464 results on '"Esamdin, A."'
Search Results
152. Flare Properties of A-type Stars in Kepler Data
- Author
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Bai, Jian-Ying, primary and Esamdin, Ali, additional
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- 2020
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153. The GRANDMA network in preparation for the fourth gravitational-wave observing run
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Adler, David S., Seaman, Robert L., Benn, Chris R., Agayeva, S., Aivazyan, V., Alishov, S., Almualla, M., Andrade, C., Antier, Sarah, Bai, J. M., Baransky, A., Basa, S., Bendjoya, P., Benkhaldoun, Z., Beradze, S., Berezin, D., Bhardwaj, U., Blazek, M., Burkhonov, O., Burns, E., Caudill, S., Christensen, N., Colas, F., Coleiro, A., Corradi, W., Coughlin, M. W., Culino, T., Darson, D., Datashvili, D., de Wasseige, G., Dietrich, T., Dolon, F., Dornic, D., Dubouil, J., Ducoin, J.-G., Duverne, P.-A., Esamdin, A., Fouad, A., Guo, F., Godunova, V., Gokuldass, P., Guessoum, N., Gurbanov, E., Hainich, R., Hasanov, E., Hello, P., Hussenot-Desenonges, T., Inasaridze, R., Iskandar, A., Ishida, E.E.O., Ismailov, N., Jegou du Laz, T., Kann, D.A., Kapanadze, G., Karpov, S., Kiendrebeogo, R.W., Klotz, A., Kochiashvili, N., Kaeouach, A., Kneib, J.-P., Kou, W., Kruiswijk, K., Lombardo, S., Lamoureux, M., Leroy, N., Le Van Su, A., Mao, J., Masek, M., Midavaine, T., Moeller, A., Morris, D., Natsvlishvili, R., Navarete, F., Nissanke, S., Noonan, K., Noysena, K., Orange, N.B., Peloton, J., Pilloix, M., Pradier, T., Prouza, M., Raaijmakers, G., Rajabov, Y., Rivet, J.-P., Romanyuk, Y., Rousselot, L., Ruenger, F., Rupchandani, V., Sadibekova, T., Sasaki, N., Simon, A., Smith, K., Sokoliuk, O., Song, X., Takey, A., Tillayev, Y., Tosta e Melo, I., Turpin, D., de Ugarte Postigo, A., Vardosanidze, M., Wang, X.F., Vernet, D., Vidadi, Z., Zhu, J., and Zhu, Y.
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- 2022
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154. SN 2017fgc: A Fast-expanding Type Ia Supernova Exploded in Massive Shell Galaxy NGC 474
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Jujia Zhang, Jun Mo, Jicheng Zhang, C. Pellegrino, D. Andrew Howell, Griffin Hosseinzadeh, Hanna Sai, Ali Esamdin, Mengfan Zhang, Han Lin, Abdusamatjan Iskandar, Tianmeng Zhang, Alexei V. Filippenko, David J. Sand, Timothy W. Ross, Xiaofeng Wang, Jialian Liu, Thomas G. Brink, Shuo Ma, Benjamin E. Stahl, Daichi Hiramatsu, Wenxiong Li, Lifan Wang, WeiKang Zheng, Benjamin T. Jeffers, Curtis McCully, Danfeng Xiang, Stefano Valenti, Gaobo Xi, Daniel E. Reichart, Peng Wei, Xiangyun Zeng, Samantha Stegman, and Jamison Burke
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Brightness ,Metallicity ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Light curve ,Spectral line ,Galaxy ,Luminosity ,Supernova ,Space and Planetary Science ,Astrophysics - High Energy Astrophysical Phenomena ,Ejecta - Abstract
We present extensive optical photometric and spectroscopic observations of the high-velocity (HV) Type Ia supernova (SN Ia) 2017fgc, covering the phase from $\sim$ 12 d before to $\sim 389$ d after maximum brightness. SN 2017fgc is similar to normal SNe Ia, with an absolute peak magnitude of $M_{\rm max}^{B} \approx$ $-19.32 \pm 0.13$ mag and a post-peak decline of ${\Delta}m_{15}(B)$ = $1.05 \pm 0.07$ mag. Its peak bolometric luminosity is derived as $1.32 \pm 0.13) \times 10^{43} $erg s$^{-1}$, corresponding to a $^{56}$Ni mass of $0.51 \pm 0.03 M_{\odot}$. The light curves of SN 2017fgc are found to exhibit excess emission in the $UBV$ bands in the early nebular phase and pronounced secondary shoulder/maximum features in the $RrIi$ bands. Its spectral evolution is similar to that of HV SNe Ia, with a maximum-light Si II velocity of $15,000 \pm 150 $km s$^{-1}$ and a post-peak velocity gradient of $\sim$ $120 \pm 10 $km s$^{-1} $d$^{-1}$. The Fe II and Mg II lines blended near 4300 {\AA} and the Fe II, Si II, and Fe III lines blended near 4800 {\AA} are obviously stronger than those of normal SNe Ia. Inspecting a large sample reveals that the strength of the two blends in the spectra, and the secondary peak in the $i/r$-band light curves, are found to be positively correlated with the maximum-light Si II velocity. Such correlations indicate that HV SNe~Ia may experience more complete burning in the ejecta and/or that their progenitors have higher metallicity. Examining the birthplace environment of SN 2017fgc suggests that it likely arose from a stellar environment with young and high-metallicity populations., Comment: 30 pages, 21 figures, 5 tables
- Published
- 2021
155. A mathematical method for the de-dispersion of the pulsar profile
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Yuan, JianPing, Wang, Na, Wu, XinJi, and Esamdin, Ali
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- 2010
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156. Site-testing at Muztagh-ata site III: temperature inversion in surface-layer atmosphere
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Xu, Jing, primary, Esamdin, Ali, additional, Feng, Guo-Jie, additional, Pu, Guang-Xin, additional, Hu, Yi, additional, Hu, Ke-Liang, additional, Yang, Xu, additional, Hao, Jin-Xin, additional, Xue, Yan-Jie, additional, Zhou, Xu, additional, Ma, Shu-Guo, additional, Yisikandee, Abudusaimaitijiang, additional, Wang, Le-Tian, additional, Zhang, Xuan, additional, Bai, Chun-Hai, additional, Wei, Peng, additional, Ming, Liang, additional, Ma, Lu, additional, Liu, Jin-Zhong, additional, and Jiang, Yun-Ying, additional
