- Email: [email protected]
VRI photometry and light curve analysis of short period W UMa-Type 1SWASP J222514.69 + 361643.0
New Astronomy 56 (2017) 50–53
Contents lists available at ScienceDirect
New Astronomy journal homepage: www.elsevier.com/locate/newast
VRI photometry and light curve analysis of short period W UMa-Type 1SWASP J222514.69 + 361643.0 M.H. El-Depsey a,c,∗, M.S. Abo-Alazm a,c, M.S. Saad a,c, I.A. Hassan b, A.M.K. Shaltout b, I. Zeid a,c, A. Shokry a,c, M. Darwish a,c a b c
Astronomy Dept., National Research Institute of Astronomy and Geophysics, (NRIAG), Helwan, Cairo, Egypt Astronomy Dept. and Meteorology, Faculty of Science, Al-Azhar University, Cairo, Egypt Kottamia Center of Scientific Excellence in Astronomy and Space Sciences (KCScE), STDF, ASRT, Cairo, Egypt
h i g h l i g h t s • • • • •
Photometric observations of an eclipsing binary system have been obtained. The system was found to be as A-subtype of W UMa with fill-out factor of about 53%. We estimated the orbital and absolute parameters of the system. The evolution status was performed along with ZAMS and TAMS tracks. The spectral type of the system components are K2 and K3.
a r t i c l e
i n f o
Article history: Received 8 March 2017 Revised 15 April 2017 Accepted 17 April 2017 Available online 19 April 2017
a b s t r a c t We present the first light curve analysis and modeling for the short period close binary 1SWASP J222514.69 + 361643.0. The results show that the system is in over contact with factor ƒ = 53%. The primary component is the massive and hotter one. The system is A-subtype W UMa eclipsing binary with spectral types K2 and K3, respectively. © 2017 Elsevier B.V. All rights reserved.
Keywords: Variable stars W Uma eclipsing binary Evolution traces
1. Introduction W UMa-type variable stars are interacting binaries where both components are over filling their critical Roche lobe and share a common convective envelope. 1SWASP 222,514.69 + 361643.0 is such a system; here we simplify its name to 1SWASP J2225 (Lohr et al., 2012). 1SWASP J2225 is one of 53 short period eclipsing binary stars that were identified by Super WASP (Norton et al., 2011). This project surveys bright stars over almost the whole sky since 2004, looking for photometric variations indicative of exoplanetary transits. It has discovered several tens of thousands of new variable stars, the majority of which appear to be eclipsing binaries, here we are dealing with the star 1SWASP J2225 (α = 22h 25m 14.69s , δ = + 36°16 43.0 ) with a period P = 0.224734 day (Lohr et al., 2012). The system 1SWASP J2225 was classi-
∗
Corresponding author. E-mail address: m_deps20 0 [email protected] (M.H. El-Depsey).
http://dx.doi.org/10.1016/j.newast.2017.04.009 1384-1076/© 2017 Elsevier B.V. All rights reserved.
