Category Archives: Hubble

Active Galactic Nucleus


The galaxy above called IC-3639 has an Active Galactic Nucleus that is actually obscured which leads to even more questions.  AGN’s are super-massive black holes (in the order of a million to probably hundreds of million solar masses) that are accreting massive amounts of matter, which is to say “feeding”. The accretion disc makes the Active Galaxies among the brightest objects in terms of electromagnetic radiation, so bright it is not often whether or not a galaxy is active, is in question, IC 3639 is such a galaxy.

A word about black holes in general because some people have a mistaken impression of black holes as marauding monsters roaming the universe looking for innocent planets to swallow up, that just came up on an outing with friends. No, a black holes don’t really do that. In fact if you took a black hole of one-solar-mass and swapped it with our Sun our solar system would just keep right on going just like it does now, aside from light and heat of course, the fabric of space-time would be just as it is now.

From NuSTAR:
IC 3639, a galaxy with an active galactic nucleus, is seen in this image combining data from the Hubble Space Telescope and the European Southern Observatory.

This galaxy contains an example of a supermassive black hole hidden by gas and dust. Researchers analyzed NuSTAR data from this object and compared them with previous observations from NASA’s Chandra X-Ray Observatory and the Japanese-led Suzaku satellite. The findings from NuSTAR, which is more sensitive to higher energy X-rays than these observatories, confirm the nature of IC 3639 as an active galactic nucleus that is heavily obscured, and intrinsically much brighter than observed.

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR’s mission operations center is at UC Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror archive. JPL is managed by Caltech for NASA.

Image and caption: NASA/JPL-Caltech/ESO/STScI

NGC 4696


From Hubble:

This picture, taken by Hubble’s Wide Field Camera 3 (WFC3), shows NGC 4696, the largest galaxy in the Centaurus Cluster.

The new images taken with Hubble show the dusty filaments surrounding the centre of this huge galaxy in greater detail than ever before. These filaments loop and curl inwards in an intriguing spiral shape, swirling around the supermassive black hole at such a distance that they are dragged into and eventually consumed by the black hole itself.

Credit:  NASA, ESA/Hubble, A. Fabian

The Gem

Little gem

The NASA/ESA Hubble Space Telescope had imaged NGC 6818 before, but it took another look at this planetary nebula, with a new mix of colour filters, to display it in all its beauty. By showing off its stunning turquoise and rose quartz tones in this image, NGC 6818 lives up to its popular name: Little Gem Nebula.

This cloud of gas formed some 3500 years ago when a star like the Sun reached the end of its life and ejected its outer layers into space. As the layers of stellar material spread out from the nucleus – the white stellar remnant at the centre of the image – they ended up acquiring unusual shapes.

NGC 6818 features pinkish knotty filaments and two distinct turquoise layers: a bright, oval inner region and, draped over it like sheer fabric, a spherical outer region.

The central star has a faint stellar companion 150 astronomical units away, or five times the distance between the Sun and Neptune. You can just about make this out: if you zoom in to the centre, you’ll notice the white dot in the middle is not perfectly round, but rather two dots very close together.

With a diameter of just over half a light-year, the planetary nebula itself is about 250 times larger than the binary system. But the nebula material is still close enough to its parent star for the ultraviolet radiation the star releases to ionise the dusty gas and make it glow.

Scientists believe the star also releases a high-speed flow of particles – a stellar wind – that is responsible for the oval shape of the inner region of the nebula. The fast wind sweeps away the slowly moving dusty gas, piercing its inner bubble at the oval ends, seen at the lower left and top right corners of the image.

NGC 6818 is located in the constellation of Sagittarius and is about 6000 light-years from Earth. It was first imaged by the Hubble Space Telescope’s Wide Field Planetary Camera 2 in 1997, and again in 1998 and 2000 using different colour filters to highlight
different gases in the nebula.

Credits: ESA/Hubble & NASA; acknowledgement: J. Schmidt (

BOO! It’s a Red Spider


Huge waves are sculpted in this two-lobed nebula called the Red Spider Nebula, located some 3,000 light-years away in the constellation of Sagittarius. This warm planetary nebula harbors one of the hottest stars known and its powerful stellar winds generate waves 100 billion kilometers (62.4 billion miles) high. The waves are caused by supersonic shocks, formed when the local gas is compressed and heated in front of the rapidly expanding lobes. The atoms caught in the shock emit the spectacular radiation seen in this image.

Text credit: ESA (European Space Agency)
Image credit: ESA/Garrelt Mellema (Leiden University, the Netherlands)