Author: Allan Hall

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Basic spectral classes finished, plus a couple extra!

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Stars are classified into spectral classes, of which there are seven basic classes and several more esoteric ones. The seven basics are O, B, A, F, G, K and M and they are shown here along with a few others:

 

The other classes show are C for Carbon stars (very old stars that are burning out), S (late type giants) and W which are the most interesting of them all, Wolf-Rayet which are massive stars with howling solar winds. If I do absolutely nothing else with spectroscopy it has been a huge success in teaching me more about stars and the wild variety of them out in the universe.


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2012 Venus transit from Smithville Texas

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I hope you got to see the 2012 Venus transit because most likely no one you know will still be alive when the next one happens. My wife and I went over to just outside Smithville with a couple other members of the Huntsville Amateur Astronomy Society and set up to image the event.

Setup for 2012 Venus transit I set up my main scope, a camera with a 300mm lens and of course a pair of binoculars to watch with. It started out pretty cloudy and never really improved, we did however get lucky enough to have many breaks in the cloud cover to get some awesome views.

Plane crosses sun during 2012 Venus transit The above is a composite of many images to show the movement of Venus across the surface of the sun, and yes, there is an airplane there as well! After some serious research, and a lot of help from Steven at Austin-Bergstrom airport, I am fairly confident we have identified the aircraft in the photo. Keep in mind that this is not a definitive ID as we obviously can not see the tail number for a positive ID. Based off radar information from the airport there is a high probability this is Delta flight 1005, tail number N335NB. The plane is an Airbus A319 aircraft that was leaving Austin-Bergstrom airport at approximately 19:55 (7:55pm) CDT. At the time the image was taken the aircraft was climbing past 2000ft at just over 200kts just starting a turn to its right to head for its destination of Minneapolis. To make the image even more interesting, the airport was approximately 40 miles away (direct line, not road miles) at a heading of 287 degrees and the sun was just below 17 degrees above the horizon. Lastly, I mentioned that I also had a camera there which was using Baader solar film, here is an image from that setup:

2012 Venus transit with different camera The 2012 Venus transit was amazing. The weather forecast said I should not have been able to see it, much less image it. I have never been so happy the weather guy was wrong!


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Annular solar eclipse from Albuquerque, NM

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My wife and I decided to travel to Albuquerque New Mexico for the annular solar eclipse on May 20th, 2012. An annular solar eclipse is where the moon comes directly between the sun and our little earth but isn’t close enough to the Earth to completely block out the sun. We choose that Albuquerque because it was far enough west to see the complete annular part of the eclipse and was directly on the center line where the moon would be exactly in the center. Here are some compilations of the images I took while there:

poster created from images taken during the annular solar eclipse

Collage of images taken during the annular solar eclipseI had two cameras on my main telescope and mount. The first was a Nikon D7000 mounted via prime focus shooting through the telescope and a Thousand Oaks glass filter. The second camera was a Nikon D90 mounted on the side of the telescope shooting through a Nikon 70-300ED-IF lens covered with a homemade filter using Baader solar film.

We also observed the solar eclipse through solar film and protected binoculars.

While not my first experience viewing a solar eclipse, my last experience was probably almost forty years ago. Although I do remember the experience as a small child, this was much more rewarding. If you get the chance to experience a solar eclipse of any kind I urge you to take some time off and go enjoy it.

While in the area, no astronomy buff would dare leave before seeing the National Radio Astronomy Observatory, also know as the Very Large Array or VLA. This has been included in many movies such as Contact, Terminator Salvation and Interstellar and is an absolutely awesome place to visit.

closeup of the side of a radio telescope

The pictures do not really convey how amazing, or huge this place is. Each dish in the Very Large Array are twenty five meters across, or over eighty feet. That would be impressive alone however there are twenty seven of these dishes on rails similar to a railroad track. Each arm in the huge Y pattern of the tracks is approximately thirteen miles long. This distance between the telescopes is why it is called the Very Large Array.

An array of radio telescopesThey have a great visitor area and unbelievably allow you to roam around the area way more than I had expected. Tours are even given at certain times although there were none while we were there and since we were in transit when we stopped here we could not stay as long as I would have liked. If you get the chance, it is a fantastic place to visit.

More information on the Very Large Array can be found on their website.

I hope you enjoyed the images of the solar eclipse and very large array!  


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New spectroscopy software Rspec, and Arcturus revisited

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My first foray into spectroscopy was barely a month ago and already I am shifting gears. It turns out it is pretty straight forward to image the spectra of stars, but processing it and making something of the image is another story entirely.

