Tables 3.2, 3.3, 3.4, and 3.5 show the best-fit transit parameters and uncer-tainties for the long-term observations obtained by the MCMC analysis. We show the transit light curves and the best-fit models of each observation in Figure 3.1, 3.2, 3.3, and 3.4.
As shown in the figures, the fading shapes of the light curves vary with observational epoch. This is a similar phenomenon to that reported by van Eyken et al. (2012), Yu et al. (2015) and Raetz et al. (2016). To solve the origin of shape changing, we give an independentRp/Rs andbfor each light curve. Additionally, we find “double fading” in one observational epoch on 2014 November 22 (JD 2456984), 2015 January 10 (JD 2457032), and 2015 December 1 (JD 2457358). Double fading events are previously unreported phenomena.
To understand these double fading events, we give the individual fitting parameters for the first and second fading events when double fading events are observed. For example, to fit the first fading event, we remove the data at the second fading in a visual way. We then fit the light curve without the second fading by the transit model. On the other hand, we employ the light curve without the data at first fading for to fit the second fading event.
Accordingly, we obtain the two transiting parameter sets which are Tc, b, Rp/Rsand baseline correction factors for one double fading light curve. This assumption corresponds to two objects independently orbiting the host star.
The variations of Rp/Rs and b are shown in Figures 3.11 and 3.12, re-spectively. These time variations include the degeneracy between Rp/Rs and b due to the obtained grazing orbit. Hence, these parameters have po-tentially more uncertainty than the best-fit parameters. However, either or both of Rp/Rs and b certainly exhibit large fluctuations. We will discuss these results for the long-term observations in the next chapter, combined with the results of Chapter 2.
Table 3.2: Best-fit parameters and uncertainties Common parameter Value Uncertainty
a/Rs 2.189 +0.025−0.025
Independent parameter
2012 Nov. 27 Value Uncertainty
Tc [BJDTDB−2450000] 6259.14947 +0.00056−0.00050
b 0.722 +0.017−0.017
Rp/Rs 0.115 +0.002−0.002
duration [days] 0.0518 +0.0009−0.0008
k0 0.9127 +0.0023−0.0030
kt 0.2220 +0.0056−0.0056
kt2 -3.71 +0.06−0.07
kz 0.0797 +0.0025−0.0019
kx 0.0 (fixed)
ky 0.0 (fixed)
2012 Dec. 1 Value Uncertainty
Tc [BJDTDB−2450000] 6263.17009 +0.00085−0.00084
b 0.888 +0.027−0.012
Rp/Rs 0.096 +0.006−0.004
duration [days] 0.0426 +0.0008−0.0007
k0 1.1086 +0.0033−0.0036
kt 0.1369 +0.0044−0.0047
kt2 0.0 (fixed)
kz -0.0848 +0.0027−0.0027
kx -0.00048 +0.00008−0.00012
ky 0.0 (fixed)
2013 Dec. 2 Value Uncertainty
Tc [BJDTDB−2450000] 6629.07668 +0.00060−0.00051
b 1.056 +0.019−0.016
Rp/Rs 0.246 +0.015−0.013
duration [days] 0.0487 +0.0009−0.0008
k0 0.8959 +0.0016−0.0021
kt 0.5100 +0.0091−0.0136
kt2 -4.36 +0.11−0.09
kz 0.0701 +0.0012−0.0010
kx -0.00847 +0.00066−0.00073
ky 0.0 (fixed)
Table 3.3: Continuation of table 3.2.