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- 2020
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157. Long-term analysis of clear nights using satellite data considering astronomical sites in western China
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Cao, Zi-Huang, primary, Liu, Li-Yong, additional, Zhao, Yong-Heng, additional, Feng, Lu, additional, Jones, Hugh R. A., additional, Shen, Huang, additional, Hao, Jin-Xin, additional, Xue, Yan-Jie, additional, Yao, Yong-Qiang, additional, Xu, Jing, additional, Esamdin, Ali, additional, Qi, Zhao-Xiang, additional, Shi, Jian-Rong, additional, Li, Jian, additional, Tian, Yuan, additional, Wang, Zheng, additional, Yan, Tai-Sheng, additional, Wang, Xia, additional, Xiong, Jian-Ping, additional, Yu, Si-Cheng, additional, Zhang, Jun-Bo, additional, Shen, Zhi-Xia, additional, Jiang, Yun-Ying, additional, Yin, Jia, additional, Pu, Guang-Xin, additional, Wei, Peng, additional, Bai, Chun-Hai, additional, Feng, Guo-Jie, additional, Ma, Lu, additional, Song, Teng-Fei, additional, Wang, Jian-Feng, additional, Tian, Jian-Feng, additional, Zeng, Xian-Qun, additional, Hou, Zhi-Gang, additional, Liao, Shi-Long, additional, Cao, Zhi-Song, additional, Fan, Dong-Wei, additional, Xu, Yun-Fei, additional, Li, Chang-Hua, additional, and Tao, Yi-Han, additional
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- 2020
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158. Site testing at Muztagh-ata site II: seeing statistics
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Xu, Jing, primary, Esamdin, Ali, additional, Hao, Jin-Xin, additional, Bai, Jin-Min, additional, Yang, Ji, additional, Zhou, Xu, additional, Yao, Yong-Qiang, additional, Hou, Jin-Liang, additional, Pu, Guang-Xin, additional, Feng, Guo-Jie, additional, Bai, Chun-Hai, additional, Wei, Peng, additional, Ma, Shu-Guo, additional, Yisikandee, Abudusaimaitijiang, additional, Wang, Le-Tian, additional, Zhang, Xuan, additional, Ming, Liang, additional, Ma, Lu, additional, Liu, Jin-Zhong, additional, Cao, Zi-Huang, additional, Zhao, Yong-Heng, additional, Feng, Lu, additional, Shi, Jian-Rong, additional, Chen, Hua-Lin, additional, Pei, Chong, additional, Jiang, Xiao-Jun, additional, Wang, Jian-Feng, additional, Tian, Jian-Feng, additional, Xue, Yan-Jie, additional, Hu, Jing-Yao, additional, and Jiang, Yun-Ying, additional
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- 2020
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159. Site testing campaign for the Large Optical/infrared Telescope of China: overview
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Feng, Lu, primary, Hao, Jin-Xin, additional, Cao, Zi-Huang, additional, Bai, Jin-Min, additional, Yang, J, additional, Zhou, Xu, additional, Yao, Yong-Qiang, additional, Hou, Jin-Liang, additional, Zhao, Yong-Heng, additional, Liu, Yu, additional, Song, Teng-Fei, additional, Liu, Li-Yong, additional, Yin, Jia, additional, Chen, Hua-Lin, additional, Pei, Chong, additional, Esamdin, Ali, additional, Ma, Lu, additional, Bai, Chun-Hai, additional, Wei, Peng, additional, Xu, Jing, additional, Pu, Guang-Xin, additional, Feng, Guo-Jie, additional, Zhang, Xuan, additional, Ming, Liang, additional, Yisikandee, Abudusaimaitijiang, additional, Shi, Jian-Rong, additional, Li, Jian, additional, Tian, Yuan, additional, Wang, Zheng, additional, Wang, Xia, additional, Jiang, Xiao-Jun, additional, Wang, Jian-Feng, additional, Tian, Jian-Feng, additional, Xue, Yan-Jie, additional, Chen, Jian-Sheng, additional, Hu, Jing-Yao, additional, Shen, Zhi-Xia, additional, and Jiang, Yun-Ying, additional
- Published
- 2020
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160. Data processing and data products from 2017 to 2019 campaign of astronomical site testing at Ali, Daocheng and Muztagh-ata
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Cao, Zi-Huang, primary, Hao, Jin-Xin, additional, Feng, Lu, additional, Jones, Hugh R. A., additional, Li, Jian, additional, Xu, Jing, additional, Liu, Li-Yong, additional, Song, Teng-Fei, additional, Wang, Jian-Feng, additional, Chen, Hua-Lin, additional, Xue, Yan-Jie, additional, Shen, Huang, additional, Zhao, Yong-Heng, additional, Qi, Zhao-Xiang, additional, Shi, Jian-Rong, additional, Tian, Yuan, additional, Wang, Zheng, additional, Wang, Xia, additional, Hou, Jin-Liang, additional, Bai, Jin-Ming, additional, Yang, Ji, additional, Zhou, Xu, additional, Yao, Yong-Qiang, additional, Yin, Jia, additional, Esamdin, Ali, additional, Pu, Guang-Xin, additional, Wei, Peng, additional, Bai, Chun-Hai, additional, Feng, Guo-Jie, additional, Ma, Lu, additional, Zhang, Xuan, additional, Liu, Yu, additional, Pei, Chong, additional, Shen, Zhi-Xia, additional, Jiang, Yun-Ying, additional, Tian, Jian-Feng, additional, Zeng, Xian-Qun, additional, Hou, Zhi-Gang, additional, Yang, Xu, additional, Zhang, Jun-Bo, additional, Liao, Shi-Long, additional, Fan, Dong-Wei, additional, Xu, Yun-Fei, additional, Xiong, Jian-Ping, additional, Yan, Tai-Sheng, additional, Zhang, Xi, additional, Li, Chang-Hua, additional, Tao, Yi-Han, additional, Yu, Si-Cheng, additional, Cao, Zhi-Song, additional, and Wang, Hong-Shuai, additional
