within-season changes in the periods and light curves of w uma binaries russ genet orion observatory...
TRANSCRIPT
![Page 1: Within-Season Changes in the Periods and Light Curves of W UMa Binaries Russ Genet Orion Observatory Tom Smith Dark Ridge Observatory Dirk Terrell Southwest](https://reader035.vdocument.in/reader035/viewer/2022062519/5697bfb61a28abf838c9e302/html5/thumbnails/1.jpg)
Within-Season Changes in the Periodsand Light Curves of W UMa Binaries
Russ Genet Orion Observatory
Tom Smith Dark Ridge Observatory
Dirk Terrell Southwest Research Institute
The 94th Spr9ing Meeting of the AAVSOMarch 25-26, 2005, Las Cruces, New Mexico
Presented at
Acknowledgment for support fromErick Sturm and Ray Weymann
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•Common envelope with mass and luminosity transfer between the two stars
•Convective (W UMa) and Radiative Envelopes
•Tend to have period and light curve variability
Overcontact Binaries
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W UMa Systems
OC Systems with convective envelopes are the W UMa systems
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Early-type Systems
OC Systems with radiative envelopes do exist, e.g. TU Mus
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Planets?
W UMa systems have several characteristics that make them favorable for the development of habitable planetary systems.
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Light Curve Variability
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Inexpensive Equipment• Meade 10” LX200
• SBIG ST-7XE CCD
• UBVRCIC Filter Set
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The Wilson-Devinney Program• First published in 1971 by Bob Wilson and Ed Devinney
• Still being developed. New version uses filter bandpasses rather than effective wavelengths. Adds Kurucz atmospheres.
• Uses modified Roche model to compute figures of the stars. Can model stars with eccentric orbits and non-synchronous rotation.
• Can do light curves, radial velocity curves and spectral line profiles. Unpublished versions have added ability to model polarization curves, fluorescence and X-ray pulses.
• Consists of two programs:
• LC computes light curves given a set of parameters
• DC fits light curves to observations using the method of differential corrections
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Program Objectives
Looking for subtle changes in light curve shapes and eclipse timing
* Within season * Between seasons
Light curve shape changes could be due to
* Starspots * Bright steaming * Observational errors
Eclipse timing changes could be due to
* AML * Applegate * Micro MT episodes * Third bodies *Obs error
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Program Approach
Make lots of observations
Worry precision, both timing and photometric
Taylor analysis to the situation
Learn and refine
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Make Lots of Observations
Total Dedication Multiple Observatories
Binaries * Few * Short period * North * Strategy
Maximize Observing Time * Nightly (airmass) * Seasonal (dew)
Semi-Automation * Observations * Reduction * Analysis
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Binary DRO Orion Total
V523 Cas 31 15 46 RW Com 18 8 26V400 Lyr 7 10 17TZ Boo 18 13 31V1191 Cyg 22 39 61GM Dra 14 3 17
Totals 110 88 198
~Obs/Night x640 x320
~Total Obs 70K + 28K = 98K
Pilot Season Observations
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RW Com (20040508) Rc (JD:2453134)
10.400
10.500
10.600
10.700
10.800
10.900
11.000
11.100
11.200
11.300
11.400
Julian Date
Inst
rum
ent
Mag
nit
ud
e
-0.400
-0.300
-0.200
-0.100
0.000
0.100
0.200
0.300
0.400
0.500
0.600
C-K
Ph
oto
met
ry
C-V(meas) + C Known
C-K
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V400Lyr (20040808) Rc
2.800
2.900
3.000
3.100
3.200
3.300
3.400
3.500
3.600
3.700
3.800
3.900
4.000
JD: 2453226
Inst
rum
ent
Mag
nit
ud
e
-0.970
-0.870
-0.770
-0.670
-0.570
-0.470
-0.370
-0.270
-0.170
-0.070
0.030
0.130
0.230
0.330
0.430
0.530
0.630
C-K
C-V(meas) + C Known
C-K
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V523Cas (20040912) Rc
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
1.100
1.200
1.300
1.400
HJD: 2453261
Inst
rum
ent
Mag
nit
ud
e
-0.270
-0.170
-0.070
0.030
0.130
0.230
0.330
0.430
0.530
0.630
0.730
0.830
0.930
C-K
C-V(meas) + C Known
C-K
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Make Lots of Observations
Total Dedication Multiple Observatories
Binaries * Few * Short period * North * Strategy
Maximize Observing Time * Nightly (airmass) * Seasonal (dew)
Semi-Automation * Observations * Reduction * Analysis
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Worry Precision
Timing Precision Clock / time recorded Shutter Barycentric correction
Photometric Precision Model (Howell + Young) Brightness (program & comps) Same position / instrument Flats, transformations Guiding, defocus, dither
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Aperture Experiment
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Erick Sturm Cal Poly
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Taylor Analysis
Light Curve Shapes Parametric / nonparametric Simple statistics / entire curves Smoothing / point by point Single nights / grouped nights
Eclipse Timing Errors (internal / external) Minimize seasonal scatter Interactions / Cuts Part curve / whole curve Hertzsprung method Sliding whole-curve fits Master curves / Tsesevich Seasonal ephemeredes
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Hertzsprung Method
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Folded Data Results
8.931
8.932
8.933
8.934
8.935
8.936
8.937
8.938
8.939
8.94
0.86 0.88 0.9 0.92 0.94 0.96 0.98
Miliphase
Relat
ive M
agni
tude
Series1
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O-C Combined Data OO and DRO
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
10.00
15.00
20.00
25.00
0 100 200 300 400 500 600
Orbital Cycles
O-C
(S
eco
nd
s)
=
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O-C Combined Data OO and DRO
-30.00
-20.00
-10.00
0.00
10.00
20.00
0 100 200 300 400 500 600
Orbital Cycles
O-C
(S
eco
nd
s)
=
Number of Points 32Standard Deviation 4.3 secStd Error of Mean 0.8 sec
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Learn and Refine
Lots of Observations Aperture Simultaneous color bands More complete automation Precision Aperture Simultaneous color bands Various refinements
Analysis
Feedback
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MTT
Multiple Tube Telescopes
B
V
R I
U BV
c
R
I
Four Shooter Five Banger
c
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Two-Channel Dichroic
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Four Color
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Observations this past season 98K
Observations this coming season8 months * 20 obs/month * 2 observatories = 320 nights320 (Orion) +640 (Dark Ridge) = 1000 obs/night320 nights * 1000 obs / night = 320K ObsSay 180K obs 2005 seasonIf 3 binaries, then 60K obs/binary
10” to 20” x 41 filt to 2 filt x 2
14” to 20” x21 filt to 2 filt x 2
2.5 K obs/night eachTotal of 5K obs/night320 nights/season1.6Meg obs/seasonIf 3 binaries, then533K obs/binary/season
Potential Throughput
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32 nights = 15K observationsYielded 0.8 sec SD
533K obs possible 2 ea .5-m 2 flts533K/15K = 34.7Sqrt 34.7 = 5.8
0.8/5.8 = 0.14 sec
If ensemble *2 then Sqrt 2 factor0.14/Sqrt2 = 0.1 sec
If 4 instead of 20.1/Sqrt2 = 0.07 sec
Potential Precision
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Learn and Refine
Lots of Observations Aperture Simultaneous color bands More complete automation Precision Aperture Simultaneous color bands Various refinements
Analysis
Feedback