fied as a short period W UMa star with apparent magnitude Vmax = 12.63 mag. 2. Observations and data reduction Photometric observations of the 1SWASP J2225 were carried out in the night of 2016 October 6 by using a 2kX2k CCD camera attached to the Newtonian focus of the 1.88 m Kottamia reflector telescope in Egypt. The differential photometry was performed with respect to 2MASS 22250,096 + 3614201 and 2MASS 22251069 + 3619494, as comparison (C) and check (CK) stars, respectively. All times were corrected to HJD. The system was observed in the VRI bands. The reduction of observed frames including bias and flat frames was performed using the software package C-Munipack (Motl, 2007). Table 1 lists the variable, comparison and check stars with their coordinates. The epochs of eclipse times in different bands were determined with the Kwee and van Woerden (1956) method. The mean values of new times of primary and secondary minima are listed in Table 2. Using the listed times of minima and period we deter-
M.H. El-Depsey et al. / New Astronomy 56 (2017) 50–53 Table 1 Coordinates of the variable star 1SWASP J2225, comparison star and check star. Object
Star ID
α 2000
δ 2000
Variable Comparison Check
1SWASP J222514.69 + 361643.0 2MASS 22250096 + 3614201 2MASS 22250609 + 3616293
222514.69 336.254009 336.275378
+361643.0 +36.238941 +36.274818
Table 2 The times of minima for 1SWASP J2225. Filter
MinI
MinII
V R I
2457668.2617 ± 0.0090 2457668.2619 ± 0.0050 2457668.2619 ± 0.0050
2457668.371 ± 0.0 0 036 2457668.37148 ± 0.0 0 04 2457668.37209 ± 0.0 0 04
51
Table 3 The orbital solution for spotted and unspotted models for 1SWASP J2225 in different band widths with the spot parameters. Parameter
V (Spot)
R (Spot)
I (Spot)
5500 A˚ 5010 4800 ± 70 0.435 ± 0.0027 2.6 ± 0.0056 0.32 0.5 0.537 53 ± 0.11 0.453747 0.491030 0.531260 0.318745 0.337668 0.399449 0.716 0.0096 S(2) 90° 110° 19 0.2
70 0 0 A˚ 5010 4800 ± 116 0.4 ± 0.0022 2.55 ± 0.0040 0.32 0.5 0.537 54 ± 0.011 0.457405 0.495058 0.532671 0.308983 0.326598 0.384846 0.758 0.028
90 0 0 A˚ 5010 4800 ± 134 0.402 ± 0.0017 2.579 ± 0.0038 0.32 0.5 0.537 54 ± 0.14 0.451942 0.487562 0.522625 0.303813 0.320122 0.371227 0.767 0.0194
T1 (K) T2 (K) q Ω1 = Ω2 g1 = g2 A1 = A2 X1 = X2 i(◦) r pole1 r side1 r back1 r pole2 r side2 r back2 L1 /(l1 +l2 ) (o-c)2 Spot parameter latitude longitude Radius Temp-factor
Fig. 1. The observed phase diagrams of the system in V, R and I filters.
mined the ephemeris Eq. (1).
HJD MinI = 2457668.2618 ± (0.0063 ) + 0.d 224734X E
(1)
Fig. 1 shows the observed phase diagrams of the system in the V, R and I filters. The table of data shows the difference in the magnitude between the variable and comparison and check stars together with the corresponding HJD in V, R and I filters, respectively. This data table is available at the following link: https://www.dropbox.com/ s/vx7kq89amrs5xpi/Data.txt?dl=0 3. Light curve analysis In order to model the light curves of 1SWASP J2225 W UMa, we applied PHOEBE (Prša and Zwitter 2005). PHOEBE (PHysics Of Eclipsing BinariEs) is a modeling software for eclipsing binaries which based on the Wilson–Devinney code. We assumed for the gravity-darkening coefficients g1 = g2 = 0.32 (Lucy, 1967) and the bolometric albedo exponents A1 = A2 = 0.5 (Rucinski, 1969) which are appropriate for the convective envelopes (Teff < 7500 k) of late spectral type stars. Bolometric limb darkening values were adopted using Van Hamme (1993). To determine the mean surface temperature of star1 (T1 ), we used the value of the color index J-H published in 2MASS catalogue = 0.502 mag which corresponds to mean surface temperature of primary star (T1 ) = 5010 K. The adjustable parameters are the orbital inclination (i), the mean temperature of the secondary star (T2 ) and the potential of the components Ω = Ω1 = Ω2 .
Fig. 2. The fitted VRI light curves with synthetic spot model (solid line) for the system 1SWASP J2225.
