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Photoelectric photometry of eclipsing binary V375 cassiopeiae
Pergamon Journals. Printed in Great Britain. 0275-1062/86$10.00+.00
Chin.Astron.Astrophys.10 (1986) 265-271 Act.Astrophys.Sin.
$_ Cl%61
PHOTOELECTRIC
ZHANG
185-192
PHOTOMETRY
Rong-Xian,
Beijing
Observatory,
OF ECLIPSING
ZHANG Ji-tong, Academia
BINARY
LI Qi-sheng,
V375
CASSIOPEIAE
ZHAI Di-shenp
Sinica
Keywords: Stars - Binaries - Close Binaries
Received 1985 May 10
ABSTRACT Some 604 photoelectric BV observations of the eclipsing binary V375 Cas were obtained at Beijing Observatory from August to November 1982. Photometric solution was carried out using the Wilson-Devinney program for the BV light curves. The system is found to be a semidetached binary in which the less massive component fills its Roche lobe and the more massive component nearly does so. It is very similar to RZ Dra. This very interesting system is important for the understanding of the evolution of close binaries. Observatory, and a single channel photometer to carry out photoelectric observations on V375 Cas is a short-period eclipsing binary, V375 Cas. Over eight effective observing and was first discovered by Weber [l]. Between nights, we obtained 604 data points in each 1957 and 1960, the Soviet researchers of the two colours B and V, covering the Solovb'ev [2], Grigolevskii [3], Chupina [4], principal minimum three times, and the Kukarkin and Novikow [S] and Satanova [6] secondary minimum four times. The times of carried out photographic observations of this minima were calculated using the K-W method. star and ascertained it to be a B Lyrae star TABLE 1 lists the BD numbers, V magnitudes Brodskaya [7] and gave its epoch formula. and B-V color indices of the variable, determined its spectral type to be 83. In comparison and check stars. The main extinction coefficients used were those of view of the fact that it is a short-period it is likely to be a the night concerned, the secondary eclipsing binary, coefficients,the monthly averages and the contact binary, hence may be of significance standard stars used in the reduction were in our understanding of the evolution of secondary standards. The differential Accordingly, we early-type close binaries. between the comparison and check stars had carried out a detailed program of photoelectric observations on this object. an observing error 0~0.02. 1.
INTRODUCTION
2.
OBSERVATIONS
'IHELIGHT CURVE AND THE PERIOD
From August to November 1982, we used the 60-cm reflector of Xinglong Station, Beijing TABLE 1
V375 Cas is binary. Its
an early-type light curve
is
B Lyrae eclipsing shown in Fig. 1.
V and B-V r!easurements of the Variable, Comparison and Check Stars V
B-V
HD No. magnitude
111. C.
9.94. 10.03 10.20
0.01 0.01 0.01
+62O2332(V) +62”2333 (c)
+62O2331(Ch) *at light maximum
In.C. 0.25. 0.54 1.12
0.01 0.01 0.01
ZHANG, ZHANG et
266
The normal points data are given in TABLE 2. From the figure, we see that the star shows continuous variation outside the eclipses, that the light curve is basically symmetrical, the principal and secondary maxima are nearly minimum is somewhat deep equai, the-secondary and, at the principal minimum, the color index increases slightly, which shows that Component 2 has a lower temperature than The main features of the light Component 1. curve are listed in TABLE 3. TABLE 4 gives the times of the principal and secondary Combining these values of ours with minima. those we collected from the literature, a weighted least-squares reduction gave the new epoch formula as follows:
TABLE 3s Ph.
Normal
tnt.
Points
of
the N
Light
al.
JD He1 . Mini -
2445635”1514 + 1?47338191 X E CI.00000028 f.0016
In this calculation, minimum times obtained photoelectrically were given weight 10, for those obtained photographically, the weights given by Kukarkin [S] were used. The values O-C based on the new epoch formula are given in TABLE 5, and plotted in Fig. 2. From the latter we see that, over nearly 80 the period of this star shows no years, significant changes.
