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Photometry and the determination of oscillation modes for high amplitude Delta Scuti (HADS) variable GSC 1566-2802
New Astronomy 37 (2015) 76–80
Contents lists available at ScienceDirect
New Astronomy journal homepage: www.elsevier.com/locate/newast
Photometry and the determination of oscillation modes for high amplitude Delta Scuti (HADS) variable GSC 1566-2802 E. Salmanzadeh a,⇑, S. Zandian a, A. Hasanzadeh a,b,c, S. Zahabi a a
The International Occultation Timing Association-Middle East Section (IOTA-ME), Iran Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P.O. Box: 55134-441, Maragha, Iran c Institutes of Geophysics, University of Tehran, Tehran, Iran b
h i g h l i g h t s We presented the analysis of photometric observation of GSC 1566-2802 in the visible filter. We improved the ephemeris for times of maximum. The Fourier analysis has been performed and obtained oscillation modes. The physical parameters were calculated according to the main period.
a r t i c l e
i n f o
Article history: Received 5 November 2014 Accepted 13 December 2014 Available online 23 December 2014 Communicated by P.S. Conti Keywords: Variable star Delta Scuti Oscillation mode Photometry observation
a b s t r a c t CCD photometry observation of a newly discovered, high amplitude Delta Scuti star GSC 1566-2802, with a visible filter, is presented. The observations were carried out at Alborz Observatory located in Mahdasht, Karaj, Iran. The main goal of this project was to update our knowledge of the periodic variations of the target star. This paper covers three analyses, first calculating a new ephemeris and plotting a new light curve based on 19 times of maxima; then a Fourier analysis of the observed data points which results in determining probable oscillation modes, as well as computing its physical parameters which guide us to its harmonics and pulsation modes. Ó 2014 Elsevier B.V. All rights reserved.
1. Introduction Pulsating stars play an important role in probing the physical properties of stars, including their masses, luminosities, temperatures and metallicities. Pulsating stars cover a broad range of stellar parameters and evolutionary stages (Derekas et al., 2009). Based upon this importance, the Hipparcos mission discovered a large number of new variable stars including a number of Delta Scuti stars (Perryman, 1997). Delta Scuti (DSCT) stars are short period pulsating variables (about 0.01 to 0.2 days) situated in the extension of the Cepheid instability strip, which crosses the main sequence between A2 and F0 (Baglin et al., 1973); they display light amplitudes ranging from a few thousandths to a few tenths of a magnitude in the visual region of the spectrum (Percy, 2007).
High amplitude Delta Scuti star variables (HADS) are late A and early F type pulsating stars that vary in light and radial velocity in periods of one to six hours with an amplitude greater than 0.2 mag (Breger and Montgomery, 2000). GSC 1566-2802 is a high amplitude (HADS) short period pulsating star with a period of 0.060465324 days. The magnitude range of this star is between 13.0 and 13.6 in a visible filter (Variable Star Index, 2014). The variable nature of GSC 1566-2802 was discovered by Edgar Wunder from Germany in 2013 while mining data from the Northern Sky Variability Survey (Wunder, 2013).
2. Observation and data reduction
⇑ Corresponding author. E-mail addresses: [email protected] (E. Salmanzadeh), hasanzadeh@ iota-me.com (A. Hasanzadeh). http://dx.doi.org/10.1016/j.newast.2014.12.005 1384-1076/Ó 2014 Elsevier B.V. All rights reserved.
Owing to the fact that this star has a short period and high amplitude, it is a very good target for small and moderates sized telescopes, such that interesting astrophysical phenomena can be easily studied even with modest instrumentation.
77
E. Salmanzadeh et al. / New Astronomy 37 (2015) 76–80
The CCD photometry of GSC 1566-2802 was carried out at Alborz Observatory in a clear sky condition on July 3, 2012. The observatory coordinates are 50° 470 08.7700 East and 35° 450 52.7300 North. Equipment used to make these observations included an SBIG 11000 CCD camera with 2004 1336 pixels and a 40 cm LX200 Meade Schmidt Cassegrain telescope with a focal reducer operating at f/10. The camera control and image calibration were performed using Maxim DL software. The CCD observations were reduced in Maxim DL 5.2, including bias and dark removal and flat-field correction. The exposure times for main and dark images were 30 s and 5 s for the flat image. According to the paper by Wunder (2013) and two observation reports about this variable star (Ayiomamitis, 2013; Paschalis, 2013) GSC1566-3377 was chosen as the comparison star, while another close star, GSC 1566-2912, in the same field of view was chosen as check star (Fig. 1; Table 1). Magnitudes were calculated with aperture photometry using comparison and the check star. Fig. 1. One of the CCD images of GSC 1566-2802 was obtained using the 40 cm LX200 Meade Schmidt Cassegrain telescope at Alborz Observatory. The stars GSC 1566-3377and GSC 1566-2912 were selected as comparison and reference stars, respectively.