The characteristic parameters, describing the observed light curves, show a difference between the two maxima of the light curve in the VRI bands. This difference may refer to the presence of an O’ Connell effect (O’Connell, 1951) or presence of spot(s) on the stellar surface. The analysis yields a model with a spot on the secondary star. The best photometric fitting was achieved after several runs by including a cool spot at latitude 90° and longitude 110°on the less massive component. Its radius is about 19° and temperature is a factor 0.2 cooler than its surrounding photosphere. The absolute physical parameters of the system are calculated. The analysis of the light curves shows that the primary component is massive and hotter than the secondary one, where the difference in the temperature between the components is about 210 K. The parameters of the accepted solution are listed in Table 3, while Fig. 2 shows the best fit for the model parameter from PHOEBE and the observed light curve. According to the accepted orbital solution, the components of the system are of spectral type K2 and K3, respectively (Cox, 20 0 0). One can deduce that J2225 system is classified as A-subtype W UMa eclipsing binary (Rucinski, 1973).
52
M.H. El-Depsey et al. / New Astronomy 56 (2017) 50–53 Table 4 The absolute physical parameters for 1SWASP J2225. Element
M(M ) R(R )
Primary 0.8466 Secondary 0.3682
T(T ) L(L ) Mbol
0.9426 0.867 0.8657 0.830
0.502 0.356
Sp.type Logg(cgs) Dist(pc)
5.441 K2 5.812 K3
4.41 4.45
217
mary component is M1 = 0.85 Mʘ , while the mass of the secondary component is directly calculated from the estimated mass ratio of the system (q = m2 /m1 ) as M2 = 0.37 Mʘ . The radii of the two components R1 (Rʘ ), R2 (Rʘ ) and bolometric magnitudes M1bol and M2bol were calculated and are listed together in Table 4. We used the photometric and absolute parameters to calculate the distance (d) of the system, d = 10(m-Mv+5)/5) , where m and Mv are the apparent and absolute magnitude for the system, respectively. The calculations lead to an average distance of the system is 217 ± 24 Pc. 4. Evolution status of 1SWASP J2225
Fig. 3. The configuration of 1SWASP J2225 in phases of 0.00, 0.25, 0.50 and 0.75 with cool spot on the secondary star.
The geometric structure was derived using the software Package Binary Maker 3.0 (Bradstreet and Steelman, 2002) and the calculated parameters are presented in Fig. 3. The absolute physical parameters for the components of the system are calculated using the Teff – mass relation by Harmanec (1988). The mass of the pri-
Using the physical parameters listed in Table 4 we investigated the current evolutionary status of the system. Fig. 4 shows the two components of the system on the mass luminosity (M– L) and mass–radius (M–R) relations along with the evolutionary tracks computed by Mowlavi et al. (2012) for both Zero Age Main Sequence (ZAMS) and Terminal Age Main Sequence (TAMS) with metal abundance of z = 0. 014. The primary component lies between the ZAMS and TAMS tracks, while the secondary component lies slightly above the TAMS track. This indicates that, the primary component is a main sequence star, while the secondary has a structure different from that of a main sequence star. Also the mass effective temperature relation (M–Teff ) for intermediate and low mass stars (Malkov, 2007), Fig. 5 reveals a good fit for the primary component and poor fit for the secondary one of the system. As is it clear from the figures, the primary component follow closely the relations for main sequence stars, while the secondary component is over-luminous with temperature and radius larger than that expected for main-sequence stars. This may be the result of energy transfer from the primary to the secondary star through the common convective envelope (Lucy, 1967). 5. Conclusion We have presented a photometric solution for the eclipsing binary 1SWASP J2225 obtained from the new CCD photometric ob-
Fig. 4. The position of both components of 1SWASP J2225 along with ZAMS and TAMS for the Mass–Radius (left panel) and Mass–Luminosity relations calculated by Mowlavi et al. (2012) (right panel).
M.H. El-Depsey et al. / New Astronomy 56 (2017) 50–53
53
Fig. 5. Position of both components of 1SWASP J2225 on the Mass – Teff relation for low-intermediate mass stars by Malkov (2007).
servations with complete phase coverage in the VRI filters. The new observations indicate that: •
•
•
•
• •
The star is A-type W UMa with a high degree of over-contact ∼53% and mass ratio q = 0.435. The difference in the average temperatures between the two components is ∼210 K. The light curve asymmetric is fitted with a cool spot on the less massive component. The absolute physical parameters of the two components are obtained based on the results of the light curve solution. The spectral types of the system components are K2 and K3. The calculations lead to an average distance of the system∼217 ± 24 Pc.