Curve
of
V375 Cas in
Ph.
ht.
the
Yellow
Band N
__ 0.003Y
0.5825
8
0.5093
0.7084
IS
0.0119
0.5Y22
13
0.5195
0.7299
21
U.OlY4
0.6115
7
0.5316
0.7610
18
0.0261
0.6416
8
0.53921
0.7901
Y
0.0323
0.6792
6
0.5469
0.8155
9
0.0483
0.7447
6
0.5571
0.8461
Y
0.0627
0.8029
6
0.5666
0.8744
9
0.0713
0.8443
6
0.5766
0.9075
9
O.OM17
0.8871
6
0.5874
0.9369
9
0.0937
0.9260
6
0.5974
0.9633
9
0.1052
Il.9514
6
0.6128
1.0020
7
0.1193
O.YY70
6
0.6385
1.0290
8
0.1299
1.0119
6
0.6663
1.0515
9
0.1445
1.0283
14
0.6868
1.0806
10
0.17311
1.0497
7
0.7034
1.0923
11
0.1897
1.0670
7
0.7314
1.1028
9
0.2117
1.0748
17
0.7554
1.0970
17
0.2400
1.0920
15
0.7858
1.0813
25
0.2613
1.0934
6
0.8315
1.0452
9
0.2721
1.0974
6
0.8504
1.0303
9
0.2843
1.0982
8
0.8669
0.9983 0.9792
9
0.3067
1.0799
7
0.8894
0.3456
1.0547
11
0.9057
9
0.3855
0.91152
5
0.9261
0.9237 0.8557
0.4223
0.9053
5
0.9371
0.8018
6
0.4327
0.8863
6
0.9463
0.7621
6
0.4435
o.n417
0.7173
6
0.8020
6 Y
0.9567
0.4565
0.9673
0.6669
6
0.4653
21
0.6131
6
27
0.9778 0.9928
0.5856
16
27
0.
i;‘Ji
0.7666 _ U./2M9
IJ.
4Y57
0.7046
6 6
V37.5
TABLZ
3b
267
Cas
Normal Points of the Lieht Curve of
Ph.
int.
0.0062
V375
Cas
in
the 31ue Band
N
Ph.
Int.
0.7236
15
0.5035
0.9228
9 15
N
0.0153
0.7460
9
0.5127
0.9298
O.OZll
0.7791
6
0.5193
0.9475
9
0.0266
0.8072
6
0.5254
0.9655
12
0.0336
0.8484
9
0.5342
1.0052
15
0.0534
0.9913
3
0.5429
1.0430
12
0.0615
1.0306
6
0.5496
1.0670
3
a.0703
1.0833
6
0.5565
1.1086
9
o.onoo
1.1350
6
0.5675
1.1530
12
0.0951
1.2034
9
0.5778
1.1856
6
0.1144
1.2809
9
0.5901
1.2362
15
0.1311
1.3149
9
0.6028
1.2743
6
0.1449
1.3385
9
0.6234
1.3237
9
0.1608
1.3627
6
0.6547
1‘3710
9
0.1840
1.3844
9
0.6818
1.3s3.l
12
0.2027
1.4032
9
0.7039
1.4050
15
0.2196
1.4201
12
0.7559
1.4259
33
0.2561
1.4209
27
0.7969
1.3907
18
0.3142
1.4079
21
0.8414
1.3574
12
0.3675
1.3591
6
0.8596
1.3276
9
0.40x
1.2561
3
0.8773
1.2922
9
0.4256
1.1679
6
0.8908
1.2489
6
1.2105
6
0.4368
1.1269
6
0.9043
0.4489
1.0694
6
0.9167
1.1493
3
0.4583
I.0291
9
0.9316
1.0710
6
0.4631
A.0132
9
0.9404
1.0140
6
0.4689
0.9911
9
0.9502
0.9568
6
0.4751
0.9634
12
0.9606
0.8825
6
0.4531
0.9370
15
0.9713
0.8157
6
0.4Yi7
0.9229
15
0.9819
0.7597
6
0.4993
0.9220
9
0.9939
0.7236
13
268
ZHANG, ZHANG et al.
