in the constellation Carina. Carina is Latin for the keel of a ship, and it was formerly part of the larger constellation of Argo Navis (the ship Argo) until that constellation was divided into three pieces, the other two being Puppis (the poop deck), and Vela (the sails of the ship).

Image Credit: NASA

A Reflection Nebula

Reflection Nebula in OrionNGC 1999 is a reflection nebula. A reflection nebula doesn’t emit light on its own. Much like fog around a lamp post, a reflection nebula shines because the light from an embedded source illuminates its dust. NGC 1999 lies close to the Orion Nebula in a region of our galaxy about 1,500 light-year away where new stars are being formed. NGC 1999 is lit by a bright, recently formed star, visible just left of center in this Hubble photo. the star’s white color is caused by its high surface temperature (about 10,000 °C, twice that of the Sun).

Image Credit: NASA

A Holiday Wreath in Space

RS PuppisThis Hubble Space Telescope image resembles a holiday wreath full of sparkling lights. The bright star RS Puppis is at the center of the image and is wrapped in a cocoon of reflective dust lit by the star. RS Puppis is huge, ten times more massive than our sun and 200 times larger. It’s one of the most luminous stars in the class of known as Cepheid variables and brightens and dims over a six-week cycle. Its average intrinsic brightness is 15,000 times greater than our Sun’s.

The surrounding nebula flickers in brightness as pulses of light from the Cepheid move outwards. Hubble has taken a series of photos of light flashes rippling across the nebula in a phenomenon known as a “light echo.” Several can be seen in this picture, most easily the ones moving toward seven o’clock. Even though light travels at around 300,000 km/s, the nebula is so large that reflected light can actually be photographed traversing the nebula. Using these reflections, astronomers are able to measure these light echoes and accurately compute the distance to RS Puppis—6,500 light-years (with a margin of error of only one percent).

Image Credit: NASA

Zooming in on CW Leonis

CW Leonis is a carbon star, a luminous red giant, whose atmosphere contains more carbon than oxygen. It’s believed to be in a late stage of its life, blowing off its own sooty atmosphere to eventually form a white dwarf.

Video Credit: ESA / Hubble, NASA, Dark Energy Survey / DOE / FNAL / NOIRLab / NSF / AURA, Digitized Sky Survey 2, E. Slawik, N. Risinger, M. Zamani
Music: tonelabs – Happy Hubble (tonelabs.com)
Creative Commons Attribution license (reuse allowed)

Two Clusters and White Dwarfs

Astronomers compare the cooling stars in two massive globular clusters, M13 and M3, to study the evolution of white dwarfs. These two clusters are about the same age and have roughly the same percentage of elements heavier than helium, but their populations of the kind of stars which will end their lives as white dwarfs are different. Thus, M13 and M3 form a natural laboratory the lives pf white dwarfs.

Image Credit: NASA / ESA

Cosmic Leftovers

DEM L 190These delicate filaments are actually sheets of debris from a stellar explosion in a neighboring galaxy, the Large Magellanic Cloud (LMC), a small companion galaxy to the Milky Way visible from the southern hemisphere. This remnant, know as N49 or DEM L 190, is from a massive star that died in a supernova blast thousands of years ago. This filamentary material will eventually be recycled into building new generations of stars in the LMC. Our own Sun and planets were formed from similar debris of supernovae that exploded in our own galaxy billions of years ago.

These filaments harbor a very powerful spinning neutron star that may be the central remnant from the supernova. It is quite common for the core of an exploded supernova star to become a spinning neutron star (or pulsar) after the immediate shedding of the supernova’s outer layers.  The pulsar in N 49 is spinning at a rate of once every 8 seconds. It also has a super-strong magnetic field a thousand trillion times stronger than Earth’s magnetic field. This places this star into the exclusive class of objects called “magnetars.”

Image Credit: NASA