Table 1 Coordinates and magnitudes of GSC 1566-2802, the comparison and the check stars. Stars
Name
Magnitude (V)
RA
Dec
Variable
GSC 15662802 GSC 15663377 GSC 15662912
13.0–13.6
18 h 02 m 52 s 18 h 02 m 54 s 18 h 02 m 40 s
+21 310 5400 +21 300 2600
Comparison Check
12.8 11.0
+21 300 5700
3. Data analysis The aim of this work was to perform an extensive study of light period variation. The bad data points of the light curve are visually inspected and removed during the data reduction process. Table 2 Our calculated times of maxima.
1 2 3 4
HJD (Max)
Error (days)
2456477.30175 2456477.36095 2456477.42360 2456477.48378
0.00049 0.00051 0.00063 0.00082
Fig. 2. CCD photometric light curve of GSC 1566-2802 in V band was observed on July 3, 2012. Dots in the top part of the graph refer to magnitude differences between GSC 1566-2802 and the comparison star; in the bottom part they refer to the magnitude of the comparison star. In the second diagram the dots represent the magnitude of the check star.
78
E. Salmanzadeh et al. / New Astronomy 37 (2015) 76–80
Table 3 Previous CCD times of maximum (Wunder, 2013): These data gathered by The Northern Sky Variability Survey (NSVS), a temporal record of the sky over the optical magnitude range from 8 to 15.5 as a public data base and The All Sky Automated Survey (ASAS), a Polish project implemented on 7 April 1997 to conduct photometric monitoring of approximately 20 million stars brighter than 14th magnitude. Data source
HJD (Max)
Data source
HJD (Max)
Data source
HJD (Max)
NSVS NSVS ASAS ASAS ASAS
2451323.902 2451427.720 2452841.700 2453490.796 2453848.814
ASAS ASAS Wunder Wunder Wunder
2454257.681 2454646.653 2456157.3792 2456157.4399 2456158.3459
Wunder Wunder Wunder Wunder Wunder
2456158.4069 2456167.3549 2456167.4145 2456175.3371 2456187.3072
Then the light curves of the main star and the check star relative to the comparison star were obtained. The top part of Fig. 2 shows that the light curves of GSC 1566-2802 and the magnitude of the check star are observed at the bottom of this figure. Heliocentric corrections were made to the Julian dates (JD) of the light curve. To obtain maxima times, we divided our light curves into four sections and fitted the best 4th degree polynomial function for each part. The result of this analysis gives four times of maxima (Table 2), clearly shown in Fig. 2 (top part). For the sake of our goal which is to calculate a new ephemeris and the oscillation modes, the two following sections are presented.
3.1. New ephemeris To calculate a new ephemeris, maxima times of the star are needed. The only published data belongs to Wunder, where 15 times of maxima are recounted (Table 3). The linear ephemeris equation of GSC 1566-2802 was determined to be (Wunder, 2013)
HJDðMaxÞ ¼ 2456157:3785 þ 0:060465324 E
Fig. 3. The fitted diagram according to maximum time to calculate the ephemeris.
ð1Þ
The period of the star was defined as T = t0 + P E according to the ephemeris, where we used this relation to predict the star’s next times of maxima. In the equation, T is the first observe maximum time, P is the star’s main period and E is the number of passed periods or complete oscillations from the epoch t0. According to all the maxima collected, the following fitted diagram was derived (Fig. 3).
Fig. 4. Fourier extension of the light curve.
Fig. 5. Differential light curve with the three-frequency fitted curves (solid lines) using Period4.
E. Salmanzadeh et al. / New Astronomy 37 (2015) 76–80
to the high amplitude features of the star, we used the most recent collaboration which was presented by McNamara (2011) as
Table 4 Principle frequencies (three oscillation modes).
