Images Credit & Copyright: Credit is displayed with the individual images with links to all at the bottom of the post.
The Vela Supernova Remnant is one of the truly awe inspiring locations in the southern sky. Being very large it’s difficult to observe visually but when captured via long exposure night sky imagery, a whole new picture comes to light. Let’s take a walk through this 55 light year diameter remnant of what was once a star before exploding in one of the most violent acts that the universe has to offer some 12,000 years ago near the dawn of written history. The vela region is very complex and not as clear cut as you might think. For example, the Vela SNR lies within the Gum Nebula (Gum 12); this region is also believed to be a supernova that exploded roughly a million years ago. As we progress, more surprises will reveal themselves to us.
The image above that I headlined this post with was captured by night sky superstar, Robert Gendler. This 30 frame mosaic contains 60 hours of exposure time to generate enough light for us to see this breathtaking region in detail. http://www.robgendlerastropics.com/Velamosaic.html
Let’s get close to this debris field and have a look around. As we do so, see if you can spot these individual features in the full mosaic. I’m going to kick off this tour with NGC 2736 or as it’s popularly known; The Pencil Nebula. This 0.8 light year-long seemingly rolling cloud of debris was impacted by the initial blast and superheated. It has long since cooled yet still hot enough to be visible in images such as this. Moving at a speed of 400,000 mph (650,000 kph), in a single human generation we will be able to detect visually that the pencil has changes locations slightly. This object sometimes goes by the name of Herschel’s Ray as it was discovered by John Herschel in 1835 from South Africa. This image was captured by the European Southern Observatory (ESO) La Silla in Chile’s Atacama Desert. http://www.eso.org/public/news/eso1236/
Next we move to the region centered on the little Gum 15 with the much larger and dimmer Gum 14 at the upper right and the bright Gum 17 at the bottom left. The second image here is a closeup of Gum 15. What role do these regions play in the Vela Supernova Remnant?….well, none.
At roughly 3,000 light years away they’re not affiliated with the Vela SNR and what’s more; they’re not destructive but instead they’re actually HII star forming emission nebulae. At the center of little Gum 15 is the open star cluster Collinder 197 and its brightest member, HD 74804. What about the big fella, Gum 14 at the top right of this image? Yep, that’s an HII star forming emission nebula as well. Also within Gum 14 are Herbig-Haro objects as well as the reflection nebula NGC 2626. The prominent member of this star group is the supergiant HD 73882.
We close by focusing our attention to the bottom left of this image and yet another star forming HII region; Gum 17. This region is believed to be at a distance of about 1,200 light years. That’s if you fall into the camp of those who think that the open star cluster Trumpler 10 is associated with the nebula. If youre in the camp that associates the nebula to star HD 75759, you would place Gum 17 at a distance of 3,200 light years. If you look closely just outside of Gum 17 in the direction of the smaller Gum 15 you can distinguish the open star cluster NGC 2671 and also see little planetary nebula K2-15 just below Gum 17 near the bottom of the image. http://www.eso.org/public/images/eso1420c/ & http://www.eso.org/public/usa/news/eso1420/
Cruising right along through this highly complex region we make a stop at the open star cluster NGC 2547. This cluster is 1,500 light years from Earth and believed to be only 30 million years old. As the ESO writeup put it; that may sound old but if our middle aged Sun were a 40 year old human, this cluster would only be a 3 month old baby. Again, though within line of sight, this cluster is independent of the Vela Supernova Remnant as it’s much more distant. At an apparent magnitude of about 5, have a go at this location with binoculars and it should easily reveal itself to you. http://www.eso.org/public/images/perez-ngc_2547/
We move now to a Mike Sidonio image of the incredibly beautiful region of Gum 19. We see the filaments of the Vela SNR in this image seemingly hovering above Gum 19 like clouds creating the illusion of a peaceful, beautiful team. Well, like most objects constructed of baryonic matter in the universe, this region is a disaster waiting to happen. Once again we have to touch on distances first. The Vela filaments in this image reside about 3,000 light years away while Gum 19 is a much further 22,000 light years distant. This HII star forming region is dominated by a star known as V391 Velorum and it’s a variable blue supergiant that’s unstable and not expected to survive beyond the young age of 10 million years before self-detonating. http://www.pbase.com/strongmanmike2002/vela_snr_double_helix
Here’s a region that I posted about recently; Herbig-Haro 47 (HH47). It’s a three trillion mile long jet of material being fired from a newborn star. The actual star in this image is hidden behind a gas and dust shroud near the left side of this image.
