11. August 2011 by RC Davison.

    The Hubble Space Telescope has taken a fascinating image of a planetary nebula known as the Necklace Nebula.

    Planetary nebula are the remains of a star like our Sun as it goes through the final stages of its life expanding and blowing off its outer layers.  The bright blobs embedded in the nebula are areas of gas that are energized by ultraviolet light from the star at the center.  The blue-green color of the nebula reflects the hydrogen and oxygen present, with red indicating nitrogen.  The Necklace Nebula lies about 15,000 light years from us and is located in the constellation Sagitta.

It’s interesting to compare this planetary nebula with the remains of the supernova 1987a:

     Another piece of cosmic jewelry, but one made from a very different process and from a star that was much larger than our Sun. The supernova is the foundry that produces all the heavy metals we have today, from the iron in the hemoglobin of your red blood cells to the gold and silver in the jewelry you may be wearing right now.

     Both of these nebulae are still evolving, and as time passes they will continue to evolve into new shapes, and eventually (10s to 100s of thousands of years) they will fade from view.  But, their remains will fuel the next generation of stars and planets in the cosmos.

Till next time,

RC Davison

Posted in Cosmology, Astronomy | No Comments »

1. May 2011 by RC Davison.

     Two items of interest popped up last week:

First:  The European Space Agency posted a very nice video showing the Andromeda Galaxy in light from X-rays to gamma rays.  About a third of the way into the video, one can see variable stars pulsing and other stars flashing as they go nova, thanks to the view from the XMM-Newton X-ray telescope. Check out “Andromeda’s coat of many colours“.  (Check out the post on 6, January 2011 under the galaxy category for more information about Andromeda.)

Second:  An image posted on the Astronomy Picture of the Day site by Juergen Michelberger shows in very unique detail how stars and planets are affected by Earth’s atmosphere.  Or, more appropriately, why stars twinkle and planets don’t.

     The star, being much further away from Earth than the planet Mars, presents an image that is much smaller in diameter than Mars.  This smaller point of light is affected by the variations of the Earth’s atmosphere due to temperature and moisture much more so than the larger source of light from the planet.  Consequently, the star’s image is randomly refracted, causing it to vary in color and brightness, while Mars shines on steadily over the ten second exposure.  The intricate image is due the camera being swung about.  Check out the link to APOD above for more information about this unique image.

Till next time,

RC Davison

Posted in Astronomy, galaxy | 2 Comments »

10. April 2011 by RC Davison.

     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

Posted in Astronomy | 1 Comment »

9. February 2011 by 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

Posted in Astronomy | No Comments »

24. January 2011 by 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.

     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

Posted in Astronomy | No Comments »

5. January 2011 by RC Davison.

     The power of using infrared light to peer through the dust in the cosmos is clearly demonstrated in this stunning image of the Lagoon Nebula (M8) from the European Southern Observatory’s (ESO) VISTA telescope at the Paranal Observatory in Chile.

     The top view shows a vast field of stars, many of which are cool red stars, but it is the hot young stars that radiate prodigiously in the ultraviolet that help the Lagoon nebula glow in the visible range as seen in the bottom view.

Here is a nice video that fades from visual to infrared views of the Lagoon nebula.

Check out some larger images and more information at ESO’s website…

Till next time,

RC Davison

facebook

Posted in Astronomy | No Comments »

15. December 2010 by RC Davison.

     This delicate bubble is the remnant of a supernova, SNR 0509-67.5, which is located in the Largel Magellanic Cloud, about 160,000 light-years from Earth.

Source: Hubblesite.org

The nebula is about 23 light-years across and is expanding at more than 11 million miles per hour.  The image was provided by Hubble and augmented below with data from the Chandra X-ray observatory.  The blue and green gossamer structure in the center is material heated by the expanding shock-wave of the supernova, which occurred almost 400 years ago.

Source: Hubblesite.org

See the Hubble site for more information and images.

Till next time,

RC Davison

Posted in Astronomy | No Comments »

4. December 2010 by RC Davison.

Pop quiz!  What’s the closest galaxy to our Milky Way?

            Nope! It’s not Andromeda.  And, it is not the Large or the Small Magellanic Clouds. (Which all those who live in the Southern Hemisphere get to see!)

            The closest galaxy to ours is the irregular dwarf galaxy Canis Major, which is about 42,000 light-years from the center of the Milky Way.  The galaxy was only discovered in 2003, as it is obscured by dust and gas that lays within the Milky Way.  Andromeda (M31) is about 2.5 million light years away from us, which makes it the 35^th most distant galaxy from the Milky Way.  Andromeda is the closest spiral galaxy to the Milky Way.  

            The Andromeda galaxy has the distinction of the being the largest galaxy in our gravitationally bound local group of about 40 galaxies.  It’s about twice as big as Milky Way, and that places our galaxy as the second largest in the group, followed by Triangulum (M33), a beautiful spiral galaxy that is possibly a satellite galaxy of Andromeda.

Till next time,

 RC Davison

Posted in Astronomy, galaxy | No Comments »

2. December 2010 by RC Davison.

            NASA’s press conference today (December 2, 2010) revealed that there is a bacteria that can use arsenic instead of phosphorous to survive.  Phosphorus is one of the  six basic elements required for “life as we know it”—the others being, carbon, hydrogen, oxygen, nitrogen, and sulfur. This expands the opportunities for finding life elsewhere in the Universe. 

            When you couple the information about these unique bacteria with the news release from Yale’s Professor Pieter van Dokkum that there are probably three times as many stars (300 sextillion!!) in the universe than previously thought, you have a whole lot of opportunities for life in the cosmos!  This announcement is about red dwarf stars, which are smaller and cooler than our Sun and have extremely long life times because they use their hydrogen fuel at such a slow rate.

            One last bit of information that came out this week is from the European Southern Observatory.  Astronomers were able to analyze the atmosphere of a “super-Earth” GJ 1214b, as it passed in front of its parent star GJ1214.  The results showed that the planet has an atmosphere mostly made of water in the form of steam or at the very least it is dominated by thick clouds or haze.  This was gleaned from a planet that is over 40 light-years from us and orbits its star every 38 hours at a distance of about 2 million kilometers.  (Note that we are about 150 million km from our Sun.)

            To summarize this week’s events: We’ve got a form of life on Earth that lives off an element that is poisonous to most life on our planet; three times as many stars that may have planets in the Universe; extrasolar planets that have water vapor in their atmospheres.  Sounds to me like the odds for extraterrestrial life is getting better and better!

            It’s about time that ET phones our home!

 Till next time,

 RC Davison

Posted in Astronomy | 1 Comment »

5. November 2010 by RC Davison.

      NASA’s EPOXI mission, formerly the Deep Impact mission that launched an impactor into comet Temple 1 on July 4, 2005, has just sent back some amazing images of the nucleus of comet Hartley 2 as it flew by at a distance of about 700 km or about 420 miles.

       You can easily see the jets of vapor being back-lit by the Sun at the ends of the nucleus, which is about 2 km, or about 1.2 miles long.  This is a great image that shows just where the large tail and coma, which surrounds the nucleus comes from.  Check out NASA’s site for EPOXI for more pictures and information.

This isn’t the first time we’ve gotten an image of a comet’s nucleus.  The picture below shows a nice comparison of the five comets we’ve peeked at.

 Till next time,

RC Davison

Posted in Solar System, Astronomy | No Comments »