0.400.30 050
0.40
0.6C
050
I__
___’
I
110
0.5
0
phase Fig.
1
The
Light
curves
TABLE 3 Min
1.
of
V375
Results
of
Min
Il.
Cas
in
BV Cbservations Mar I.
V
1UT64
IO?42
9m94
li
lOf93
IO?67
IO?19
TABIE JO Hel. 2445000+
of Max II. 9m94 lOTl9
0.25
0.33
n-v
BV bands
4
Times
of
rIinima
filter
of
V375 m. c.
.-
210d0803
B
.0824
V
0.0020
V
0.0005
.I249
n
0.0005
265.3291
V
0.0011
235.1235
.3314 266.0680
0.0006
B
0.0004
V
0.0014
.0683
B
0,0011
294.0618
V
0.0014
.0631
B
0.0016
296.2715
u
0.0009
V
0.0006
V
0.0006
.2743 635.149;
Cas
V375
Cas
principal ccl .depth
secondary rcl.depth
om70
Orn48
omi4
Orn48
269
V37S Cas
TABLE 5 JI)
Ilel.
24ulJooo+ _-.36858.5140 28857.7410 29103.8240 29476.5650 31779.4670 31194.3340 34388.8430 34642.2600 35588.1540 36064.09013 4~600.3070 42621.3780 45210.0814 45235.1242 45265.3303 45266.0682 45294.0625 45296.2729 45635.1497
O-C Values of Past Hinina of V375 Gas (0-C)XlO_' (unit:day)
cycle no. E
weight w
(1) (1) (1)
1.0 10.0 3.0 4.0 5.0 3.0 7.0 5.0 2.0 1.0 1.0 1.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0
-15.3 -10.6 17.6 -7.0 -0.9 -6.9 15.7 11.0 -6.2 27.5 12.0 29.3 0.7 -0.4 -2.3 -1.0 -1.0 -0.7 -1.7
-19351.0 -11357.0 -11220.0 -10967.0 -9404.0 -7765.0 -7633.0 -7461.0 -6819.0 -6496.0 -2738.5 -2045.5 -288.5 -271.5 -251.0 -250.5 -231.5 -230.0 0.0
Ref.
(1) (2) (1) (1) (3) (4) (5) (6) (7) (8) (8) (8) (8) (8) (8) (8)
(1) Kukarkina & Novikov. (2) Erleksova. (3) Grigolevskii. (4) Chupina. (5) Satanova. (6) Wood et al. (7) Diethelm. (8) This Paper.
0:03
t
O.OI
Y
0
+
+
O&2 _________..______
..__
CY
i _-
-20000
+ + + _ . ‘__,_ _____-_..- . .._.......------+
t +
+
I
-15CQO
-IcOoO
r-------
L
,
-so00
0
E
Fig. 2
The O-C plot of the minimum time of Q375 Cas. Crosses are photographic, circles are photoelectric observations.The zero line is the first order fit.
ZHANG, ZHANG et
270
TABLE 6
Photometric
al.
Solution
of
V375 Cas B
V5.500~ 0.6848f0.0012 0.239f0.021 0.258f0.065
0.6959f0.0012 0.467f0.016 0.331f0.056 80'53AO.06 0.608*0.004
i
4 = m,lmt Comp. 1 B
1.000*
A
1.000*
TK La r(pole) r(point) r(side) r(back)
4500A
Comp. 2 0.981rtO.015 0.920f0.036 13865f30 3.0781 =Oina 0.3151~0.0012 0.4243jzO.0012 0.3290~0.0015 0.3614f0.0022
17900*
3.2138*0.0081 0.3779*0.0011 0.4498*0.0036 0.3960f0.0014 0.4183f0.0017
QiIln
3.0781** 2.7229*+
Poet
* adopted value. ** theoretical value.
4.