Spectroscopic observations and long term photometric monitoring of 1SWASP J2225 are highly required to improve its main parameters. Acknowledgments This research granted by Science and Technology Development Fund (STDF) N5217. NASA’s Astrophysics Data System, SIMBAD,
ADS, ESO DSS databases is gratefully acknowledged. This publication makes use of data products from the Two Micron All Sky Survey. We are very grateful to the team of Kotamia Astronomical Observatory, Dr. F. I. Elnagahy, M. Ismail, D. El Sayed and I. Helmy. We would like to give thanks to Dr. N. M. Ahmed and D. Fouda, for their helpful discussions and advice. References Bradstreet, D.H., Steelman, D.P., 2002. BAAS 34, 1224. Cox, A.N., 20 0 0. Book Review: Allen’s Astrophysical Quantities, 4th ed. Springer. Harmanec, P., 1988. Bull. Astron. Inst. Czechosl. 39, 329. Kwee, K., Van Worden, H., 1956. BAN 12, 327. Lohr, M.E., Norton, A.J., Kolb, U.C., Anderson, D.R., Faedi, F., West, R.G., 2012. A&A 542, 124. Lucy, L., 1967. Z.F. Astrophys. 65, 89. Malkov, O.Yn., 2007. MNRAS 382, 1073. Motl D., 2007. C-Munipack Project v1.2.32, availablefrom: http://sourceforge.net/ projects/c-munipack/files Mowlavi, N., Eggenberger, P., Meynet, G., Ekström, S., Georgy, C., Maeder, A., Chrnel, C., Eyer, L., 2012. A&A 541, 41. Norton, A.J., Payne, S.G., Evans, T., et al., 2011. A&A 528, 90. O’Connell, D.J.K., 1951. Pub. River View College Obs. 2, 85. Prša, A., Zwitter, T., 2005. ApJ 628, 426. Rucinski, S., 1969. Acta Astron. 19, 156R. Rucinski, S.M., 1973. AcA. 23, 79R. Van Hamme, W., 1993. AJ 106, 2096.
Contents lists available at ScienceDirect
New Astronomy journal homepage: www.elsevier.com/locate/newast
VRI photometry and light curve analysis of short period W UMa-Type 1SWASP J222514.69 + 361643.0 M.H. El-Depsey a,c,∗, M.S. Abo-Alazm a,c, M.S. Saad a,c, I.A. Hassan b, A.M.K. Shaltout b, I. Zeid a,c, A. Shokry a,c, M. Darwish a,c a b c
Astronomy Dept., National Research Institute of Astronomy and Geophysics, (NRIAG), Helwan, Cairo, Egypt Astronomy Dept. and Meteorology, Faculty of Science, Al-Azhar University, Cairo, Egypt Kottamia Center of Scientific Excellence in Astronomy and Space Sciences (KCScE), STDF, ASRT, Cairo, Egypt
h i g h l i g h t s • • • • •
Photometric observations of an eclipsing binary system have been obtained. The system was found to be as A-subtype of W UMa with fill-out factor of about 53%. We estimated the orbital and absolute parameters of the system. The evolution status was performed along with ZAMS and TAMS tracks. The spectral type of the system components are K2 and K3.
a r t i c l e
i n f o
Article history: Received 8 March 2017 Revised 15 April 2017 Accepted 17 April 2017 Available online 19 April 2017
a b s t r a c t We present the first light curve analysis and modeling for the short period close binary 1SWASP J222514.69 + 361643.0. The results show that the system is in over contact with factor ƒ = 53%. The primary component is the massive and hotter one. The system is A-subtype W UMa eclipsing binary with spectral types K2 and K3, respectively. © 2017 Elsevier B.V. All rights reserved.
