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7/12/2009

July 9th &10th Observations; Light Shields and Carbon Stars

Well the last month or so has been very interesting. I have only had a couple of nights of observing as the weather in Utah this year is not what it usually is. Winter is by far my favorite season for observing as when there isn't a storm the quality of the air is such that I think I get my best observing in. However, with summer I usually count on getting at least one session a week in but not this year.

I do have an observation from June 27th and June 28th to post but that information in on my MacBook Pro that had its display replaced under warranty. I'll get that information and my sketches and post that up tomorrow when I get the laptop back.

I did get an observation in on July9th and July 10th. The moon was in the first day of its waning gibbous stage so any major plan to see deep sky objects was not feasible. I got out and using the XT10 tonight ( just so everyone knows, I use either an XT8, XT10 or a 15 inch Obsession once I get the final parts in that it needs; I bought it used and got a good deal but part of that is I needed to order a few replacement parts. The price I paid with the replacement parts is still far less than a new one and the mirror itself is in excellent condition). I will state which scope I used for each session from now on. Also right now I use either the Orion Stratus EP's or the B. Hyperion's in my observations though I also own other eyepieces that I won't mention for now.

I set up tonight using all 8 light shields in place and later after the moon had come up, I wondered why I had done that? In June around 2:30a.m. to 3:30a.m. using the shields to keep my dark adaptation I could discern the Milky Way along with hints of dark details from my backyard. Nothing like from what I've seen from a dark site, and very milky and faint, but I have been able to discern it as a fellow observer has verified as well.. So having a pair of light shields helps in terms of keeping one's eyes dark adapted allowing one to see more of what is in the skies around you. This is a link where you can go to and see the instructions for what I used to design my light shields. They are basically the same in construction. Here are some images of mine:

Light Shield Frames






























Light Shield Completed with 14 Mil Plastic Attached



























Now back to the observation for this night. While setting up I saw Vega glowing in brightness as the twilight deepened. Before the moon came up I decided to quickly take a look at M57 which I did. I found it quickly in Lyra and noticed that at 92x the ring shape was evident as was the milky interior of the ring. I noticed at 200x with the 5mm hyperion that the transparency was going to be not so good this night as the image came and went in terms of the details I could discern.

After M57 I prepared to do my double star observing for this night which is the type of observing that I really like doing around a full moon. One thing also that I am going to add is to begin looking at Carbon Stars also. These are stars that are either late red giant stars or sometimes a red dwarf who atmosphere's contain more carbon than oxygen. These two elements combine in the upper atmosphere of the star to make carbon monoxide allowing the remaining carbon atoms to form other carbon compounds and giving the star a really "red" look if you catch it at the right time. A local member of our astronomy board gave me a list that I'll share if you contact me and want to take a look at a few. Or you can go to this link which is from the North Kansas Astronomical Society. T Lyra is the one I'm going after this week. Nice red contrast I've been told. In the S&T Sky Pocket Atlas you can identify a carbon star by the a (c) next to an open ring for the star location.

I haven't scanned my actual sketches from my double stars so I used them to create a digital sketch in GIMP. I'll post them as an edit tomorrow or Tuesday. So my first double that night, July 9, 2009 at 10:59p.m. was Graffius or Beta Scorpii, or also known as Acrab, Akrab or Elacrab. The primary is a large white star in the 5mm Hyperion I used that night on all of the doubles. The secondary was smaller and a very faint blue in color. The separation is 14 arc seconds. I split this double easily at 57x, 92x and 200x.
Here is the sketch:





















My next observation was of Al Niyat Sigma. I used the XT10 with the 5mm Hyperion at 200x to make this observation. The primary is a very bright, to the point where if one is rushing they could fail to observe the companion which is west-southwest of the primary. The primary in the EP was white while the companion was a faint white with a bluish tint. You can find details about this star at this link by Jim Kaler at Stars. Here is the sketch.



















My next double/multiple star system that I observed was Delta Serpentis or Qin/Chin by its other two names. There are four stars, or two binaries in this system that are roughly 210 light years (ly) from Earth, while the pair of binaries are 66 arc seconds apart.

The two visible that I drew are F stars that are yellow white subgiants, but I saw them as white for the primary and white with a bluish hue on the companion. They are 4 arc seconds apart and orbit each other every 3200 years. My observing notes state that these are a very, very close double that I barely split at 200x, and had to bring out my 2x barlow to get a better view of the split at 400x. Transparency though didn't allow for a lot of clears views of this double at 400x.






















My next observation was of Delta Herculis or Sarin, located just south of the keystone of Hercules. This multiple star system/"double" was the most interesting to me because of what it is. The primary here seems to be a large white class A (A3) star but it isn't. It is actually made of two vibrant, fairly youthful, hydrogen-fusing dwarf stars. The two are called Delta Her Aa and Ab are not visible in amateur scopes since you need a "sophisticated interferometer to split them."
From this site we learn the following:

"Delta Her Aa, the brighter, at near-fourth magnitude (3.49), radiates the light of 18.5 Suns from its 8500 Kelvin surface, which gives a radius of 2.0 times that of the Sun. With a projected equatorial rotation velocity of 270 kilometers per second, the star really whizzes around, its rotation period under nine hours. Luminosity and temperature -- plus theory -- give a mass of 2.0 Suns and an age of 370 million years, only about a third of its hydrogen-fusing lifetime. We have to do some guessing about the companion, Delta Her Ab. From its absolute visual brightness, it is probably a class F (F0) dwarf with a temperature of 7500 Kelvin, a luminosity of 6.8 Suns, a radius of 1.5 solar, and a lower mass of 1.6 solar. A physical separation between Aa and Ab of at least 1.45 Astronomical Units, together with the sum of masses, yields a period of at least 335 days."

Here is my sketch. Interesting looking at it and thinking what the large white primary really represents. Please go to the link for information on the other 3 stars in this system.




















Well, my next one will be Xi Scorpii and few more doubles/multiples and then returned to DSO's. I will post my June 28th observations tomorrow.

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