PHOTOMETRICSOLUTION
The measured points of our B and V light curves were combined into 61 and 62 normal points, respectively, with weights proportional to the number of points involved. We used the program package [10,11] based on the Wilson-Devinney method of synthetic light curve to find a solution. We start by assuming the star to be a detached binary, we then use the “Light Curve Program” of the package to attempt an initial solution close to the observed light curve, and then use the “Differential Correction Program” to obtain the final solution. In what follows Component 1 refers to that component which fs eclipsed during the principal eclipse, and Component 2, during the secondary eclipse. In effecting the photometric solution, we fixed the spectral type of V375 Cas at B3, in accordance with Ref. [7]. According to theoretically calculated tables, the surface temperature for a B3 star is 17900 K. Hence we took as initial temperature ~1=17900 K. Also, as initial values, we took the gravity darkening coefficients 91 =q2 =l, surface thermalalbedoesdl =A2 =l, and for the limb; darkening coefficient in B and V, we took The luminosity of the .B=o.41, ,V=o.34. components were calculated by the Planck the adjustformula. Thus, in our solution, able parameters are: the orbital inclination (i), the pole temperature of Component 2 (T2) the surface potentials of the two components of Component 1 (~1) (Ql,Q) 7 the luminosity in the and the mass ratio q=m2/ml. Since,
course of the solution, the result rapidly converged toward the semi-detached configuration, the latter was then used to continue For a set of different with the iteration. values of 4, the corresponding values of c were calculated and we found that Z was the least around q=O.60; we then adjusted the other parameters 91, 92, Al, AZ, x1, x2 and finally derived that c is a minimum at The variation of c withgis shown q= 0.608. in Fig. 3. X ‘1.5.1.U
0.5-
9
Fig.
3
The z - 9 diagram
of
V37S Cas
The final results of the photometric solution are given in TABLE 6. From these, we see that V375 Cas is a semi-detached system, in which Component 2 (the less massive one) fills
V375 Cas
completely the critical potential surface while Component 1 (the more massive one) nearly does so. See Fig. 4.
271
REFERENCES
Weber, R., L'astronomie 69 (1955) 440. Solob'ev A.V., Astron.Tsir. 176 (1957) Grigolevskii V.M., Perem.Zvezdy 12 [31 (1959) v. 2, 149. ]41 Churpina R., Perem.Zvezdy 12 (1959) v.2 152. Kikarkin B.V., Novikov, I.D., Perem. t51 Zvezdy 13 (1960) v. 5, 366. [61 Satanova E.A., Perem.Zvezdy 13 (1960) v. 2 128. Brodskaya E.S., Isv.Krym.Astr.0b.s. 14 [71 Fig. 4 Configuration of V375 Cas (1955). Wood, F.B. et al, A Finding List for [81 Observers of Interacting Binary Stars, 1980. 5. DISCUSSION Diethelm, R., Bull, D., Bedeckungs Ver. [91 Boeb.d.SchweizerischenAst.Gesselschft. ~375 Cas is an early-type, semi-detached 23 (1976). binary system. The small mass component completely fills its Roche lobe and the large DOI wilson,R.E., Devinney, E.J., Ap.J.166 (1971) 605. mass component nearly does so. In its contact configuration, it is very similar to t111 Leung, K.C., Schneider, D.P., Ap.J.222 (1978) 917. AI Cru [12], BV Eri [13] and RZ Dra [14]. These all have mass ratios around 0.5. We WI Russo,R., Astrophysics & Space Science 77 (1981) 197. are unable to determine its position on the H-R diagram, due to the lack of radial veloc1131 Baade, Duerbeck, H.W., Darimie, M.T., and Yamasaki, A., Astrophysics & Space ity data; but from the present available Science 93 (1983) 69. results, its seems that V375 Cas belongs to Leung, K.C., ZHAI Di-sheng, HUANG Yinthe evolutionary stage of an Algol star after P41 liang, Chin.Astron.Astrophys. 6 (1982) the mass reversal, and, this being so, further 199-204 = Act.Astrophys.Sin.2 (1982) study of this star will be important for 144-151. our understanding of the evolution of earlytype close binaries.