- Published
- 2020
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161. Site-testing at Muztagh-ata site I: ground meteorology and sky brightness
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Xu, Jing, primary, Esamdin, Ali, additional, Hao, Jin-Xin, additional, Bai, Jin-Min, additional, Yang, Ji, additional, Zhou, Xu, additional, Yao, Yong-Qiang, additional, Hou, Jin-Liang, additional, Pu, Guang-Xin, additional, Feng, Guo-Jie, additional, Bai, Chun-Hai, additional, Wei, Peng, additional, Ma, Shu-Guo, additional, Yisikandee, Abudusaimaitijiang, additional, Wang, Le-Tian, additional, Zhang, Xuan, additional, Ming, Liang, additional, Ma, Lu, additional, Liu, Jin-Zhong, additional, Cao, Zi-Huang, additional, Zhao, Yong-Heng, additional, Feng, Lu, additional, Shi, Jian-Rong, additional, Chen, Hua-Lin, additional, Pei, Chong, additional, Jiang, Xiao-Jun, additional, Wang, Jian-Feng, additional, Tian, Jian-Feng, additional, Xue, Yan-Jie, additional, Hu, Jing-Yao, additional, and Jiang, Yun-Ying, additional
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- 2020
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162. A double-modulation effect detected in a double-mode high-amplitude $\delta$ Scuti star: KIC 10284901
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Ali Esamdin and Taozhi Yang
- Subjects
Physics ,Modulation effect ,High amplitude ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Mode (statistics) ,Astronomy and Astrophysics ,Astrophysics ,Star (graph theory) - Abstract
In this paper, we present an analysis of the pulsating behavior of $Kepler$ target KIC 10284901. The Fourier transform of the high-precision light curve reveals seven independent frequencies for its light variations. Among them, the first two frequencies are main pulsation modes: F0 = 18.994054(1) $\rm{day^{-1}}$ and F1 = 24.335804(4) $\rm{day^{-1}}$, the ratio of F0/F1 = 0.7805 classifies this star as a double-mode high-amplitude $\delta$ Scuti (HADS) star; another two frequencies, $f_{m1}$ = 0.4407 day$^{-1}$ and $f_{m2}$ = 0.8125 day$^{-1}$, are detected directly, and the modulations of $f_{m1}$ and $f_{m2}$ to F0 and F1 modes (seen as quintuplet structures centered on these two modes in the frequency spectrum) are also found. This is the first detection of a double-modulation effect in the HADS stars. The features of the frequency pattern and the ratio ($f_{m1}$/$f_{m2}$ $\approx$ 1:2), as well as the cyclic variation of amplitude of the two dominant pulsation modes, which seem to be similar to that in Blazhko RR Lyrae stars, indicate this modulation might be related to the Blazhko effect. A preliminary analysis suggests that KIC 10284901 is in the bottom of the HADS instability strip and situated in the main sequence., Comment: 9 pages,4 figures, 2 tables, published by ApJ on 5 July,2019
- Published
- 2019
163. Precise determination of stellar parameters of the ZZ Ceti and DAZ white dwarf GD 133 through asteroseismology
- Author
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C. Li, Hubiao Niu, N. Dolez, L. Fox Machado, Jian-Ning Fu, Hui-Fang Xue, Yan Li, G. Vauclair, S. L. Kim, Ali Esamdin, Jie Su, Raul Michel, Lu Ma, M. Alvarez, Jinzhong Liu, T. Q. Cang, François Colas, Xiao-Jun Jiang, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Rotation period ,Physics ,Planetesimal ,010308 nuclear & particles physics ,FOS: Physical sciences ,stars:evolution ,White dwarf ,Astronomy and Astrophysics ,Gravitational interaction ,Astrophysics ,01 natural sciences ,Asteroseismology ,Astrophysics - Solar and Stellar Astrophysics ,[SDU]Sciences of the Universe [physics] ,Space and Planetary Science ,Planet ,0103 physical sciences ,Tidal force ,stars: individual: GD 133 ,stars: oscillations ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,white dwarfs - Abstract
An increasing number of white dwarf stars show atmospheric chemical composition polluted by heavy elements accreted from debris disk material. The existence of such debris disks strongly suggests the presence of one or more planet(s) whose gravitational interaction with rocky planetesimals is responsible for their disruption by tidal effect. The ZZ Ceti pulsator and polluted DAZ white dwarf GD 133 is a good candidate for searching for such a potential planet. We started in 2011 a photometric follow-up of its pulsations. As a result of this work in progress, we used the data gathered from 2011 to 2015 to make an asteroseismological analysis of GD 133, providing the star parameters from a best fit model with $M$/$M_{\odot}$ = 0.630 $\pm$ 0.002, $T_{\rm eff}$ = 12400 K $\pm$ 70 K, log($M_{\rm He}/M$) = -2.00 $\pm$ 0.02, log($M_{\rm H}/M$) = -4.50 $\pm$ 0.02 and determining a rotation period of $\approx$ 7 days., 10 pages, 13 figures, accepted by MNRAS
- Published
- 2019
164. Qatar Exoplanet Survey: Qatar-8b, 9b, and 10b—A Hot Saturn and Two Hot Jupiters
- Author
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Alsubai, K., Tsvetanov, Z., Pyrzas, S., Latham, D., Bieryla, A., Eastman, J., Mislis, D., Esquerdo, G., Southworth, J., Mancini, L., Esamdin, A., Liu, J., Ma, L., Bretton, M., Pallé, E., Murgas, F., Vilchez, N., Parviainien, H., Montañes-Rodriguez, P., Narita, N., Fukui, A., Kusakabe, N., Tamura, M., Barkaoui, K., Pozuelos, F., Gillon, M., Jehin, E., Benkhaldoun, Z., and Daassou, A.
