Most of NGC 5189 is knotty and filamentary in its structure. As a result of the mass-loss process, the planetary nebula has been created with two nested structures, tilted with respect to each other, that expand away from the center in different directions.
This double bipolar or quadrupolar structure could be explained by the presence of a binary companion orbiting the central star and influencing the pattern of mass ejection during its nebula-producing death throes. The remnant of the central star, having lost much of its mass, now lives its final days as a white dwarf.
The bright golden ring that twists and tilts through the image is made up of a large collection of radial filaments and cometary knots. These are usually formed by the combined action of photo-ionizing radiation and stellar winds.
Massive Star Makes Waves
Like a ship plowing through still waters, the giant star Zeta Ophiuchi is speeding through space, making waves in the dust ahead. NASA’s Spitzer Space Telescope has captured a dramatic, infrared portrait of these glowing waves, also known as a bow shock.
Astronomers theorize that this star was once sitting pretty next to a companion star even heftier than itself. But when that star died in a fiery explosion, Zeta Ophiuchi was kicked away and sent flying. Zeta Ophiuchi, which is 20 times more massive and 80,000 times brighter than our sun, is racing along at about 24 kilometers per second.
In this infrared view Zeta Ophiuchi appears as the bright blue star at center. As it charges through the dust, which appears green, fierce stellar winds push the material into waves. Where the waves are the most compressed, and the warmest, they appear red.
Hubble sees a galaxy hit a bullseye
Bright pink nebulae almost completely encircle a spiral galaxy in this Hubble Space Telescope image of NGC 922. The ring structure and the galaxy’s distorted spiral shape result from a smaller galaxy scoring a cosmic bull’s-eye, hitting the center of NGC 922 some 330 million years ago.
NGC 922’s current unusual form is the result of a cosmic collision with a smaller galaxy named 2MASXI J0224301-244443, which plunged right through the heart of NGC 922 and shot out the other side. As the smaller galaxy passed through the middle of NGC 922, it set up gravitational ripples that disrupted the clouds of gas and triggered the formation of new stars whose radiation then lit up the remaining gas.
The bright pink color of the resulting nebulae is a characteristic sign of this process and is emitted by excited hydrogen gas (the dominant element in interstellar gas clouds). NGC 922 lies 157 million light-years away from Earth.
This face-on galaxy, lying 45 million light-years away from Earth in the southern constellation of Fornax, is particularly attractive for astronomers. NGC 1097 is a Seyfert galaxy. Lurking at the very centre of the galaxy, a supermassive black hole 100 million times the mass of our Sun is gradually sucking in the matter around it. The area immediately around the black hole shines powerfully with radiation coming from the material falling in.
The distinctive ring around the black hole is bursting with new star formation due to an inflow of material toward the central bar of the galaxy. These star-forming regions are glowing brightly thanks to emission from clouds of ionised hydrogen. The ring is around 5000 light-years across, although the spiral arms of the galaxy extend tens of thousands of light-years beyond it.
The Needle Galaxy
IC 2233 is a prime example of a super-thin galaxy, where the galaxy’s diameter is at least ten times larger than the thickness. These galaxies consist of a simple disc of stars when seen edge on. This orientation makes them fascinating to study, giving another perspective on spiral galaxies. An important characteristic of this type of objects is that they have a low brightness and almost all of them have no bulge at all.
The brilliant cascade of stars through the middle of this image is the galaxy ESO 318-13 as seen by the Hubble Space Telescope. Despite being located millions of light-years from Earth, the stars captured in this image are so bright and clear you could almost attempt to count them.
Galaxies are largely made up of empty space; the stars within them only take up a small volume, and providing a galaxy is not too dusty, it can be largely transparent to light coming from the background. This makes overlapping galaxies like these quite common.
ALMA Sheds Light on Planet-Forming Gas Streams
Left: observations made with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope of the disc of gas and cosmic dust around the young star HD 142527, showing vast streams of gas flowing across the gap in the disc. These are the first direct observations of these streams, which are expected to be created by giant planets guzzling gas as they grow, and which are a key stage in the birth of giant planets.
The dust in the outer disc is shown in red. Dense gas in the streams flowing across the gap, as well as in the outer disc, is shown in green. Diffuse gas in the central gap is shown in blue. The gas filaments can be seen at the three o’clock and ten o’clock positions, flowing from the outer disc towards the centre.
The dense gas observed is HCO+, and the diffuse gas is CO. The outer disk is roughly two light-days across. If this were our own Solar System, the Voyager 1 probe — the most distant manmade object from Earth — would be at approximately the inner edge of the outer disk.
Right: artist’s impression of the disc and gas streams, for illustration.
A Splendor Seldom Seen
On Oct. 17, 2012, during its 174th orbit around the gas giant, Cassini was deliberately positioned within Saturn’s shadow, a perfect location from which to look in the direction of the sun and take a backlit view of the rings and the dark side of the planet.
Looking back towards the sun is a geometry referred to by planetary scientists as “high solar phase;” near the center of your target’s shadow is the highest phase possible. This is a very scientifically advantageous and coveted viewing position, as it can reveal details about both the rings and atmosphere that cannot be seen in lower solar phase.
(21 Dec. 2012) —- As the International Space Station and Soyuz TMA-07M spacecraft were making their relative approaches on Dec. 21, one of the Expedition 34 crew members on the orbital outpost captured this photo of the Soyuz (lower left) and a gibbous moon (upper right).
City Lights Illuminate the Nile
On October 13, 2012, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured this nighttime view of the Nile River Valley and Delta. This image was acquired near the time of the new Moon, and little moonlight was available to brighten land and water surfaces.
Whirling Southern Star Trails over ALMA
Babak Tafreshi, one of the ESO Photo Ambassadors, has captured the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) under the southern sky in another breathtaking image. The photograph was taken on the Chajnantor Plateau, at an altitude of 5000 metres in the Chilean Andes.