;:;
ACKNOWLEDGEMENT We thank Colleague JIANG Zhao-ji for assistance in realising the computer program.
Chin.Astron.Astrophys.10 (1986) 265-271 Act.Astrophys.Sin.
$_ Cl%61
PHOTOELECTRIC
ZHANG
185-192
PHOTOMETRY
Rong-Xian,
Beijing
Observatory,
OF ECLIPSING
ZHANG Ji-tong, Academia
BINARY
LI Qi-sheng,
V375
CASSIOPEIAE
ZHAI Di-shenp
Sinica
Keywords: Stars - Binaries - Close Binaries
Received 1985 May 10
ABSTRACT Some 604 photoelectric BV observations of the eclipsing binary V375 Cas were obtained at Beijing Observatory from August to November 1982. Photometric solution was carried out using the Wilson-Devinney program for the BV light curves. The system is found to be a semidetached binary in which the less massive component fills its Roche lobe and the more massive component nearly does so. It is very similar to RZ Dra. This very interesting system is important for the understanding of the evolution of close binaries. Observatory, and a single channel photometer to carry out photoelectric observations on V375 Cas is a short-period eclipsing binary, V375 Cas. Over eight effective observing and was first discovered by Weber [l]. Between nights, we obtained 604 data points in each 1957 and 1960, the Soviet researchers of the two colours B and V, covering the Solovb'ev [2], Grigolevskii [3], Chupina [4], principal minimum three times, and the Kukarkin and Novikow [S] and Satanova [6] secondary minimum four times. The times of carried out photographic observations of this minima were calculated using the K-W method. star and ascertained it to be a B Lyrae star TABLE 1 lists the BD numbers, V magnitudes Brodskaya [7] and gave its epoch formula. and B-V color indices of the variable, determined its spectral type to be 83. In comparison and check stars. The main extinction coefficients used were those of view of the fact that it is a short-period it is likely to be a the night concerned, the secondary eclipsing binary, coefficients,the monthly averages and the contact binary, hence may be of significance standard stars used in the reduction were in our understanding of the evolution of secondary standards. The differential Accordingly, we early-type close binaries. between the comparison and check stars had carried out a detailed program of photoelectric observations on this object. an observing error 0~0.02. 1.
INTRODUCTION
2.
OBSERVATIONS
'IHELIGHT CURVE AND THE PERIOD
From August to November 1982, we used the 60-cm reflector of Xinglong Station, Beijing TABLE 1
V375 Cas is binary. Its
an early-type light curve
is
B Lyrae eclipsing shown in Fig. 1.
V and B-V r!easurements of the Variable, Comparison and Check Stars V
B-V
HD No. magnitude
111. C.
9.94. 10.03 10.20
0.01 0.01 0.01
+62O2332(V) +62”2333 (c)
+62O2331(Ch) *at light maximum
In.C. 0.25. 0.54 1.12
0.01 0.01 0.01
ZHANG, ZHANG et
266
The normal points data are given in TABLE 2. From the figure, we see that the star shows continuous variation outside the eclipses, that the light curve is basically symmetrical, the principal and secondary maxima are nearly minimum is somewhat deep equai, the-secondary and, at the principal minimum, the color index increases slightly, which shows that Component 2 has a lower temperature than The main features of the light Component 1. curve are listed in TABLE 3. TABLE 4 gives the times of the principal and secondary Combining these values of ours with minima. those we collected from the literature, a weighted least-squares reduction gave the new epoch formula as follows:
TABLE 3s Ph.
Normal
tnt.
Points
of
the N
Light
al.
JD He1 . Mini -
2445635”1514 + 1?47338191 X E CI.00000028 f.0016
In this calculation, minimum times obtained photoelectrically were given weight 10, for those obtained photographically, the weights given by Kukarkin [S] were used. The values O-C based on the new epoch formula are given in TABLE 5, and plotted in Fig. 2. From the latter we see that, over nearly 80 the period of this star shows no years, significant changes.
