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Primary Imaging System

The mount is a Losmandy GM-8/Gemini 2 with a Losmandy G-11 tripod.

​Photons are collected with an Orion 200mm Ritchey Chretien telescope. A two inch Feathertouch focuser replaces the stock Crayford focuser.

Guiding is done with a Stellarvue 60mm/2 inch straight through focuser and the SBIG ST-i autoguider.

Imaging is done with SBIG ST-402ME with a BVIR filter wheel and focal reducer.

​Anyplace PC software allows basement PC to control two netbooks that control the above hardware.
Background

Stars are luminous balls of gas held in equilibrium by two forces operating in opposing directions - gravitational force directed towards the center of mass of the star, and radiation pressure from the nuclear fusion process directed from the core toward the surface of the star.

​Variable stars are stars that change in brightness and are divided into two major groups, extrinsic and intrinsic. Extrinsic variable stars change in brightness. Typically by the eclipse of one star by another. Intrinsic variable stars change in magnitude due to internal physical change that cause them to periodically brighten and fade.  Pulsating variables are one type.​



Hypothesis

My hypothesis is that amateur astronomy equipment and software can produce research quality measurements of variable stars brightness in a suburban back yard.



Scope

This project focuses on an over contact binary star named V0523 Cassieopia (Cas) located at RA = 00h 40m 06.262s and DEC = +50d 14m 15.53sec . V0523 Cas is a W-type (which is just a label) W Ursae Majoris (UMa) eclipsing binary star system. A few facts of V0523 Cas are:
     1. Its orbital time is about 5.6 hours. Which is one of the shortest periods among contact binaries.
     2. Its light curves show a deep eclipse.
     3. The V0523 Cas light curve has a deep magnitude change of 10.6 to 11.45 .


The traits of a W-type W UMa eclipsing binary are:
     1. The smaller star is hotter.
     2. Their Roche lobes (which is a tear drop shape around the star that contains the stars materials) have extended beyond their regions where the star’s
         orbiting material is gravitationally bound to that star’s atmosphere.
     3. The stars have been in contact for a long enough that the stars have come into an almost equal temperature.


Definitions

Astronomy photometry- Photometry is the science of the measurement of light. Astronomy photometry is a process measuring the brightness or intensity of space objects.

Binary star system- A binary star is a star system that has two stars orbiting around a common point in space. One star is called the primary and the other star is called the secondary.

Different types of binary stars- There is visual binary stars which means that to the human eye it looks like a binary star but it really is not one.

The difference between luminosity and brightness- The difference is that luminosity is the amount of light sent out by a star but brightness is the amount of light received.

Mass- Mass is an internal property of an object. How dose mass differ from weight- A example would be, A five pound bag of sugar weighs 5.0 pounds on earth but weighs almost 0.83 pounds on the moon because of the gravity that the Moon puts on the sugar. But, the mass of that five pound bag of sugar is the same whether the sugar is on the earth or on the moon.

Why are eclipsing binary star systems important – Their motion and other facts such as radius, temperature and mass help us to learn about single stars which have very little motion.

Five common types of eclipsing binary systems- There is detached which means there is a big difference in distance from each other. There is semi-detached which means they are exchanging a little material to each other but are not touching each other. There is near contact which means the two stars are almost touching. There is contact which means that the stars are touching and then there is over contact which means that stars materials are overflowing into each other and that their atmospheres are touching.


Method

The laboratory was a suburban backyard and three nights of clear sky with a lot of moonlight. The main equipment used to support collecting the light curve data points were an Losmandy GM-8 equatorial mount with Gemini 2, SBIG ST-402ME camera with B and V filters, Orion Ritchey Chretian 8 inch astrograph telescope, Orion Star Shooter Autoguider( which is attached to the guied scope), and Stellarvue 60mm guidescope. The primary software used to get the light curve data points were Astroplanner V2.0 for determining the best time to take a picture of V0523 Cas on each night, CCDSoft V5.00.210 for camera control, Minor Planet Observers(MPO) Canopus for image reductions and initial data analysis of light curve and Binary Maker 3 for final analysis of light curve.  In summary, the method was to compare BM3 generated data with the suburban backyard measurements.


Results

Figure 1 below shows the physical relationship between the primry and secondary stars of V0523 Cas as per Binary Maker 3 (BM3). BM3 generated this image using data I provided from various sources. V0523 Cas is shown at phase 0.7450 with phase 0.0 representing the time of minimum light.

Figure 1. V0523 Cas Phase Plot Generated by BM3
Figure 2. V0523 Cas Light Curve Generated by BM3
Figure 2 above shows the BM3 light curve created from prior research data from other sources. BM3 shows the varying brightness of the V0523 CAS completes one period (phase) in approximately 5.6 hours.

Figure 3 above shows the measured data. Note that the period of the measured data is approximately 5.609 hours. If one normalizes the y-axis of figure 2 and figure 3, one would conclude that the two figures have very similar maximums and minimums. In summary figure 3 shows three different nights of minimum and maximum light. The light curve data from the different nights is well aligned. The error between previous research data and the data obtained for this project was typically less than 0.01, which is considered very good for photometry.

An assessment and discussion on the velocity of the two stars of V0523 Cas is a complex one and is therefore intentionally not discussed. However, Binary Maker 3 shows that, based on prior research data, the primary is orbiting the common point in space at approximately xx kilometer per second, the secondary is orbiting the commn point in space at xx kilometers per second and that the V0523 is moving at a radial velocity of 2.54 km/sec away from earth.

Figure 3. Measured LightCurve For V0523 Cas
Legend shows month/day of measurements.
Conclusion

The strong correlation between prior research quality data derived by others and my the measured data shows that the hypothesis is true, " Amateur astronomy equipment and software can produce research quality measurements of variable stars brightness in a suburban back yard".

While performing this project I learned or relearned:
     1. Eclipsing binary stars are critical for understanding properties such as mass, velocity and temperature of non-varying stars.
     2. How to use the comparative method to test hypothesis. Compared other researcher data from dark sites  to my data.
     3. How to use error measurement which is critical for reporting results for any topic.

Sources

1. American Association of Variable Star Observers, http://www.aavso.org/variables-what-are-they-why-observe-them, 20 October 2011


2. Southeastern Louisiana, http://www2.selu.edu/Academics/Faculty/rallain/plab194/error.html, 2011


3. Austrailia Telescope Outreach and Education, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometrytop.html, 19 October 2011


4. User Guide for “Binary Maker 3-Light curve Synthesis Program” David H. Bradstreet and David P. Steelman, Eastern University in Norristown PA, 2004, p198-242


5. Undergraduate thesis on “Observations and Models of Eclipsing Binary Systems”, by Jeffrey L. Coughlin, Emory University, Department of Physics, 2007, p1-17