Like a lot of people I would imagine, I started using a program called Vspec, mainly because it was free and also because there are a lot of people using it. The problem I ran into rather quickly was that if you are starting from scratch and understand nothing about the spectrum, the software or the entire theory of spectroscopy then Vspec can be a bear to figure out.

So I broke down and ordered Rspec from the same guy I bought the Star Analyser 100 from and man did that make my life easier. In just a few days I went from things I knew were wrong but had no idea how to fix to this:

 

Which not only am I fairly sure has some semblance of being correct, but I actually understand some of! Interesting things about this profile include the 5850-5900 range showing sodium and calcium absorption lines, 5160-5180 showing a large concentration of magnesium lines, lines just before and just after 5400 showing iron and the dark lines just before 4300 showing CH or methane.

Now admittedly I looked up the spectrum in a reference book and got the information for the spectral lines from that book, but the cool part about it is I could actually see what they were talking about and their observations matched my images and curves. So either I am getting more correct in my image taking and processing, or more delusional in my old age, either of which works for me 🙂


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Dark nebula Clark 549, something different

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Most of the astrophotography you see has a common theme, beautifully colored and highly detailed images of some nebula or galaxy somewhere, unlike Clark 549. People don’t shoot the stuff without tons of detail and/or colors. Shame really. Here is an image of a dark nebula, or a nebula that is dark (duh!). The only way you see it is because you can see where it blocks the stars behind it.

a dark nebula  

This example of dark nebula is Barnard 143, or Clark 549, or as I refer to it, the Lyre Nebula (I hope you can see why). I have shot this image before in October of last year but it really did not do it justice. I am not sure this image does either but it certainly conveys more of the feeling I wanted to with this target so here it is. Sometimes it isn’t what you see, but what you don’t see that is interesting.

I am sure this will continue to be a favorite target of mine as I try to get the dark dust lanes to stand out more. You can see some wonderful dust lanes in my images of the Orion Nebula for example. If I stretch the image far too much I can see the start of the dust lanes jumping out. Maybe when I get a CCD and get really good with it I can make this a priority target. I have a feeling that a mono CCD will really bring those details to life. Unfortunately the mono may increase detail, but it will lose those wonderful blue and yellow stars surrounding the dust lanes.

I plan on checking out many more of these nebulae in the future. Stay tuned to hopefully see many more images of these kinds of targets.

You can find out more about a dark nebula such as Clark 549 at Wikipedia.


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Stellar spectroscopy, the light of the stars

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Stellar spectroscopy is a really interesting field, and since I have never been content on doing one thing and always being fascinated by things I don’t understand I decided to look into it. Stellar spectroscopy is the study of the spectrum of light being emitted or reflected by an object in space. This can tell you a lot of things, for example what the chemical makeup of a star is (which tells you the star type), or the speed at which an object is moving towards or away from you. My primary reason for wanting to look into this is to learn more about the stars themselves instead of just imaging them. In my mind spectroscopy and stars seem to naturally go together. To this end I ordered a Star Analyser 100 from Rspec Astro, great guy to deal with, you can visit his website at http://www.rspec-astro.com. Once I received the grating filter I have to try and figure out how to use it, so I made an exposure chart to see what the spectral lines (or stellar lines) look like. This is the stellar spectra of Arcturus:

Stellar spectroscopy

Stellar Spectroscopy and star types

There are many different types of stars. Each star type or stellar classification can be determined through spectral analysis. As light passes through the filter a specific pattern of light emerges, including bands of darkness called absorption lines. Reading these patterns and comparing them to the known star types allows someone to identify the type of an unknown star.

All the different types of stars fit into seven basic classifications of typical stars, and a few more for stranger types which we believe are far less common. As I learn more about stars I plan on being able to come to my on conclusion about what type of a star my target is, and then compare it to what the real scientists say. Hopefully I will be able to match my results with theirs. Even if I don’t start off that way, it should be a lot of fun learning stellar spectroscopy!


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My first serious planet attempt, Saturn

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Saturn is probably the single most imaged planet, besides Earth of course. The rings are just mesmerizing. Imaging planets is a lot different than my normal fare of DSOs, it uses a video camera instead of a normal DSLR/CCD. Because of the unsteady air and extreme magnification you have to take thousands of images and stack them keeping the best parts of each and discarding the rest. The result, can be very nice:

 

I bought an Orion Starshoot Solar System Imager IV for about $99 just for this and am using a Celestron CPC 1100 XLT 11 inch SCT at about 2800mm focal length with a 2x barlow. The magnification of this scope is nice but man, what a pain in the rear to use compared to my refractors!


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