Curve
of
V375 Cas in
Ph.
ht.
the
Yellow
Band N
__ 0.003Y
0.5825
8
0.5093
0.7084
IS
0.0119
0.5Y22
13
0.5195
0.7299
21
U.OlY4
0.6115
7
0.5316
0.7610
18
0.0261
0.6416
8
0.53921
0.7901
Y
0.0323
0.6792
6
0.5469
0.8155
9
0.0483
0.7447
6
0.5571
0.8461
Y
0.0627
0.8029
6
0.5666
0.8744
9
0.0713
0.8443
6
0.5766
0.9075
9
O.OM17
0.8871
6
0.5874
0.9369
9
0.0937
0.9260
6
0.5974
0.9633
9
0.1052
Il.9514
6
0.6128
1.0020
7
0.1193
O.YY70
6
0.6385
1.0290
8
0.1299
1.0119
6
0.6663
1.0515
9
0.1445
1.0283
14
0.6868
1.0806
10
0.17311
1.0497
7
0.7034
1.0923
11
0.1897
1.0670
7
0.7314
1.1028
9
0.2117
1.0748
17
0.7554
1.0970
17
0.2400
1.0920
15
0.7858
1.0813
25
0.2613
1.0934
6
0.8315
1.0452
9
0.2721
1.0974
6
0.8504
1.0303
9
0.2843
1.0982
8
0.8669
0.9983 0.9792
9
0.3067
1.0799
7
0.8894
0.3456
1.0547
11
0.9057
9
0.3855
0.91152
5
0.9261
0.9237 0.8557
0.4223
0.9053
5
0.9371
0.8018
6
0.4327
0.8863
6
0.9463
0.7621
6
0.4435
o.n417
0.7173
6
0.8020
6 Y
0.9567
0.4565
0.9673
0.6669
6
0.4653
21
0.6131
6
27
0.9778 0.9928
0.5856
16
27
0.
i;‘Ji
0.7666 _ U./2M9
IJ.
4Y57
0.7046
6 6
V37.5
TABLZ
3b
267
Cas
Normal Points of the Lieht Curve of
Ph.
int.
0.0062
V375
Cas
in
the 31ue Band
N
Ph.
Int.
0.7236
15
0.5035
0.9228
9 15
N
0.0153
0.7460
9
0.5127
0.9298
O.OZll
0.7791
6
0.5193
0.9475
9
0.0266
0.8072
6
0.5254
0.9655
12
0.0336
0.8484
9
0.5342
1.0052
15
0.0534
0.9913
3
0.5429
1.0430
12
0.0615
1.0306
6
0.5496
1.0670
3
a.0703
1.0833
6
0.5565
1.1086
9
o.onoo
1.1350
6
0.5675
1.1530
12
0.0951
1.2034
9
0.5778
1.1856
6
0.1144
1.2809
9
0.5901
1.2362
15
0.1311
1.3149
9
0.6028
1.2743
6
0.1449
1.3385
9
0.6234
1.3237
9
0.1608
1.3627
6
0.6547
1‘3710
9
0.1840
1.3844
9
0.6818
1.3s3.l
12
0.2027
1.4032
9
0.7039
1.4050
15
0.2196
1.4201
12
0.7559
1.4259
33
0.2561
1.4209
27
0.7969
1.3907
18
0.3142
1.4079
21
0.8414
1.3574
12
0.3675
1.3591
6
0.8596
1.3276
9
0.40x
1.2561
3
0.8773
1.2922
9
0.4256
1.1679
6
0.8908
1.2489
6
1.2105
6
0.4368
1.1269
6
0.9043
0.4489
1.0694
6
0.9167
1.1493
3
0.4583
I.0291
9
0.9316
1.0710
6
0.4631
A.0132
9
0.9404
1.0140
6
0.4689
0.9911
9
0.9502
0.9568
6
0.4751
0.9634
12
0.9606
0.8825
6
0.4531
0.9370
15
0.9713
0.8157
6
0.4Yi7
0.9229
15
0.9819
0.7597
6
0.4993
0.9220
9
0.9939
0.7236
13
268
ZHANG, ZHANG et al.
