The science of astronomy is fascinating in that it involves some of the most bizarre concepts in nature.   But, it can be one of the most frustrating fields of study because we must do everything at a distance.  We can’t touch a star.  We can’t see the evolution of most events in the cosmos because the time they take far exceeds our meager lifetimes. (That is, short of an event like a supernova.) Everything we know about the cosmos has been learned by observation via the electromagnetic spectrum, historically in the visible wavelengths and today we cover the entire electromagnetic spectrum.   It is with these observations, coupled with a basic understanding of physics and chemistry learned on Earth, along with theories developed by some very intelligent people that have led to new discoveries in the cosmos.

It has been theorized that stars that orbit a black hole, (like the ones that move around the black hole at the center of our galaxy) may eventually be pulled into the black hole.   This unfortunate star would be ripped apart by the tidal forces exerted on it from the black hole, and its remains would be pulled past the event horizon into the waiting singularity.  This star stuff would release tremendous amounts of energy as it spiraled down into the black hole, moving faster and faster and approaching relativistic speeds.  This energy would be radiated away from the black hole in high energy jets that are perpendicular to the disk of debris falling into the black hole.   This is theory.  We haven’t actually seen this happen – yet.

An event that was documented on March 28, 2011 by the Swift gamma-ray telescope (gamma-ray burst (GRB) 110328A), followed up in the visual part of the spectrum by the Hubble telescope and finally confirmed by the Chandra X-ray telescope may have identified such an event.   The object located in a galaxy 3.8 billion lightyears (ly) from us in the constellation of Draco, visible from the northern hemisphere.   This is what Swift, Hubble and finally Chandra saw as they hunted down the source of the gamma rays:

(HubbleSite.org)

       The Swift telescope picked up on a gamma-ray flash and documented a series of flashes, which instead of getting dimmer actually got more intense.   This is not typically seen. When a star goes supernova it emits an enormous burst of energy that fades over the a period of 3-4 weeks or more as indicated in the graph below.

      What Swift saw was this:

(HubbleSite.org)

      Distinctly different.   If the theory is correct then we are seeing these bursts of energy because the orientation of the black hole relative to Earth is such that these jets point our way.

The proposed scenario that matches up with the observation is depicted in the image below:

(HubbleSite.org )

      Frustratingly, we can’t see this!  We can only surmise from the data that this is what is happening at the core of this galaxy 3.8 billion ly away.   But, imagine what it must have looked like to see this star in its final death throws as it passed the black hole for the last time…

Till next time,

RC Davison

We are often so amazed by the colorful images we see of nebulae, galaxies and other deep space objects that we may sometimes forget that these colors are not the natural colors, or at least not the colors we would see if viewed directly by the naked eye.

Part of the reason to color these objects so dramatically is to distinguish the different components of the object. That might be different elements or molecules, densities of matter or different energy levels, say from x-rays to infrared to gamma rays.

It really all comes down to the energy of the photons that the CCDs (use to be photographic film) receive. Typically these images are in black and white and are obtained by passing the light from the object through filters, which allow only certain frequencies or energies of electromagnetic radiation to reach the detector. Below are three images of the Eagle Nebula taken (from left to right) in the green, red and deep red parts of the visible spectrum:

You can see some subtle differences in the structure. Interesting, but not too exciting. But, if we assign colors to these filtered images so that the green light emitted by the doubly-ionized oxygen is blue, the red light from hydrogen is green and the deep red light from ionized sulfur is red. This helps to distinguish sulfur from hydrogen, which otherwise would both look red.

This is beginning to look a bit more interesting! Now, by blending these images into one we get the final product:

These color choices show the bluish background of hydrogen and oxygen atoms surrounding the columns of dust and gas containing sulfur. Pretty to the eye and much more informative as to the components that make up the nebula.

These images come from a NASA site “Behind the Pictures”. Check it out. It won’t take long to go through the different pages that talk about using color as a tool, filters and the shapes of the images. There are also many more examples of how this process is applied to learn more about these amazing celestial objects.

Till next time,

RC Davison

The European Southern Observatory has delivered one of the most beautiful images of the Orion Nebula that I’ve seen.

Using their 2.2 meter telescope at the Silia Observatory in Chile, with a series of 5 different filters, the image is close to what one would observe with the naked eye.  But, one needs to remember that the CCDs can collect photons of light over time and build up an image that we humans would not be able to see with the physiology of our eyes.  We wouldn’t be able to see the delicate gossamer structure with the subtle color changes that the CCD can.  So enjoy this beautiful image on your computer!

Orion is riding high in the cold winter night sky and one can easily see the Orion Nebula just below the belt of Orion on the constellation’s left side, as can be seen below.

Orion harbors many wonders, including the red supergiant Betelgeuse marking his upper right shoulder and Rigel, a blue supergiant that marks Orion’s left foot.  Betelgeuse is so large that if placed at the center of our Solar System it would extend beyond Mars and the asteroid belt!  Another jewel that lies within the constellation is the Horsehead nebula, located near the left-most star making up Orion’s belt.

Horsehead Nebula in Orion - Wikimedia Commons

Next time you’re out and about at night, check out Orion, and if you have a pair of binoculars or a telescope available, take some time to check out the jewels that lie within the Orion constellation.

Till next time,

RC Davison