Independent parameter
2014 Jan. 24 Value Uncertainty
Tc [BJDTDB−2450000] 6681.97456 +0.00035−0.00037
b 0.704 +0.014−0.016
Rp/Rs 0.132 +0.002−0.002
duration [days] 0.0568 +0.0010−0.0009
k0 1.0048 +0.0004−0.0004
kt 0.1015 +0.0049−0.0047
kt2 -1.49 +0.13−0.13
kz 0.0 (fixed)
kx 0.0 (fixed)
ky 0.0 (fixed)
2014 Feb. 10 Value Uncertainty
Tc [BJDTDB−2450000] 6699.01860 +0.00051−0.00055
b 0.846 +0.017−0.023
Rp/Rs 0.138 +0.006−0.005
duration [days] 0.0538 +0.0009−0.0008
k0 1.0083 +0.0004−0.0004
kt 0.0111 +0.0075−0.0085
kt2 -2.10 +0.15−0.08
kz 0.0 (fixed)
kx 0.0 (fixed)
ky 0.0 (fixed)
2014 Feb. 19 Value Uncertainty
Tc [BJDTDB−2450000] 6707.98112 +0.00151−0.00142
b 0.687 +0.047−0.061
Rp/Rs 0.130 +0.004−0.003
duration [days] 0.0579 +0.0010−0.0009
k0 0.9244 +0.0012−0.0023
kt 0.0588 +0.0076−0.0111
kt2 -5.77 +0.14−0.10
kz 0.0727 +0.0015−0.0008
kx 0.0 (fixed)
ky 0.0 (fixed)
2014 Nov. 18 Value Uncertainty
Tc [BJDTDB−2450000] 6980.10328 +0.00090−0.00152
b 0.632 +0.035−0.080
Rp/Rs 0.144 +0.003−0.003
duration [days] 0.0660 +0.0011−0.0010
k0 1.0038 +0.0005−0.0005
kt -0.2926 +0.0084−0.0103
kt2 2.10 +0.17−0.13
kz 0.0 (fixed)
kx 0.0 (fixed)
ky -0.00037 +0.00030−0.00031
Table 3.4: Continuation of table 3.3.
Independent parameter First fading Second fading
2014 Nov. 22 Value Uncertainty Value Uncertainty
Tc [BJDTDB−2450000] 6984.15002 +0.00031−0.00034 6984.19868 +0.00050−0.00047
b 1.061 +0.045−0.035 0.888 +0.015−0.013
Rp/Rs 0.232 +0.037−0.027 0.109 +0.005−0.003
duration [days] 0.0447 +0.0008−0.0007 0.0436 +0.0008−0.0007
k0 1.0453 +0.0065−0.0029 1.0074 +0.0002−0.0002 kt -0.0905 +0.0016−0.0016 -0.0605 +0.0023−0.0027
kt2 1.75 +0.17−0.09 0.0 (fixed)
kz -0.0375 +0.0026−0.0056 0.0 (fixed)
kx 0.0 (fixed) 0.0 (fixed)
ky 0.0 (fixed) -0.00289 +0.00040−0.00030
2014 Dec. 5 Value Uncertainty
Tc [BJDTDB−2450000] 6997.15430 +0.00054−0.00056
b 1.041 +0.072−0.057
Rp/Rs 0.211 +0.057−0.042
duration [days] 0.0449 +0.0008−0.0007
k0 0.9940 +0.0002−0.0002
kt 0.0105 +0.0030−0.0030
kt2 0.81 +0.03−0.03
kz 0.0 (fixed)
kx 0.0 (fixed)
ky 0.0 (fixed)
2015 Jan. 10 Value Uncertainty Value Uncertainty
Tc [BJDTDB−2450000] 7033.02545 +0.00048−0.00047 7033.06933 +0.00153−0.00123
b 0.842 +0.010−0.010 1.026 +0.076−0.034
Rp/Rs 0.105 +0.003−0.003 0.122 +0.064−0.028 duration [days] 0.0477 +0.0008−0.0007 0.0348 +0.0007−0.0006 k0 1.0085 +0.0012−0.0009 1.0100 +0.0007−0.0011 kt -0.1442 +0.0037−0.0034 -0.1384 +0.0039−0.0036
kt2 0.0 (fixed) 0.0 (fixed)
kz -0.0090 +0.0008−0.0009 -0.0094 +0.0009−0.0006
kx 0.0 (fixed) 0.0 (fixed)
ky 0.0 (fixed) 0.0 (fixed)
2015 Dec. 1 Value Uncertainty
Tc [BJDTDB−2450000] 6980.13220 +0.00051−0.00050 6980.17678 +0.00038−0.00038
b 0.974 +0.017−0.020 1.165 +0.047−0.069
Rp/Rs 0.142 +0.011−0.013 0.327 +0.041−0.060 duration [days] 0.0442 +0.0008−0.0007 0.0493 +0.0009−0.0008 k0 1.0460 +0.0025−0.0013 1.0272 +0.0036−0.0040
kt -0.0826 +0.0026−0.0031 -0.0594 +0.0057−0.0043
kt2 1.72 +0.08−0.05 1.13 +0.10−0.14
kz -0.0406 +0.0011−0.0022 -0.0241 +0.0036−0.0031
kx 0.0 (fixed) 0.0 (fixed)
ky 0.0 (fixed) 0.0 (fixed)
Table 3.5: Continuation of table 3.4.