0.400.30 050
0.40
0.6C
050
I__
___’
I
110
0.5
0
phase Fig.
1
The
Light
curves
TABLE 3 Min
1.
of
V375
Results
of
Min
Il.
Cas
in
BV Cbservations Mar I.
V
1UT64
IO?42
9m94
li
lOf93
IO?67
IO?19
TABIE JO Hel. 2445000+
of Max II. 9m94 lOTl9
0.25
0.33
n-v
BV bands
4
Times
of
rIinima
filter
of
V375 m. c.
.-
210d0803
B
.0824
V
0.0020
V
0.0005
.I249
n
0.0005
265.3291
V
0.0011
235.1235
.3314 266.0680
0.0006
B
0.0004
V
0.0014
.0683
B
0,0011
294.0618
V
0.0014
.0631
B
0.0016
296.2715
u
0.0009
V
0.0006
V
0.0006
.2743 635.149;
Cas
V375
Cas
principal ccl .depth
secondary rcl.depth
om70
Orn48
omi4
Orn48
269
V37S Cas
TABLE 5 JI)
Ilel.
24ulJooo+ _-.36858.5140 28857.7410 29103.8240 29476.5650 31779.4670 31194.3340 34388.8430 34642.2600 35588.1540 36064.09013 4~600.3070 42621.3780 45210.0814 45235.1242 45265.3303 45266.0682 45294.0625 45296.2729 45635.1497
O-C Values of Past Hinina of V375 Gas (0-C)XlO_' (unit:day)
cycle no. E
weight w
(1) (1) (1)
1.0 10.0 3.0 4.0 5.0 3.0 7.0 5.0 2.0 1.0 1.0 1.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0
-15.3 -10.6 17.6 -7.0 -0.9 -6.9 15.7 11.0 -6.2 27.5 12.0 29.3 0.7 -0.4 -2.3 -1.0 -1.0 -0.7 -1.7
-19351.0 -11357.0 -11220.0 -10967.0 -9404.0 -7765.0 -7633.0 -7461.0 -6819.0 -6496.0 -2738.5 -2045.5 -288.5 -271.5 -251.0 -250.5 -231.5 -230.0 0.0
Ref.
(1) (2) (1) (1) (3) (4) (5) (6) (7) (8) (8) (8) (8) (8) (8) (8)
(1) Kukarkina & Novikov. (2) Erleksova. (3) Grigolevskii. (4) Chupina. (5) Satanova. (6) Wood et al. (7) Diethelm. (8) This Paper.
0:03
t
O.OI
Y
0
+
+
O&2 _________..______
..__
CY
i _-
-20000
+ + + _ . ‘__,_ _____-_..- . .._.......------+
t +
+
I
-15CQO
-IcOoO
r-------
L
,
-so00
0
E
Fig. 2
The O-C plot of the minimum time of Q375 Cas. Crosses are photographic, circles are photoelectric observations.The zero line is the first order fit.
ZHANG, ZHANG et
270
TABLE 6
Photometric
al.
Solution
of
V375 Cas B
V5.500~ 0.6848f0.0012 0.239f0.021 0.258f0.065
0.6959f0.0012 0.467f0.016 0.331f0.056 80'53AO.06 0.608*0.004
i
4 = m,lmt Comp. 1 B
1.000*
A
1.000*
TK La r(pole) r(point) r(side) r(back)
4500A
Comp. 2 0.981rtO.015 0.920f0.036 13865f30 3.0781 =Oina 0.3151~0.0012 0.4243jzO.0012 0.3290~0.0015 0.3614f0.0022
17900*
3.2138*0.0081 0.3779*0.0011 0.4498*0.0036 0.3960f0.0014 0.4183f0.0017
QiIln
3.0781** 2.7229*+
Poet
* adopted value. ** theoretical value.
4.