- Abstract
In this paper we present three new extrasolar planets from the Qatar Exoplanet Survey. Qatar-8b is a hot Saturn, with M P = 0.37 M J and R P = 1.3 R J, orbiting a solar- like star every P orb = 3.7 days. Qatar-9b is a hot Jupiter with a mass of M P = 1.2 M J and a radius of R P = 1 R J, in an orbit of P orb = 1.5 days around a low mass, M ⋆ = 0.7 M ☉, mid-K main- sequence star. Finally, Qatar-10b is a hot, T eq ∼ 2000 K, sub-Jupiter mass planet, M P = 0.7 M J, with a radius of R P = 1.54 R J and an orbital period of P orb = 1.6 days, placing it on the edge of the sub-Jupiter desert.
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- 2019
165. Investigating variable stars in the open cluster NGC 1912 and its surrounding field
- Author
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Chun-Yan Li, Ali Esamdin, Yu Zhang, Fang-Fang Song, Xiang-Yun Zeng, Li Chen, Hu-Biao Niu, Jian-Ying Bai, and Jun-Hui Liu
- Subjects
Space and Planetary Science ,Astronomy and Astrophysics - Published
- 2021
166. Investigating variable stars in the open cluster NGC 1912 and its surrounding field
- Author
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Junhui Liu, J. M. Bai, Yu Zhang, Chun-Yan Li, Li Chen, Ali Esamdin, Hubiao Niu, Xiangyun Zeng, and Fangfang Song
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Physics ,010308 nuclear & particles physics ,Diagram ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Star (graph theory) ,Light curve ,Astrophysics - Astrophysics of Galaxies ,01 natural sciences ,Variable (computer science) ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,0103 physical sciences ,Cluster (physics) ,Variable star ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Open cluster - Abstract
In this work, we studied the variable stars in the open cluster NGC 1912 based on the photometric observations and $Gaia$ DR2 data. More than 3600 CCD frames in B, V, R filters were reduced, and we obtained the light curves that span about 63 hours. By analyzing these light curves, we detected 24 variable stars, including 16 periodic variable stars, seven eclipsing binaries and one star whose type is unclear. Among these 24 variable stars, 11 are newly-discovered, which are classified as six gamma Doradus stars, one delta Scuti star, three detached binaries and one contact binaries. We also confirmed 13 previously known variable stars. Based on cluster members identified by Cantat-Gaudin et al. (2018), we inferred cluster memberships for these detected variable stars. Using Gaia DR2 data, we plotted a new color-magnitude diagram for NGC 1912, and showed the nature of variable cluster members in kinematical properties and heliocentric distance. Among the 24 variable stars, seven variables are probable cluster members, which show homogeneity in kinematic characters and space position with the established cluster members. Four of the seven variable cluster members are the previously discovered stars, consisting of two gamma Dor stars and two delta Sct stars. The remaining three variable cluster members, which are all gamma Dor stars, are firstly detected in this work. The main physical parameters of these variable cluster members estimated from the color-magnitude diagram are log(age/yr)=8.75, [Fe/H]=-0.1, m-M=10.03 mag, and E(B-V)=0.307., Comment: 27 pages, 20 figure, 4 table
- Published
- 2021
167. State-switching Mechanism of Intermittent Pulsars
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Abdujappar Rusul, Xiao-Ping Zheng, Ali Esamdin, Liang Guo, and Li-Xin Xia
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Physics ,Neutron star ,Pulsar ,Space and Planetary Science ,Astrophysics::High Energy Astrophysical Phenomena ,State switching ,Astronomy and Astrophysics ,Astrophysics ,Mechanism (sociology) - Abstract
The emission feature of intermittent pulsars is significant for understanding the pulsar emission mechanism. Using the observational evidence of radio emissions turning on and off and the corresponding spin-down rates in these two states of an intermittent pulsar, we will examine the polar-cap potential drop, gap height, and curvature radii of a few intermittent pulsars within the regime of the pulsar polar-cap emission theory by applying the current loss and energy flux of particle flow to pulsar braking, which are generally associated with radio emission from the polar cap. It is seen that the polar-cap parameters of the intermittent pulsars are almost equal to their maximum values, which is the main prediction of the pulsar polar-cap theory with respect to the breaking of the radio emission. It is also noticed that the intermittent pulsars are distributed near the dipole death line in the diagram, which is consistent with their emission features and the calculated polar-cap parameters. To further confirm the state switching of the intermittent pulsar, the relationships among spin-down rate, gap height, potential drop, and activity duty cycles of PSR B1931+24 are discussed. It is found that the gap height has an anticorrelation with the activity duty cycle, which indicates that the intermittency of the radio emission has a close connection to the gap height, as indicated by the pulsar polar-cap emission theory.