Keywords: Variable stars W Uma eclipsing binary Evolution traces
1. Introduction W UMa-type variable stars are interacting binaries where both components are over filling their critical Roche lobe and share a common convective envelope. 1SWASP 222,514.69 + 361643.0 is such a system; here we simplify its name to 1SWASP J2225 (Lohr et al., 2012). 1SWASP J2225 is one of 53 short period eclipsing binary stars that were identified by Super WASP (Norton et al., 2011). This project surveys bright stars over almost the whole sky since 2004, looking for photometric variations indicative of exoplanetary transits. It has discovered several tens of thousands of new variable stars, the majority of which appear to be eclipsing binaries, here we are dealing with the star 1SWASP J2225 (α = 22h 25m 14.69s , δ = + 36°16 43.0 ) with a period P = 0.224734 day (Lohr et al., 2012). The system 1SWASP J2225 was classi-
∗
Corresponding author. E-mail address: m_deps20 0 [email protected] (M.H. El-Depsey).
http://dx.doi.org/10.1016/j.newast.2017.04.009 1384-1076/© 2017 Elsevier B.V. All rights reserved.
fied as a short period W UMa star with apparent magnitude Vmax = 12.63 mag. 2. Observations and data reduction Photometric observations of the 1SWASP J2225 were carried out in the night of 2016 October 6 by using a 2kX2k CCD camera attached to the Newtonian focus of the 1.88 m Kottamia reflector telescope in Egypt. The differential photometry was performed with respect to 2MASS 22250,096 + 3614201 and 2MASS 22251069 + 3619494, as comparison (C) and check (CK) stars, respectively. All times were corrected to HJD. The system was observed in the VRI bands. The reduction of observed frames including bias and flat frames was performed using the software package C-Munipack (Motl, 2007). Table 1 lists the variable, comparison and check stars with their coordinates. The epochs of eclipse times in different bands were determined with the Kwee and van Woerden (1956) method. The mean values of new times of primary and secondary minima are listed in Table 2. Using the listed times of minima and period we deter-
M.H. El-Depsey et al. / New Astronomy 56 (2017) 50–53 Table 1 Coordinates of the variable star 1SWASP J2225, comparison star and check star. Object
Star ID
α 2000
δ 2000
Variable Comparison Check
1SWASP J222514.69 + 361643.0 2MASS 22250096 + 3614201 2MASS 22250609 + 3616293
222514.69 336.254009 336.275378
+361643.0 +36.238941 +36.274818
Table 2 The times of minima for 1SWASP J2225. Filter
MinI
MinII
V R I
2457668.2617 ± 0.0090 2457668.2619 ± 0.0050 2457668.2619 ± 0.0050
2457668.371 ± 0.0 0 036 2457668.37148 ± 0.0 0 04 2457668.37209 ± 0.0 0 04
51
Table 3 The orbital solution for spotted and unspotted models for 1SWASP J2225 in different band widths with the spot parameters. Parameter
V (Spot)
R (Spot)
I (Spot)
5500 A˚ 5010 4800 ± 70 0.435 ± 0.0027 2.6 ± 0.0056 0.32 0.5 0.537 53 ± 0.11 0.453747 0.491030 0.531260 0.318745 0.337668 0.399449 0.716 0.0096 S(2) 90° 110° 19 0.2
70 0 0 A˚ 5010 4800 ± 116 0.4 ± 0.0022 2.55 ± 0.0040 0.32 0.5 0.537 54 ± 0.011 0.457405 0.495058 0.532671 0.308983 0.326598 0.384846 0.758 0.028
90 0 0 A˚ 5010 4800 ± 134 0.402 ± 0.0017 2.579 ± 0.0038 0.32 0.5 0.537 54 ± 0.14 0.451942 0.487562 0.522625 0.303813 0.320122 0.371227 0.767 0.0194
T1 (K) T2 (K) q Ω1 = Ω2 g1 = g2 A1 = A2 X1 = X2 i(◦) r pole1 r side1 r back1 r pole2 r side2 r back2 L1 /(l1 +l2 ) (o-c)2 Spot parameter latitude longitude Radius Temp-factor
Fig. 1. The observed phase diagrams of the system in V, R and I filters.
mined the ephemeris Eq. (1).