Independent parameter
2016 Feb. 9 (g2′) Value Uncertainty Tc [BJDTDB−2450000] 7428.07422 +0.00094−0.00095
b 1.125 +0.101−0.204
Rp/Rs 0.406 +0.088−0.160
duration [days] 0.0617 +0.0011−0.0010
k0 1.0060 +0.0027−0.0030
kt -0.0250 +0.0265−0.0302
kt2 0.0 (fixed)
kz 0.0 (fixed)
kx 0.0 (fixed)
ky 0.0 (fixed)
2016 Feb. 9 (r′2) Value Uncertainty Tc [BJDTDB−2450000] 7428.07422 +0.00094−0.00095
b 1.125 +0.101−0.204
Rp/Rs 0.333 +0.092−0.150
duration [days] 0.0539 +0.0010−0.0009
k0 0.9998 +0.0011−0.0011
kt -0.0007 +0.0118−0.0110
kt2 0.0 (fixed)
kz 0.0 (fixed)
kx 0.0 (fixed)
ky 0.0 (fixed)
2016 Feb. 9 (zs,2) Value Uncertainty Tc [BJDTDB−2450000] 7428.07422 +0.00094−0.00095
b 1.125 +0.101−0.204
Rp/Rs 0.271 +0.092−0.148
duration [days] 0.0450 +0.0008−0.0007
k0 0.9955 +0.0008−0.0006
kt -0.0567 +0.0074−0.0062
kt2 0.0 (fixed)
kz 0.0 (fixed)
kx 0.0 (fixed)
ky 0.0 (fixed)
0.96 0.97 0.98 0.99 1 1.01 1.02 1.03
Relative flux
J-band
0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.1 0.15 0.2 0.25 0.3
Residual
BJD - 2456259
0.98 0.99 1 1.01 1.02
Relative flux
J-band
0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.15 0.2 0.25
Residual
BJD - 2456263
Figure 3.1: Raw light curves of CVSO 30 (upper panels), the light curves corrected by the baseline correction (middle panels), and the residuals be-tween the observed data and the best-fit model (lower panels). The gray dots represent relative flux data. The black open circles represent 0.01 days binned data. The solid lines represent the best-fit transit models. The top panels show the data observed on 2012 November 27 and the bottom panels show the data observed on 2012 December 1.
0.97 0.98 0.99 1 1.01 1.02 1.03
Relative flux
J-band
0.97 0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.05 0.1 0.15
Residual
BJD - 2456629
0.98 0.99 1 1.01 1.02 1.03
Relative flux
J-band
0.97 0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.95 1 1.05
Residual
BJD - 2456681
Figure 3.2: Same as Figure 3.1, but observed on 2013 December 2 (top panels) and 2014 January 24 (bottom panels).
0.98 0.99 1 1.01 1.02 1.03
Relative flux
J-band
0.97 0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.95 1 1.05 1.1
Residual
BJD - 2456698
0.97 0.98 0.99 1 1.01 1.02 1.03
Relative flux
J-band
0.97 0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.95 1 1.05
Residual
BJD - 2456707
Figure 3.3: Same as Figure 3.2, but observed on 2014 February 10 (top panels), 2014 February 19 (upper right).
0.98 0.99 1 1.01 1.02 1.03
Relative flux
J-band
0.97 0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.1 0.15 0.2
Residual
BJD - 2456980
Figure 3.4: Same as Figure 3.3, but observed on 2014 November 18.