1 2 3
79
Frequency (cycles/day)
Amplitude (magnitude)
16.478 33.134 49.326
0.259 0.096 0.037
MV ¼ ð2:89 0:13Þ log P ð1:31 0:10Þ
ð3Þ
where P is expressed in days. By using the above relation the absolute magnitude of the star in a visible filter was calculated as Mv = 2.13 ± 0.31 Based upon the empirical period-luminosity relation of McNamara (2011) the color index (B–V) of the star is calculated as
B—V ¼ ð0:105 0:004Þ log P þ ð0:336 0:005Þ
ð4Þ
So the amount of B–V is 0.211 ± 0.010. Based on physical evolution of Delta Scuti variable stars, the effective temperature and bolometric correction of the star extracted from Table 3 of Flower (1996) is: T = 7707 ± 59 K and BC = 0.033 ± 0.001. These results assure us that the star’s spectral class is in A7 as mentioned in the introduction. By using the bolometric magnitude definition Mbol ¼ M V þ BC (5), Mbol is 2.16 ± 0.31 magnitude. Masses M of Delta Scuti stars (in solar masses M ) can be calculated from the relation (Cox 1999):
log M ¼ 0:46 0:1Mbol
Fig. 6. The position of GSC1566-2802 on the H–R diagram based on the models offered by Christensen-Dalsgaard (1993).
ð5Þ
The mass of the star would be calculated as M ¼ ð1:75 0:12ÞM . In order to estimate the radius of the star, the star’s luminosity is needed which can be calculated as ð11:066 3:202ÞL leading to the radius of the star being about ð11:88 0:24ÞR . According to the obtained values, the position of the star in the H–R diagram based on the models offered by ChristensenDalsgaard (1993) is shown in Fig. 6. 5. Conclusion
Based on 19 times of maxima light in the v band, a new ephemeris were improved as
Maxðhel:Þ ¼ 2456157:37895ð0:00033Þ þ 0:060465333ð0:000000010Þ E
ð2Þ
3.2. Calculating oscillation modes The period analysis has been performed by means of standard Fourier analysis and least squares fitting. In particular, the amplitude of the differential time series was obtained by means of the Period 04 package (Lenz and Breger, 2005). This computer package allows all the frequencies to fit simultaneously in the magnitude domain. Based on the intensity and the best fitted curve in Figs. 4 and 5, three principle frequencies are suggested in Table 4. Based on Fig. 4 two maxima are apparent. At first we chose two main frequencies; then we used Period04 in order on fit a curve on our data points. The data failed to fit properly on the curve so we then three main frequencies and were able to derive a better fitted diagram. The result is shown in Fig. 5. 4. Physical parameters The variable nature of the star, according to what we observed, is important in astronomy because high amplitude Delta Scuti type variables can be used as standard reference points. Therefore calculations of galactic distances are possible. By using the main period, we can calculate Mv, B–V, Mbol, L, .... In order to obtain these global parameters the following relations were used. According
According to the collected data and light curves an improved ephemeris for GSC 1566-2802 which is a newly discovered Delta Scuti star, is proposed. A new amplitude is also calculated as 0.060465333 days with a rank error of 108. Finally the main modes were studied and three principle frequencies were represented as 16.4779, 33.1341 and 49.3265 cycle/day for GSC 15662802. The values of the global parameters (Mbol ¼ 2:243 mag, L ¼ 11:066L , R ¼ 1:88R , M ¼ 1:75M , T ¼ 7707 K) compare well with the ranges for Delta Scuti star which agree with our results. Although there is a deficiency of spectroscopy in this project our photometry result is another step helping understand the variable feature of this star. Further study however, is needed. Acknowledgments This work has been supported financially by the Research Institute for Astronomy & Astrophysics of Maragha (RIAAM) under research project No. 1/3720-65, Iranian Space Agency and IOTA/ ME. Special thanks to Mr. Atila Poro, head of IOTA/ME and also thanks to Paul D. Maley for checking the manuscript. References Ayiomamitis, A., 2013. Perseus observatory.. Baglin, A., Breger, M., Chevalier, C., et al., 1973. A&A 23, 221. Breger, M., Montgomery, M.H., 2000. APS Conf. Ser. 210, 3. Cox, A.N., 1999. Allen’s Astrophysical Quantities, fourth ed. AIP Press, Springer. Christensen-Dalsgaard, J., 1993. ASPC 40, 483. Derekas, A., Kiss, L.L., Székely, P., et al., 2009. MNRAS 394, 995. Flower, P.J., 1996. ApJ 469, 355. Lenz, P., Breger, M., 2005. CoAst 146, 53. McNamara, D.H., 2011. AJ 142, 110. Paschalis, N., 2013. .