- Published
- 2021
168. The Observation of Pulsars at Urumqi Astronomical Observatory
- Author
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Wu, Xinji, primary, Wang, Na, additional, Zhang, Jin, additional, Esamdin, Ali, additional, Manchester, R. N., additional, Cheng, K. S., additional, Lyne, A. G., additional, Yusup, Aili, additional, Zhang, Hongbo, additional, Kang, Liansen, additional, and Jin, Shenzen, additional
- Published
- 2000
- Full Text
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169. Flare Properties of A-type Stars in Kepler Data
- Author
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Ali Esamdin and J. M. Bai
- Subjects
Physics ,Space and Planetary Science ,law ,Astronomy and Astrophysics ,Astrophysics ,A-type main-sequence star ,Kepler ,Flare ,law.invention - Abstract
We analyzed the long-cadence (LC) light curves of 5435 stars with effective temperatures of 7000–10,500 K in Data Release 25 of Kepler to extend the samples of A-type flare stars and study their flare properties. A total of 103 flare stars are detected, of which 72 have the Large Sky Area Multi-Object fiber Spectroscopic Telescope spectral types, resulting in 51 A-type stars, including 17 new and 34 known. A total of 352 flares are detected from the 51 stars. The flare durations, amplitudes, and energies in the Kepler band are calculated, with medians of 2.5 hr, 2.1 mmag, and 1035.8 erg, respectively. We give the flare frequency distribution (FFD) of the A-type stars. Within the same energy range, the flare rates of our FFD are lower than those in previous research, which was also based on Kepler LC data, and the FFD slope is consistent with that in the research. The activity–rotation relation of the A-type flare stars is shown for the first time, in which the flare activity decreases as the rotation period increases. The relation is similar to that of the late-type stars in previous studies. For the two relatively bright A-type flare stars, KIC 5360548 and KIC 9468475, three high-resolution spectra are observed on different nights for each of them, and radial velocities are calculated and compared with that of the previous research. The comparisons suggest that there is no evidence of the KIC 5360548 companion, and KIC 9468475 could have a low-mass companion.
- Published
- 2020
170. The wide-field photometric system of the Nanshan One-meter Telescope
- Author
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Lu Ma, Abdusamatjan Eskandar, Jinzhong Liu, X. Zhang, Shu-Guo Ma, Chun-Hai Bai, Guo-Jie Feng, Ali Esamdin, Hubiao Niu, Na Wang, Guang-Xin Pu, and Xiao-Jun Jiang
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Physics ,010308 nuclear & particles physics ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy ,Photometric system ,Astronomy and Astrophysics ,Field of view ,Astrophysics ,01 natural sciences ,law.invention ,Telescope ,Stars ,Space and Planetary Science ,law ,0103 physical sciences ,Calibration ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Focus (optics) ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,010303 astronomy & astrophysics ,Noise (radio) ,Dark current - Abstract
The Nanshan One-meter Wide-field Telescope (NOWT) is a prime focus system located at Nanshan Station of Xinjiang Astronomical Observatories (XAO). The field of view(FOV) was designed to 1.5 degree *1.5 degree, and Johnson-Cousins UBVRI system was chosen as the main Filter set. The telescope has been providing observation services for astronomers since Sept. 2013. Variable source searching and time-domain surveys are the main scientific goals. The system's test results are reported including linearity, dark current, bias, readout noise and gain of the CCD camera. The accurate instrumental calibration coefficients in UBVRI bands was driven with Landolt standard stars during photometric nights. Finally, the limiting magnitudes are given with signal-to-noise ratios and various exposure times for observers., Comment: 11 pages, 14 figures, 8tables
- Published
- 2020
171. Data processing and data products from 2017 to 2019 campaign of astronomical site testing at Ali, Daocheng and Muztagh-ata
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Yongqiang Yao, Yunfei Xu, Zheng Wang, Hong-Shuai Wang, Zhaoxiang Qi, Chun-Hai Bai, Jian-Feng Wang, Jin-Ming Bai, Hua-Lin Chen, Yong-Heng Zhao, Jianrong Shi, Zhi-Gang Hou, Xia Wang, Yan-Jie Xue, Yun-Ying Jiang, Hugh R. A. Jones, Dongwei Fan, Yuan Tian, Zihuang Cao, Xu Yang, Huang Shen, Xuan Zhang, Jin-Xin Hao, Jian-Ping Xiong, Xi Zhang, Jin-Liang Hou, Si-Cheng Yu, Li-Yong Liu, Yihan Tao, Jian Li, Ali Esamdin, Zeng Xianqun, Tai-Sheng Yan, Jia Yin, Jian-Feng Tian, Xu Zhou, Shilong Liao, Zhi-Xia Shen, Changhua Li, Chong Pei, Ji Yang, Jing Xu, Lu Ma, Yu Liu, Peng Wei, Guo-Jie Feng, Lu Feng, Jun-Bo Zhang, Zhi-Song Cao, Guang-Xin Pu, and Teng-Fei Song
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Physics ,Data processing ,Data products ,010308 nuclear & particles physics ,Space and Planetary Science ,Site testing ,0103 physical sciences ,Site selection ,Library science ,Astronomy and Astrophysics ,Astrophysics ,010303 astronomy & astrophysics ,01 natural sciences - Abstract
Based on previous site testing and satellite cloud data, Ali, Daocheng and Muztagh-ata have been selected as candidate sites for the Large Optical/Infrared Telescope (LOT) in China. We present the data collection, processing, management and quality analysis for our site testing based on using similar hardware. We analyze meteorological data, seeing, background light, cloud and precipitable water vapor data from 2017 March 10 to 2019 March 10. We also investigated the relative usefulness of our all-sky camera data in comparison to that from the meteorological TERRA satellite data based on a night-by-night comparison of the correlation and consistency between them.We find a 6% discrepancy arising from a wide range of factors.