HJD MinI = 2457668.2618 ± (0.0063 ) + 0.d 224734X E
(1)
Fig. 1 shows the observed phase diagrams of the system in the V, R and I filters. The table of data shows the difference in the magnitude between the variable and comparison and check stars together with the corresponding HJD in V, R and I filters, respectively. This data table is available at the following link: https://www.dropbox.com/ s/vx7kq89amrs5xpi/Data.txt?dl=0 3. Light curve analysis In order to model the light curves of 1SWASP J2225 W UMa, we applied PHOEBE (Prša and Zwitter 2005). PHOEBE (PHysics Of Eclipsing BinariEs) is a modeling software for eclipsing binaries which based on the Wilson–Devinney code. We assumed for the gravity-darkening coefficients g1 = g2 = 0.32 (Lucy, 1967) and the bolometric albedo exponents A1 = A2 = 0.5 (Rucinski, 1969) which are appropriate for the convective envelopes (Teff < 7500 k) of late spectral type stars. Bolometric limb darkening values were adopted using Van Hamme (1993). To determine the mean surface temperature of star1 (T1 ), we used the value of the color index J-H published in 2MASS catalogue = 0.502 mag which corresponds to mean surface temperature of primary star (T1 ) = 5010 K. The adjustable parameters are the orbital inclination (i), the mean temperature of the secondary star (T2 ) and the potential of the components Ω = Ω1 = Ω2 .
Fig. 2. The fitted VRI light curves with synthetic spot model (solid line) for the system 1SWASP J2225.
The characteristic parameters, describing the observed light curves, show a difference between the two maxima of the light curve in the VRI bands. This difference may refer to the presence of an O’ Connell effect (O’Connell, 1951) or presence of spot(s) on the stellar surface. The analysis yields a model with a spot on the secondary star. The best photometric fitting was achieved after several runs by including a cool spot at latitude 90° and longitude 110°on the less massive component. Its radius is about 19° and temperature is a factor 0.2 cooler than its surrounding photosphere. The absolute physical parameters of the system are calculated. The analysis of the light curves shows that the primary component is massive and hotter than the secondary one, where the difference in the temperature between the components is about 210 K. The parameters of the accepted solution are listed in Table 3, while Fig. 2 shows the best fit for the model parameter from PHOEBE and the observed light curve. According to the accepted orbital solution, the components of the system are of spectral type K2 and K3, respectively (Cox, 20 0 0). One can deduce that J2225 system is classified as A-subtype W UMa eclipsing binary (Rucinski, 1973).
52
M.H. El-Depsey et al. / New Astronomy 56 (2017) 50–53 Table 4 The absolute physical parameters for 1SWASP J2225. Element
M(M ) R(R )
Primary 0.8466 Secondary 0.3682
T(T ) L(L ) Mbol
0.9426 0.867 0.8657 0.830
0.502 0.356
Sp.type Logg(cgs) Dist(pc)
5.441 K2 5.812 K3
4.41 4.45
217
mary component is M1 = 0.85 Mʘ , while the mass of the secondary component is directly calculated from the estimated mass ratio of the system (q = m2 /m1 ) as M2 = 0.37 Mʘ . The radii of the two components R1 (Rʘ ), R2 (Rʘ ) and bolometric magnitudes M1bol and M2bol were calculated and are listed together in Table 4. We used the photometric and absolute parameters to calculate the distance (d) of the system, d = 10(m-Mv+5)/5) , where m and Mv are the apparent and absolute magnitude for the system, respectively. The calculations lead to an average distance of the system is 217 ± 24 Pc. 4. Evolution status of 1SWASP J2225
Fig. 3. The configuration of 1SWASP J2225 in phases of 0.00, 0.25, 0.50 and 0.75 with cool spot on the secondary star.