80
E. Salmanzadeh et al. / New Astronomy 37 (2015) 76–80
Percy, J.R., 2007. Understanding Variable Stars, first ed. Cambridge University Press, New York. Perryman, M.A.C., European Space Agency Space Science Department, and the Hipparcos Science Team,1997. The Hipparcos and Tycho Catalogues, ESA SP1200, ESA Publications Division. Noordwijk, The Netherlands.
Variable Star Index, 2014.. Wunder, E., 2013. BAV Rundbrief 1, 14.
Contents lists available at ScienceDirect
New Astronomy journal homepage: www.elsevier.com/locate/newast
Photometry and the determination of oscillation modes for high amplitude Delta Scuti (HADS) variable GSC 1566-2802 E. Salmanzadeh a,⇑, S. Zandian a, A. Hasanzadeh a,b,c, S. Zahabi a a
The International Occultation Timing Association-Middle East Section (IOTA-ME), Iran Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P.O. Box: 55134-441, Maragha, Iran c Institutes of Geophysics, University of Tehran, Tehran, Iran b
h i g h l i g h t s We presented the analysis of photometric observation of GSC 1566-2802 in the visible filter. We improved the ephemeris for times of maximum. The Fourier analysis has been performed and obtained oscillation modes. The physical parameters were calculated according to the main period.
a r t i c l e
i n f o
Article history: Received 5 November 2014 Accepted 13 December 2014 Available online 23 December 2014 Communicated by P.S. Conti Keywords: Variable star Delta Scuti Oscillation mode Photometry observation
a b s t r a c t CCD photometry observation of a newly discovered, high amplitude Delta Scuti star GSC 1566-2802, with a visible filter, is presented. The observations were carried out at Alborz Observatory located in Mahdasht, Karaj, Iran. The main goal of this project was to update our knowledge of the periodic variations of the target star. This paper covers three analyses, first calculating a new ephemeris and plotting a new light curve based on 19 times of maxima; then a Fourier analysis of the observed data points which results in determining probable oscillation modes, as well as computing its physical parameters which guide us to its harmonics and pulsation modes. Ó 2014 Elsevier B.V. All rights reserved.
1. Introduction Pulsating stars play an important role in probing the physical properties of stars, including their masses, luminosities, temperatures and metallicities. Pulsating stars cover a broad range of stellar parameters and evolutionary stages (Derekas et al., 2009). Based upon this importance, the Hipparcos mission discovered a large number of new variable stars including a number of Delta Scuti stars (Perryman, 1997). Delta Scuti (DSCT) stars are short period pulsating variables (about 0.01 to 0.2 days) situated in the extension of the Cepheid instability strip, which crosses the main sequence between A2 and F0 (Baglin et al., 1973); they display light amplitudes ranging from a few thousandths to a few tenths of a magnitude in the visual region of the spectrum (Percy, 2007).
High amplitude Delta Scuti star variables (HADS) are late A and early F type pulsating stars that vary in light and radial velocity in periods of one to six hours with an amplitude greater than 0.2 mag (Breger and Montgomery, 2000). GSC 1566-2802 is a high amplitude (HADS) short period pulsating star with a period of 0.060465324 days. The magnitude range of this star is between 13.0 and 13.6 in a visible filter (Variable Star Index, 2014). The variable nature of GSC 1566-2802 was discovered by Edgar Wunder from Germany in 2013 while mining data from the Northern Sky Variability Survey (Wunder, 2013).
2. Observation and data reduction
⇑ Corresponding author. E-mail addresses: [email protected] (E. Salmanzadeh), hasanzadeh@ iota-me.com (A. Hasanzadeh). http://dx.doi.org/10.1016/j.newast.2014.12.005 1384-1076/Ó 2014 Elsevier B.V. All rights reserved.
Owing to the fact that this star has a short period and high amplitude, it is a very good target for small and moderates sized telescopes, such that interesting astrophysical phenomena can be easily studied even with modest instrumentation.