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- 2020
172. Site-testing at Muztagh-ata site I: ground meteorology and sky brightness
- Author
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Guang-Xin Pu, Jing-Yao Hu, Yongqiang Yao, Jin-Min Bai, Chong Pei, Zihuang Cao, Le-Tian Wang, Shu-Guo Ma, Jian-Feng Tian, Ali Esamdin, Yan-Jie Xue, Jian-Feng Wang, Jinzhong Liu, Jinliang Hou, Yun-Ying Jiang, Yongheng Zhao, Ji Yang, Abudusaimaitijiang Yisikandee, Guo-Jie Feng, Xu Zhou, Hua-Lin Chen, Chun-Hai Bai, Jin-Xin Hao, Peng Wei, Jianrong Shi, Lu Ma, Jing Xu, Xiao-Jun Jiang, Lu Feng, X. Zhang, and Liang Ming
- Subjects
Physics ,geography ,Plateau ,geography.geographical_feature_category ,Automatic weather station ,Meteorology ,010308 nuclear & particles physics ,Site testing ,Infrared telescope ,FOS: Physical sciences ,Astronomy and Astrophysics ,01 natural sciences ,Wind speed ,Space and Planetary Science ,Sky brightness ,Air temperature ,0103 physical sciences ,Relative humidity ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,010303 astronomy & astrophysics - Abstract
Site-testing is crucial for achieving the goal of scientific research and analysis of meteorological and optical observing conditions is one of the basic tasks of it. As one of three potential sites to host 12-meter Large Optical/infrared Telescope (LOT), Muztagh-ata site which is located on the Pamirs Plateau in west China's Xinjiang began its site-testing task in the spring of 2017. In this paper, we firstly start with an introduction to the site and then present a statistical analysis of the ground-level meteorological properties such as air temperature, barometric pressure, relative humidity, wind speed and direction, recorded by automatic weather station with standard meteorological sensors for two-year long. We also show the monitoring results of sky brightness during this period., 16 pages, 19 figures
- Published
- 2020
173. Site testing campaign for the Large Optical/infrared Telescope of China: overview
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Xiao-Jun Jiang, Hua-Lin Chen, Chun-Hai Bai, Jin-Xin Hao, Chong Pei, Jiansheng Chen, Yan-Jie Xue, Jianrong Shi, Jian Li, Jinliang Hou, Tengfei Song, Yongqiang Yao, Zhi-Xia Shen, Lu Feng, Peng Wei, Yongheng Zhao, Guang-Xin Pu, Ali Esamdin, Guo-Jie Feng, Jian-Feng Wang, Yu Liu, Yuan Tian, Zihuang Cao, Jing Xu, Abudusaimaitijiang Yisikandee, Jing-Yao Hu, Xia Wang, Ji Yang, Liang Ming, Zheng Wang, Li-Yong Liu, Jia Yin, Jin-Min Bai, Lu Ma, X. Zhang, Jian-Feng Tian, Xu Zhou, and Yun-Ying Jiang
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Physics ,010308 nuclear & particles physics ,Site testing ,Infrared telescope ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,Space and Planetary Science ,Satellite remote sensing ,0103 physical sciences ,Performance monitoring ,Astrophysics - Instrumentation and Methods for Astrophysics ,China ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,010303 astronomy & astrophysics ,Remote sensing - Abstract
The Large Optical/infrared Telescope (LOT) is a ground-based 12 m diameter optical/infrared telescope which is proposed to be built in the western part of China in the next decade. Based on satellite remote sensing data, along with geographical, logistical and political considerations, three candidate sites were chosen for ground-based astronomical performance monitoring. These sites include: Ali in Tibet, Daocheng in Sichuan and Muztagh-ata in Xinjiang. Up until now, all three sites have continuously collected data for two years. In this paper, we will introduce this site testing campaign, and present its monitoring results obtained during the period between March 2017 and March 2019.
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- 2020
174. Site-testing at Muztagh-ata site III: temperature inversion in surface-layer atmosphere
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Lu Ma, Guo-Jie Feng, Chun-Hai Bai, Liang Ming, Shu-Guo Ma, Xu Zhou, Guang-Xin Pu, X. Zhang, Le-Tian Wang, Yi Hu, Yun-Ying Jiang, Ke-Liang Hu, Yan-Jie Xue, Jing Xu, Xu Yang, Ali Esamdin, Jin-Xin Hao, Abudusaimaitijiang Yisikandee, Jinzhong Liu, and Peng Wei
- Subjects
Atmosphere ,Physics ,Space and Planetary Science ,Site testing ,Astronomy and Astrophysics ,Atmospheric turbulence ,Astrophysics ,Surface layer ,Atmospheric sciences - Abstract
In this article, we present detailed seasonal, monthly and daily statistics of temperature difference in the surface layer at the Muztagh-ata site based on the temperature measurements at two heights of 2m and 6m. We find that temperature inversion occurs frequently at our site during nighttime, especially during the cold season. Strong temperature inversion always represents stable atmospheric turbulence, which is crucial for an optical observatory. By analyzing the behavior of temperature inversion and its correlation with wind and cloud amount, one conclusion can be made that radiation inversion is the main reason for the existence of temperature inversion in the surface-layer at the Muztagh-ata site.