The geometric structure was derived using the software Package Binary Maker 3.0 (Bradstreet and Steelman, 2002) and the calculated parameters are presented in Fig. 3. The absolute physical parameters for the components of the system are calculated using the Teff – mass relation by Harmanec (1988). The mass of the pri-
Using the physical parameters listed in Table 4 we investigated the current evolutionary status of the system. Fig. 4 shows the two components of the system on the mass luminosity (M– L) and mass–radius (M–R) relations along with the evolutionary tracks computed by Mowlavi et al. (2012) for both Zero Age Main Sequence (ZAMS) and Terminal Age Main Sequence (TAMS) with metal abundance of z = 0. 014. The primary component lies between the ZAMS and TAMS tracks, while the secondary component lies slightly above the TAMS track. This indicates that, the primary component is a main sequence star, while the secondary has a structure different from that of a main sequence star. Also the mass effective temperature relation (M–Teff ) for intermediate and low mass stars (Malkov, 2007), Fig. 5 reveals a good fit for the primary component and poor fit for the secondary one of the system. As is it clear from the figures, the primary component follow closely the relations for main sequence stars, while the secondary component is over-luminous with temperature and radius larger than that expected for main-sequence stars. This may be the result of energy transfer from the primary to the secondary star through the common convective envelope (Lucy, 1967). 5. Conclusion We have presented a photometric solution for the eclipsing binary 1SWASP J2225 obtained from the new CCD photometric ob-
Fig. 4. The position of both components of 1SWASP J2225 along with ZAMS and TAMS for the Mass–Radius (left panel) and Mass–Luminosity relations calculated by Mowlavi et al. (2012) (right panel).
M.H. El-Depsey et al. / New Astronomy 56 (2017) 50–53
53
Fig. 5. Position of both components of 1SWASP J2225 on the Mass – Teff relation for low-intermediate mass stars by Malkov (2007).
servations with complete phase coverage in the VRI filters. The new observations indicate that: •
•
•
•
• •
The star is A-type W UMa with a high degree of over-contact ∼53% and mass ratio q = 0.435. The difference in the average temperatures between the two components is ∼210 K. The light curve asymmetric is fitted with a cool spot on the less massive component. The absolute physical parameters of the two components are obtained based on the results of the light curve solution. The spectral types of the system components are K2 and K3. The calculations lead to an average distance of the system∼217 ± 24 Pc.
Spectroscopic observations and long term photometric monitoring of 1SWASP J2225 are highly required to improve its main parameters. Acknowledgments This research granted by Science and Technology Development Fund (STDF) N5217. NASA’s Astrophysics Data System, SIMBAD,
ADS, ESO DSS databases is gratefully acknowledged. This publication makes use of data products from the Two Micron All Sky Survey. We are very grateful to the team of Kotamia Astronomical Observatory, Dr. F. I. Elnagahy, M. Ismail, D. El Sayed and I. Helmy. We would like to give thanks to Dr. N. M. Ahmed and D. Fouda, for their helpful discussions and advice. References Bradstreet, D.H., Steelman, D.P., 2002. BAAS 34, 1224. Cox, A.N., 20 0 0. Book Review: Allen’s Astrophysical Quantities, 4th ed. Springer. Harmanec, P., 1988. Bull. Astron. Inst. Czechosl. 39, 329. Kwee, K., Van Worden, H., 1956. BAN 12, 327. Lohr, M.E., Norton, A.J., Kolb, U.C., Anderson, D.R., Faedi, F., West, R.G., 2012. A&A 542, 124. Lucy, L., 1967. Z.F. Astrophys. 65, 89. Malkov, O.Yn., 2007. MNRAS 382, 1073. Motl D., 2007. C-Munipack Project v1.2.32, availablefrom: http://sourceforge.net/ projects/c-munipack/files Mowlavi, N., Eggenberger, P., Meynet, G., Ekström, S., Georgy, C., Maeder, A., Chrnel, C., Eyer, L., 2012. A&A 541, 41. Norton, A.J., Payne, S.G., Evans, T., et al., 2011. A&A 528, 90. O’Connell, D.J.K., 1951. Pub. River View College Obs. 2, 85. Prša, A., Zwitter, T., 2005. ApJ 628, 426. Rucinski, S., 1969. Acta Astron. 19, 156R. Rucinski, S.M., 1973. AcA. 23, 79R. Van Hamme, W., 1993. AJ 106, 2096.