77
E. Salmanzadeh et al. / New Astronomy 37 (2015) 76–80
The CCD photometry of GSC 1566-2802 was carried out at Alborz Observatory in a clear sky condition on July 3, 2012. The observatory coordinates are 50° 470 08.7700 East and 35° 450 52.7300 North. Equipment used to make these observations included an SBIG 11000 CCD camera with 2004 1336 pixels and a 40 cm LX200 Meade Schmidt Cassegrain telescope with a focal reducer operating at f/10. The camera control and image calibration were performed using Maxim DL software. The CCD observations were reduced in Maxim DL 5.2, including bias and dark removal and flat-field correction. The exposure times for main and dark images were 30 s and 5 s for the flat image. According to the paper by Wunder (2013) and two observation reports about this variable star (Ayiomamitis, 2013; Paschalis, 2013) GSC1566-3377 was chosen as the comparison star, while another close star, GSC 1566-2912, in the same field of view was chosen as check star (Fig. 1; Table 1). Magnitudes were calculated with aperture photometry using comparison and the check star. Fig. 1. One of the CCD images of GSC 1566-2802 was obtained using the 40 cm LX200 Meade Schmidt Cassegrain telescope at Alborz Observatory. The stars GSC 1566-3377and GSC 1566-2912 were selected as comparison and reference stars, respectively.
Table 1 Coordinates and magnitudes of GSC 1566-2802, the comparison and the check stars. Stars
Name
Magnitude (V)
RA
Dec
Variable
GSC 15662802 GSC 15663377 GSC 15662912
13.0–13.6
18 h 02 m 52 s 18 h 02 m 54 s 18 h 02 m 40 s
+21 310 5400 +21 300 2600
Comparison Check
12.8 11.0
+21 300 5700
3. Data analysis The aim of this work was to perform an extensive study of light period variation. The bad data points of the light curve are visually inspected and removed during the data reduction process. Table 2 Our calculated times of maxima.
1 2 3 4
HJD (Max)
Error (days)
2456477.30175 2456477.36095 2456477.42360 2456477.48378
0.00049 0.00051 0.00063 0.00082
Fig. 2. CCD photometric light curve of GSC 1566-2802 in V band was observed on July 3, 2012. Dots in the top part of the graph refer to magnitude differences between GSC 1566-2802 and the comparison star; in the bottom part they refer to the magnitude of the comparison star. In the second diagram the dots represent the magnitude of the check star.
78
E. Salmanzadeh et al. / New Astronomy 37 (2015) 76–80
Table 3 Previous CCD times of maximum (Wunder, 2013): These data gathered by The Northern Sky Variability Survey (NSVS), a temporal record of the sky over the optical magnitude range from 8 to 15.5 as a public data base and The All Sky Automated Survey (ASAS), a Polish project implemented on 7 April 1997 to conduct photometric monitoring of approximately 20 million stars brighter than 14th magnitude. Data source
HJD (Max)
Data source
HJD (Max)
Data source
HJD (Max)
NSVS NSVS ASAS ASAS ASAS
2451323.902 2451427.720 2452841.700 2453490.796 2453848.814
ASAS ASAS Wunder Wunder Wunder
2454257.681 2454646.653 2456157.3792 2456157.4399 2456158.3459
Wunder Wunder Wunder Wunder Wunder
2456158.4069 2456167.3549 2456167.4145 2456175.3371 2456187.3072
Then the light curves of the main star and the check star relative to the comparison star were obtained. The top part of Fig. 2 shows that the light curves of GSC 1566-2802 and the magnitude of the check star are observed at the bottom of this figure. Heliocentric corrections were made to the Julian dates (JD) of the light curve. To obtain maxima times, we divided our light curves into four sections and fitted the best 4th degree polynomial function for each part. The result of this analysis gives four times of maxima (Table 2), clearly shown in Fig. 2 (top part). For the sake of our goal which is to calculate a new ephemeris and the oscillation modes, the two following sections are presented.
3.1. New ephemeris To calculate a new ephemeris, maxima times of the star are needed. The only published data belongs to Wunder, where 15 times of maxima are recounted (Table 3). The linear ephemeris equation of GSC 1566-2802 was determined to be (Wunder, 2013)
HJDðMaxÞ ¼ 2456157:3785 þ 0:060465324 E
Fig. 3. The fitted diagram according to maximum time to calculate the ephemeris.
ð1Þ
The period of the star was defined as T = t0 + P E according to the ephemeris, where we used this relation to predict the star’s next times of maxima. In the equation, T is the first observe maximum time, P is the star’s main period and E is the number of passed periods or complete oscillations from the epoch t0. According to all the maxima collected, the following fitted diagram was derived (Fig. 3).
Fig. 4. Fourier extension of the light curve.
Fig. 5. Differential light curve with the three-frequency fitted curves (solid lines) using Period4.
E. Salmanzadeh et al. / New Astronomy 37 (2015) 76–80
to the high amplitude features of the star, we used the most recent collaboration which was presented by McNamara (2011) as
Table 4 Principle frequencies (three oscillation modes).