What is a Herbig-Haro (HH) Object?
While newborn stars are busy accreting material like knowledge in order to grow and be the best stars they can be; some of that material is being shot off into the surrounding cosmos from the stars polar regions or perpendicular to the plane of that star in a process called bipolar outflow. When the rapid jets of hot material that can reach many thousands of degrees Kelvin impacts the surrounding material (usually associated with Bok Globules or the same material that helped create the star) it heats that material and produces ionized gas which then renders the jets and shock wave aglow. As the gas that trails the hot shock wave cools, the electrons and ions recombine which in many images, can be seen as a second color within the shockwave itself.
The odd name comes from the two discoverer’s names; American astronomers George Herbig and Mexican astronomer Guillermo Haro. While much is known about these objects such as where they can be found and what they’re composed of, many fundamental questions remain. What causes the star to fire off these jets and what purpose do they serve, are questions that still need to be addressed. The going hypothesis is that they may be associated with the stars magnetic fields and that they may also actually help the stars formation by bleeding off excess angular momentum from the accreting material which would actually help slow and stabilize the system, allowing the protostar to successfully accrete into a successful star. https://www.spacetelescope.org/images/opo9524g/
I really hope you’ve enjoyed our trip around the region known as the Vela Supernova Remnant as it’s a stunningly beautiful region which, as we all know by now was created by the detonation of a massive star. Before we leave, let’s take a look at this freak show. This alien-like structure is the leftovers of a star gone bang. What was once a massive star shining brightly has been transformed into something incredible; a pulsar. The Vela Pulsar actually resides deep within the Vela SNR so, around 1,000 light years away. A pulsar is a neutron star and neutron stars are created when a star goes supernova but instead of the core of the star becoming a black hole, the process is stopped at the door before it can become one. That leaves a pulsar; the most dense object in the universe aside from a black hole itself. It rotates, it rotates fast…..how fast you ask? The Vela Pulsar rotates 11 times per second, spewing out a jet of charged particles from its poles at 70% of the speed of light for almost a light year in each direction. Even more amazing, as they spin, angular momentum causes them to speed up and become extremely small and dense. They’re only about 12 miles across or about the diameter of a major city. Their material is so compact that a sugar cube sized cube of neutron material would weigh 100 million tons on Earth! The Vela pulsar is one of the brightest X-ray sources in the night sky. I will do a full post on this soon but in short, pulsars are neutron stars that rotate extremely fast and are highly magnetic. In this NASA Chandra image, the Vela Pulsar is hidden within the rings of this object, its jets easily visible. http://chandra.harvard.edu/photo/2013/vela/
Just to add a final bit of complexity to this region, as I said before, the Vela Supernova Remnant resides within the Gum Nebula (Gum 12) which stretches well into the constellation Puppis. Well, within line of sight of the Vela SNR is also the Puppis A SNR which is about four times further away or about 6,500 light years away.
NAME: Vela Supernova Remnant. Pulsar
WHAT IS IT?: The remains of a star that exploded approximately 12,000 years ago near the dawn of written history.
HOW FAR AWAY IS IT?: 800 light years.
HOW BIG IS IT?: Roughly 55 light years in diameter and 8 degrees of the night sky or 16 x the diameter of the full moon.
APPARENT MAGNITUDE: A dim 12.
WHERE IS IT (General): Constellation Vela (The Sails) within the Gum Nebula.
WHERE IS IT? (Exact RA/DEC J2000): RA 08h 35m 20.60s / DEC -45° 10‘ 35“.
Vela Supernova Remnant; Robert Gendler: http://www.robgendlerastropics.com/Velamosaic.html
ESO Pencil Nebula: http://www.eso.org/public/news/eso1236/
ESO Gum 14 (RCW 27), Gum 15 (Collinder 197), Gum 17 (RCW 33): http://www.eso.org/public/images/eso1420c/
ESO Gum 15 closeup: http://www.eso.org/public/usa/news/eso1420/
ESO NGC 2547: http://www.eso.org/public/images/perez-ngc_2547/
Gum 19; Mike Sidonio: http://www.pbase.com/strongmanmike2002/vela_snr_double_helix
Hubblesite News Center HH47:
NASA CHANDRA Harvard; Vela Pulsar: http://chandra.harvard.edu/photo/2013/vela/