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

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5. April 2011 by RC Davison.

     There are jewels in the night sky and some of them are more fanciful than others. The spiral galaxy NGC 4921 is a case in point. Please click on the following links in the article for much higher resolution images. (Click for a larger image.)

      This beautiful barred-spiral galaxy resembles more a ghostly cosmic jelly fish than the typical spiral galaxy you may think of like the Whirlpool galaxy (M101) below:

     You’ll notice immediately that NGC 4921 is missing the well defined spiral arms seen in the Whirlpool. There is structure there, but it is much more subtle.  You do see a dark swirl of dust around the core, accented with bright blue stars that are forming along this band.  And, you can see the bar that extends across the nucleus of the galaxy as well as some spiral structure to the arms.

     To me, what is most remarkable about this galaxy is that the white gossamer cloud is not dust but stars – billions and billions of unresolved stars spread very uniformly around the galaxy.  In a well defined spiral galaxy we don’t get the same impression of the vast number of stars contained within because they are clumped together in the arms.  NGC 4921 and the Whirlpool galaxies are roughly the same size (about 200,000 lightyears verses 175,000 lightyears across), so comparing the two galaxies gives a good sense of how many stars are condensed into the arms.  It is interesting that this type of galaxy is termed an “anaemic spiral” because of the uniform distribution of stars.

      The galaxy is located about 320 million lightyears away in the galaxy cluster known as the Coma Cluster or alternatively Abell 1656 in the constellation Coma Berenices.  If you look closely at the image you will see thousands of galaxies scattered about NGC 4921 and even behind the nebulous galaxy.  Some are part of the Coma Cluster, while others extend much further beyond it.  This annotated image below (Click for a larger image.) shows highlights some of the details contained in this amazing image.

     Check out the Hubble website for more information, images and several short videos that will give you more in-depth information about this beautiful jewel of the night sky.   Enjoy the wonders of the Cosmos!

Till next time,

RC Davison

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6. January 2011 by RC Davison.

     The Andromeda galaxy is one of my favorite galaxies, so the latest images from the European Space Agency (ESA) are a real treat.  Using the Hershel observatory to take Andromeda’s portrait in the infrared and the XMM-Newton X-ray observatory to capture the galaxy’s image in the high energy spectrum, ESA has produced a composite image that shows the star birthing and dying regions of the galaxy in the highest resolution to date.

      The top right image show the galaxy in the infrared as taken by Hershel.  This shows the regions of the galaxy where there are concentrations of dust that harbor the development and birth of stars.  The image at the lower right shows the regions hot with X-rays, which is indicative of gas being heated to extremely high temperatures from the shockwaves produced when stars meet their end as novas and supernovas. X-rays can also be generated as one star pulls material from another in a binary pair.  This gas is heated to high temperatures as it is accelerated in its fall to the parasite star.

     The image also shows a high concentration of X-rays at the center of the galaxy, which is to be expected because of the high density of stars there and the resident supermassive black hole that resides at the core of the galaxy. If you look closely at the X-ray image there appears to be a bubble surrounding the core of the galaxy.  Possibly a shockwave propagating outward from the core, indicating a more active period of the galaxy’s massive black hole. Be sure to check the links to see the all the detail in these great high-resolution images.

     Take a look at ESA’s website for more information on these new images of Andromeda.

Till next time,

RC Davison

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28. December 2010 by RC Davison.

     In the last post (It’s Full of Galaxies) we saw an infrared image from the Herschel space telescope looking at a tiny piece of the cosmos revealing thousands of galaxies 10 - 12 billion light-years from us.  The image below is also an infrared image, but it is a view of millions of galaxies as taken by the 2MASS (Two Micron All Sky Survey) looking across the night sky.

      The blue band in the image comes from the stars in our own galaxy.  Note that the distribution of galaxies is not uniform, as one might expect but there are clusters, strings and webs of galaxies.  These structures are remnants of the big bang and the gravitational attraction between matter and the mysterious dark matter.  Think about this:  All of the matter we can see and account for in the Universe only adds up to about 4-5% of the total mass of the Universe!

     The  2MASS survey was conducted using two 1.3 meter telescopes, one in Arizona and the other in Chile, imaging the sky at 3 separate frequencies in the near infrared.  Imagine what this would look like if we were able to use telescopes in space that are above the filtering effects of our atmosphere in the infrared.

      Check these links for more information and a larger image.

Till next time,

RC Davison

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24. December 2010 by RC Davison.

      These are not stars but galaxies, thousands and thousands of them and each one containing billions of stars.  This snapshot from the Herschel infrared space telescope shows galaxies that are 10-12 billion years old with the red ones being the most distant.  The white  ones indicate galaxies with the greatest star formation.  Looking closely at the image one does not see an even distribution of dots/galaxies, which indicates that some of these galaxies were forming in clusters at that time.

     This image was one taken as part of the Herschel Multi-tiered Extragalactic Survey (HerMES) Key Project.  The purpose of the project is to study the evolution of galaxies in the distant cosmos.  This particular image lies in a region of space called the Lockman Hole, which is in the constellation of Ursa Major and provides a relatively unobstructed view into a far corner of the Universe.

     The next night you are out, take a look up into the night sky and think about the fact that all you can see is in the optical region of the spectrum.  Consider what lies beyond our narrow view of the vast cosmos.

Till next time,

RC Davison

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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

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25. October 2010 by RC Davison.

“Inside The Milky Way” is a new production by the National Geographic Channel that aired Sunday night and will be broadcast again on Thursday, October 28th at 9 pm.  I saw most of the program and highly recommend it.

Stunning visuals, animations, and the latest hot topics in astronomy are intelligently discussed in this 2-hour program.  Black holes, dark matter, galactic superclusters, and the Andromeda/Milky Way collision (In about 2 billion years - don’t sweat it!) are some of the topics covered.  (Just ignore the sound effects for the supernova!)

Check out the web site for some videos and photos.  Enjoy!

Till next time,

RC Davison

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9. October 2010 by RC Davison.

     Initially, I was just going to put up a link to the European Southern Observatory’s list of top 100 images, which has enough pictures to keep any fan of the cosmos happy.  But, I made the mistake of checking out NASA’s Hubble site, which has a huge collection of images, and I compounded that mistake by looking at the European Space Agency’s (ESA) site for Hubble.  Wow!  I think I’ve overloaded my neural-net!

There is just way too much to look at on these sites!  As a tantalizing tidbit, take a look at this beautiful Hubble image of the spiral galaxy NGC 5866 seen edge on.

Click on the link above for larger images (down-loadable) where you can enjoy the exquisite detail Hubble captured of this galaxy.

One last thing.  ESO is running a contest - ESO’s Hidden Treasures for anyone that has an interest in creating a new image from their data archives.  They provide instructions on what you have to do to create the image, but hurry, the contest ends on November 30, 2010.

Till next time,

RC Davison

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22. September 2010 by RC Davison.

     If you’ve got a few minutes check out the European Space Observatory site and specifically this link, which shows the difference between what we see in the visual part of the spectrum, versus the infrared part of the spectrum in a 38 second movie.

     There is great interest in the barred spiral galaxies because it is believed that our Milky Way is also a barred spiral.  NGC 1365 is about 200,000 light years across, which makes it about twice as big as our home galaxy.  This galaxy is about 60 million light years from us and is part of the Fornax galaxy cluster.

If you’ve got a few minutes, check out the site.  As you’re gazing at this incredible island of stars, think about how many planets may orbit the 400 billion or so stars in this galaxy, and of those, how many may have life looking back at us in equal awe and wonder…

Till next time,

RC Davison

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