1 2 3
79
Frequency (cycles/day)
Amplitude (magnitude)
16.478 33.134 49.326
0.259 0.096 0.037
MV ¼ ð2:89 0:13Þ log P ð1:31 0:10Þ
ð3Þ
where P is expressed in days. By using the above relation the absolute magnitude of the star in a visible filter was calculated as Mv = 2.13 ± 0.31 Based upon the empirical period-luminosity relation of McNamara (2011) the color index (B–V) of the star is calculated as
B—V ¼ ð0:105 0:004Þ log P þ ð0:336 0:005Þ
ð4Þ
So the amount of B–V is 0.211 ± 0.010. Based on physical evolution of Delta Scuti variable stars, the effective temperature and bolometric correction of the star extracted from Table 3 of Flower (1996) is: T = 7707 ± 59 K and BC = 0.033 ± 0.001. These results assure us that the star’s spectral class is in A7 as mentioned in the introduction. By using the bolometric magnitude definition Mbol ¼ M V þ BC (5), Mbol is 2.16 ± 0.31 magnitude. Masses M of Delta Scuti stars (in solar masses M ) can be calculated from the relation (Cox 1999):
log M ¼ 0:46 0:1Mbol
Fig. 6. The position of GSC1566-2802 on the H–R diagram based on the models offered by Christensen-Dalsgaard (1993).
ð5Þ
The mass of the star would be calculated as M ¼ ð1:75 0:12ÞM . In order to estimate the radius of the star, the star’s luminosity is needed which can be calculated as ð11:066 3:202ÞL leading to the radius of the star being about ð11:88 0:24ÞR . According to the obtained values, the position of the star in the H–R diagram based on the models offered by ChristensenDalsgaard (1993) is shown in Fig. 6. 5. Conclusion
Based on 19 times of maxima light in the v band, a new ephemeris were improved as
Maxðhel:Þ ¼ 2456157:37895ð0:00033Þ þ 0:060465333ð0:000000010Þ E
ð2Þ
3.2. Calculating oscillation modes The period analysis has been performed by means of standard Fourier analysis and least squares fitting. In particular, the amplitude of the differential time series was obtained by means of the Period 04 package (Lenz and Breger, 2005). This computer package allows all the frequencies to fit simultaneously in the magnitude domain. Based on the intensity and the best fitted curve in Figs. 4 and 5, three principle frequencies are suggested in Table 4. Based on Fig. 4 two maxima are apparent. At first we chose two main frequencies; then we used Period04 in order on fit a curve on our data points. The data failed to fit properly on the curve so we then three main frequencies and were able to derive a better fitted diagram. The result is shown in Fig. 5. 4. Physical parameters The variable nature of the star, according to what we observed, is important in astronomy because high amplitude Delta Scuti type variables can be used as standard reference points. Therefore calculations of galactic distances are possible. By using the main period, we can calculate Mv, B–V, Mbol, L, .... In order to obtain these global parameters the following relations were used. According
According to the collected data and light curves an improved ephemeris for GSC 1566-2802 which is a newly discovered Delta Scuti star, is proposed. A new amplitude is also calculated as 0.060465333 days with a rank error of 108. Finally the main modes were studied and three principle frequencies were represented as 16.4779, 33.1341 and 49.3265 cycle/day for GSC 15662802. The values of the global parameters (Mbol ¼ 2:243 mag, L ¼ 11:066L , R ¼ 1:88R , M ¼ 1:75M , T ¼ 7707 K) compare well with the ranges for Delta Scuti star which agree with our results. Although there is a deficiency of spectroscopy in this project our photometry result is another step helping understand the variable feature of this star. Further study however, is needed. Acknowledgments This work has been supported financially by the Research Institute for Astronomy & Astrophysics of Maragha (RIAAM) under research project No. 1/3720-65, Iranian Space Agency and IOTA/ ME. Special thanks to Mr. Atila Poro, head of IOTA/ME and also thanks to Paul D. Maley for checking the manuscript. References Ayiomamitis, A., 2013. Perseus observatory.
80
E. Salmanzadeh et al. / New Astronomy 37 (2015) 76–80
Percy, J.R., 2007. Understanding Variable Stars, first ed. Cambridge University Press, New York. Perryman, M.A.C., European Space Agency Space Science Department, and the Hipparcos Science Team,1997. The Hipparcos and Tycho Catalogues, ESA SP1200, ESA Publications Division. Noordwijk, The Netherlands.
Variable Star Index, 2014.