0.98 0.99 1 1.01 1.02 1.03 1.04
Relative flux
J-band
0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.1 0.15 0.2 0.25 0.3
Residual
BJD - 2456984
0.98 0.99 1 1.01 1.02 1.03 1.04
Relative flux
J-band
0.97 0.98 0.99 1 1.01 1.02
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.1 0.15 0.2 0.25 0.3
Residual
BJD - 2456984
Figure 3.5: Same as Figure 3.4, but observed on 2014 November 22. Top panels are corrected by the first fading event and bottom panels are corrected by the second fading event.
0.97 0.98 0.99 1 1.01 1.02 1.03
Relative flux
J-band
0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.05 0.1 0.15 0.2 0.25
Residual
BJD - 2456997
Figure 3.6: Same as Figure 3.5, but observed on 2014 December 5.
0.98 0.99 1 1.01 1.02 1.03
Relative flux
J-band
0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.9 0.95 1 1.05 1.1
Residual
BJD - 2457032
0.98 0.99 1 1.01 1.02 1.03
Relative flux
J-band
0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.9 0.95 1 1.05 1.1
Residual
BJD - 2457032
Figure 3.7: Same as Figure 3.6, but observed on 2015 January 10. Top panels are corrected by the first fading event and bottom panels are corrected by the second fading event.
0.97 0.98 0.99 1 1.01 1.02
Relative flux
J-band
0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.05 0.1 0.15 0.2 0.25 0.3
Residual
BJD - 2457358
0.97 0.98 0.99 1 1.01 1.02
Relative flux
J-band
0.97 0.98 0.99 1 1.01
Relative flux
J-band
-0.02 -0.01 0 0.01 0.02
0.05 0.1 0.15 0.2 0.25 0.3
Residual
BJD - 2457358
Figure 3.8: Same as Figure 3.7, but observed on 2015 December 1. Top panels are corrected by the first fading event and bottom panels are corrected by the second fading event.
0.94 0.96 0.98 1 1.02 1.04 1.06
Relative flux
g‘2-band
0.94 0.96 0.98 1 1.02 1.04
Relative flux
g‘2-band
-0.04 -0.02 0 0.02 0.04
0.95 1 1.05 1.1
Residual
BJD - 2457427
0.97 0.98 0.99 1 1.01 1.02 1.03
Relative flux
r‘2-band
0.97 0.98 0.99 1 1.01 1.02
Relative flux
r‘2-band
-0.02 -0.01 0 0.01 0.02
0.95 1 1.05 1.1
Residual
BJD - 2457427
Figure 3.9: Same as Figure 3.8, but observed on 2016 February 9. Top panels are observed in the g2′-band and bottom panels are observed in the r′2-band.
0.98 0.99 1 1.01 1.02
Relative flux
zs,2-band
0.98 0.99 1 1.01
Relative flux
r‘2-band
-0.02 -0.01 0 0.01 0.02
0.95 1 1.05 1.1
Residual
BJD - 2457427
Figure 3.10: Same as Figure 3.9, but observed on 2016 February 9 in the zs,2-band.
0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
6200 6400 6600 6800 7000 7200 7400 7600
Rp/Rs
Time [BJD - 2450000]
Single fading (J-band) First fading (J-band) Second fading (J-band) g-band r-band zs-band
Figure 3.11: Time evolution of fittedRp/Rs. The black points showRp/Rs
of single fading events observed in the J-band. The magenta points show Rp/Rs of the first of the double fading events observed in theJ-band. The black points showRp/Rs of the second of the double fading events observed in theJ-band. The blue, green and red points showRp/Rs of single fading events observed in theg′2,r2′ and zs,2-band, respectively.
0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3
6200 6400 6600 6800 7000 7200 7400 7600
Impact parameter
Time [BJD - 2450000]
Single fading First fading Second fading
Figure 3.12: Time evolution of fitted b. The red points show b of single fading events. The green points show b of the first of the double fading events. The blue points show bof the second of the double fading events.
Discussion
We found the wavelength dependence of fading depth in Chapter 2. Fur-ther, we found the double fading events and the variations of best-fit transit parameters in Chapter 3. In this chapter, we discuss these results and the origin of the fading events of CVSO 30.