PHOTOMETRICSOLUTION
The measured points of our B and V light curves were combined into 61 and 62 normal points, respectively, with weights proportional to the number of points involved. We used the program package [10,11] based on the Wilson-Devinney method of synthetic light curve to find a solution. We start by assuming the star to be a detached binary, we then use the “Light Curve Program” of the package to attempt an initial solution close to the observed light curve, and then use the “Differential Correction Program” to obtain the final solution. In what follows Component 1 refers to that component which fs eclipsed during the principal eclipse, and Component 2, during the secondary eclipse. In effecting the photometric solution, we fixed the spectral type of V375 Cas at B3, in accordance with Ref. [7]. According to theoretically calculated tables, the surface temperature for a B3 star is 17900 K. Hence we took as initial temperature ~1=17900 K. Also, as initial values, we took the gravity darkening coefficients 91 =q2 =l, surface thermalalbedoesdl =A2 =l, and for the limb; darkening coefficient in B and V, we took The luminosity of the .B=o.41, ,V=o.34. components were calculated by the Planck the adjustformula. Thus, in our solution, able parameters are: the orbital inclination (i), the pole temperature of Component 2 (T2) the surface potentials of the two components of Component 1 (~1) (Ql,Q) 7 the luminosity in the and the mass ratio q=m2/ml. Since,
course of the solution, the result rapidly converged toward the semi-detached configuration, the latter was then used to continue For a set of different with the iteration. values of 4, the corresponding values of c were calculated and we found that Z was the least around q=O.60; we then adjusted the other parameters 91, 92, Al, AZ, x1, x2 and finally derived that c is a minimum at The variation of c withgis shown q= 0.608. in Fig. 3. X ‘1.5.1.U
0.5-
9
Fig.
3
The z - 9 diagram
of
V37S Cas
The final results of the photometric solution are given in TABLE 6. From these, we see that V375 Cas is a semi-detached system, in which Component 2 (the less massive one) fills
V375 Cas
completely the critical potential surface while Component 1 (the more massive one) nearly does so. See Fig. 4.
271
REFERENCES
Weber, R., L'astronomie 69 (1955) 440. Solob'ev A.V., Astron.Tsir. 176 (1957) Grigolevskii V.M., Perem.Zvezdy 12 [31 (1959) v. 2, 149. ]41 Churpina R., Perem.Zvezdy 12 (1959) v.2 152. Kikarkin B.V., Novikov, I.D., Perem. t51 Zvezdy 13 (1960) v. 5, 366. [61 Satanova E.A., Perem.Zvezdy 13 (1960) v. 2 128. Brodskaya E.S., Isv.Krym.Astr.0b.s. 14 [71 Fig. 4 Configuration of V375 Cas (1955). Wood, F.B. et al, A Finding List for [81 Observers of Interacting Binary Stars, 1980. 5. DISCUSSION Diethelm, R., Bull, D., Bedeckungs Ver. [91 Boeb.d.SchweizerischenAst.Gesselschft. ~375 Cas is an early-type, semi-detached 23 (1976). binary system. The small mass component completely fills its Roche lobe and the large DOI wilson,R.E., Devinney, E.J., Ap.J.166 (1971) 605. mass component nearly does so. In its contact configuration, it is very similar to t111 Leung, K.C., Schneider, D.P., Ap.J.222 (1978) 917. AI Cru [12], BV Eri [13] and RZ Dra [14]. These all have mass ratios around 0.5. We WI Russo,R., Astrophysics & Space Science 77 (1981) 197. are unable to determine its position on the H-R diagram, due to the lack of radial veloc1131 Baade, Duerbeck, H.W., Darimie, M.T., and Yamasaki, A., Astrophysics & Space ity data; but from the present available Science 93 (1983) 69. results, its seems that V375 Cas belongs to Leung, K.C., ZHAI Di-sheng, HUANG Yinthe evolutionary stage of an Algol star after P41 liang, Chin.Astron.Astrophys. 6 (1982) the mass reversal, and, this being so, further 199-204 = Act.Astrophys.Sin.2 (1982) study of this star will be important for 144-151. our understanding of the evolution of earlytype close binaries.
;:;
ACKNOWLEDGEMENT We thank Colleague JIANG Zhao-ji for assistance in realising the computer program.