- Published
- 2020
175. Long-term analysis of clear nights using satellite data considering astronomical sites in western China
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Peng Wei, Jian-Feng Tian, Chun-Hai Bai, Jianrong Shi, Guo-Jie Feng, Huang Shen, Guang-Xin Pu, Zhi-Song Cao, Jun-Bo Zhang, Hugh R. A. Jones, Zihuang Cao, Zeng Xianqun, Xia Wang, Yihan Tao, Changhua Li, Ali Esamdin, Jian-Feng Wang, Lu Ma, Jian Li, Yuan Tian, Si-Cheng Yu, Zheng Wang, Zhi-Gang Hou, Lu Feng, Yun-Ying Jiang, Li-Yong Liu, Jia Yin, Jian-Ping Xiong, Yan-Jie Xue, Yong-Heng Zhao, Zhi-Xia Shen, Zhaoxiang Qi, Jing Xu, Shilong Liao, Dongwei Fan, Jin-Xin Hao, Yongqiang Yao, Yunfei Xu, Teng-Fei Song, and Tai-Sheng Yan
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Physics ,Methods statistical ,Space and Planetary Science ,Satellite data ,Site testing ,Climatology ,Astronomy and Astrophysics ,Astrophysics ,China ,Term (time) - Abstract
A large ground-based optical/infrared telescope is being planned for a world-class astronomical site in China. The cloud-free night percentage is the primary meteorological consideration for evaluating candidate sites. The data from GMS and NOAA satellites and the MODIS instrument were utilized in this research, covering the period from 1996 to 2015. Our data analysis benefits from overlapping results from different independent teams as well as a uniform analysis of selected sites using GMS+NOAA data. Although significant ground-based monitoring is needed to validate these findings, we identify three different geographical regions with a high percentage of cloud-free conditions (∼83% on average), which is slightly lower than at Mauna Kea and Cerro Armazones (∼85% on average) and were chosen for the large international projects TMT and ELT respectively. Our study finds evidence that cloud distributions and the seasonal changes affected by the prevailing westerly winds and summer monsoons reduce the cloud cover in areas influenced by the westerlies. This is consistent with the expectations from climate change models and is suggestive that most of the identified sites will have reduced cloud cover in the future.
- Published
- 2020
176. Second Braking Index of Intermittent Pulsar and Nulling Pulsar
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Liang Guo, Xiao-Ping Zheng, Ali Esamdin, and Abdujappar Rusul
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Physics ,Index (economics) ,Pulsar ,Space and Planetary Science ,Astronomy and Astrophysics ,Neutron ,Astrophysics - Published
- 2020
177. A Weak Modulation Effect Detected in the Light Curves of KIC 5950759: Intrinsic or Instrumental Effect?
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Guo-Jie Feng, Jinzhong Liu, Fei Zhao, Xiangyun Zeng, Junhui Liu, Fangfang Song, Peng Zong, Taozhi Yang, Lu Ma, Hubiao Niu, and Ali Esamdin
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Physics ,010308 nuclear & particles physics ,Star (game theory) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Rotation ,Light curve ,01 natural sciences ,Amplitude modulation ,symbols.namesake ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Fourier analysis ,0103 physical sciences ,Modulation (music) ,symbols ,Atomic physics ,Instability strip ,Cadence ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
In this paper, the high-precision light curves of $Kepler$ target KIC 5950759 are analyzed. The Fourier analysis of the long cadence light curve reveals 3 independent frequencies. Two of them are main pulsation modes: F0 = 14.221373(21) $\rm{d^{-1}}$ and F1 = 18.337249(44) $\rm{d^{-1}}$. The third independent frequency $f_m$ = 0.3193 d$^{-1}$ is found in long cadence data with a signal-to-noise ratio of 6.2. A weak modulation of $f_m$ to F0 and F1 modes (triplet structures centred on F0 and F1) are detected both in long and short cadence data. This is the first detection of the modulation effect in a double-mode HADS star. The most possible cause of the modulation effect in the light curves is amplitude modulation with the star's rotation frequency of 0.3193 d$^{-1}$. The preliminary analysis suggests that KIC 5950759 is in the bottom of the HADS instability strip and likely situated in the main sequence. Spectroscopic observations are necessary to verify the true nature of the modulation terms., 10 pages, 7 figures. Published in ApJ (on 2018 August 23)
- Published
- 2018
178. A precursive study of the time-domain survey of the Galactic Anti-center using the Nanshan 1-meter telescope with variable stars detected
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Yu Zhang, Ali Esamdin, Fangfang Song, Shu-Guo Ma, Taozhi Yang, Hubiao Niu, Jinzhong Liu, Lu Ma, Guang-Xin Pu, and Jian-Ning Fu
- Subjects
Physics ,010504 meteorology & atmospheric sciences ,media_common.quotation_subject ,Center (category theory) ,Astronomy and Astrophysics ,Astrophysics ,Light curve ,01 natural sciences ,LAMOST ,law.invention ,Telescope ,Space and Planetary Science ,Sky ,law ,0103 physical sciences ,Binary star ,Variable star ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Data reduction ,media_common - Abstract
Following the LAMOST Spectroscopic Survey and the Xuyi’s Photometric Survey of the Galactic Anti-center, we plan to carry out a time-domain survey of the Galactic Anti-center (TDS-GAC) to study variable stars by using the Nanshan 1-meter telescope. Before the beginning of TDS-GAC, a precursive sky survey (PSS) has been executed. The goal of the PSS is to optimize the observation strategy of TDS-GAC and to detect some strong transient events, as well as to find some short time-scale variable stars of different types. By observing a discontinuous sky area of $15.03~\mbox{deg}^{2}$ with the standard Johnson-Cousin-Bessel $V$ filter, 48 variable stars are found and the time series are analyzed. Based on the behaviors of the light curves, 28 eclipsing binary stars, 10 RR Lyraes, 3 periodic pulsating variables of other types have been classified. The rest 7 variables stay unclassified with deficient data. In addition, the observation strategy of TD-GAC is described, and the pipeline of data reduction is tested.
- Published
- 2018
179. Qatar Exoplanet Survey: Qatar-7b -- A Very Hot Jupiter Orbiting a Metal Rich F-Star
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David W. Latham, Akihiko Fukui, Pilar Montañés-Rodríguez, Allyson Bieryla, S. Pyrzas, Zlatan Tsvetanov, Nobuhiko Kusakabe, Dimitris Mislis, Gilbert A. Esquerdo, Timothy D. Morton, Felipe Murgas, M. Bretton, Motohide Tamura, Lu Ma, Khalid Al-Subai, Norio Narita, N. Vilchez, Hannu Parviainien, Enric Palle, Jinzhong Liu, and Ali Esamdin
- Subjects
010504 meteorology & atmospheric sciences ,Gas giant ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Planet ,0103 physical sciences ,Hot Jupiter ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Astronomy and Astrophysics ,Radius ,Planetary system ,Orbital period ,Exoplanet ,Radial velocity ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present the discovery of Qatar-7b --- a very hot and inflated giant gas planet orbiting close its parent star. The host star is a relatively massive main sequence F-star with mass and radius Mstar = 1.41 +/- 0.03 Msun and Rstar = 1.56 +/- 0.02 Rsun, respectively, at a distance d = 726 +/- 26 pc, and an estimated age ~1 Gyr. With its orbital period of P = 2.032 days the planet is located less than 5 stellar radii from its host star and is heated to a high temperature Teq ~ 2100 K. From a global solution to the available photometric and radial velocity observations, we calculate the mass and radius of the planet to be Mpl = 1.88 +/- 0.25 Mjup and Rpl = 1.70 +/- 0.03 Rjup, respectively. The planet radius and equilibrium temperature put Qatar-7b in the top 6% of the hottest and largest known exoplanets. With its large radius and high temperature Qatar-7b is a valuable addition to the short list of targets that offer the best opportunity for studying their atmospheres through transmission spectroscopy.
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- 2018
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180. An Optical and X-Ray Study of the Contact Binary, BH Cassiopeiae
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Liu, Junhui, primary, Esamdin, Ali, additional, Zhang, Yu, additional, Hu, Chin-Ping, additional, Chen, Tingting, additional, Zhang, Junbo, additional, Liu, Jinzhong, additional, Li, Zixi, additional, Ren, Juanjuan, additional, Zheng, Jie, additional, Niu, Hubiao, additional, Bai, Chunhai, additional, and Ge, Liang, additional
- Published
- 2019
- Full Text
- View/download PDF
181. A Double-modulation Effect Detected in a Double-mode High-amplitude δ Scuti Star: KIC 10284901
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Yang, Tao-Zhi, primary and Esamdin, Ali, additional
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- 2019
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- View/download PDF
182. Qatar Exoplanet Survey: Qatar-8b, 9b, and 10b—A Hot Saturn and Two Hot Jupiters
- Author
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Alsubai, Khalid, primary, Tsvetanov, Zlatan I., additional, Pyrzas, Stylianos, additional, Latham, David W., additional, Bieryla, Allyson, additional, Eastman, Jason, additional, Mislis, Dimitris, additional, Esquerdo, Gilbert A., additional, Southworth, John, additional, Mancini, Luigi, additional, Esamdin, Ali, additional, Liu, Jinzhong, additional, Ma, Lu, additional, Bretton, Marc, additional, Pallé, Enric, additional, Murgas, Felipe, additional, Vilchez, Nicolas P. E., additional, Parviainien, Hannu, additional, Montañes-Rodriguez, Pilar, additional, Narita, Norio, additional, Fukui, Akihiko, additional, Kusakabe, Nobuhiko, additional, Tamura, Motohide, additional, Barkaoui, Khalid, additional, Pozuelos, Francisco, additional, Gillon, Michael, additional, Jehin, Emmanuel, additional, Benkhaldoun, Zouhair, additional, and Daassou, Ahmed, additional
- Published
- 2019
- Full Text
- View/download PDF
183. Pulsations of the SX Phe Star BL Camelopardalis
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Zong, Peng, primary, Esamdin, Ali, additional, Fu, Jian Ning, additional, Niu, Hu Biao, additional, Feng, Guo Jie, additional, Yang, Tao Zhi, additional, Bai, Chun Hai, additional, Zhang, Yu, additional, and Liu, Jin Zhong, additional
- Published
- 2019
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- View/download PDF
184. Precise determination of stellar parameters of the ZZ Ceti and DAZ white dwarf GD 133 through asteroseismology
- Author
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Fu, J-N, primary, Vauclair, G, additional, Su, J, additional, Fox Machado, L, additional, Colas, F, additional, Kim, S-L, additional, Cang, T Q, additional, Li, C, additional, Niu, H B, additional, Xue, H F, additional, Li, Y, additional, Jiang, X-J, additional, Michel, R, additional, Alvarez, M, additional, Dolez, N, additional, Ma, L, additional, Esamdin, A, additional, and Liu, J Z, additional
- Published
- 2019
- Full Text
- View/download PDF
185. Qatar Exoplanet Survey: Qatar-7b—A Very Hot Jupiter Orbiting a Metal-rich F-Star
- Author
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Alsubai, Khalid, primary, Tsvetanov, Zlatan I., additional, Latham, David W., additional, Bieryla, Allyson, additional, Pyrzas, Stylianos, additional, Mislis, Dimitris, additional, Esquerdo, Gilbert A., additional, Esamdin, Ali, additional, Liu, Jinzhong, additional, Ma, Lu, additional, Bretton, Marc, additional, Pallé, Enric, additional, Murgas, Felipe, additional, Vilchez, Nicolas P. E., additional, Morton, Timothy D., additional, Parviainien, Hannu, additional, Montañes-Rodriguez, Pilar, additional, Narita, Norio, additional, Fukui, Akihiko, additional, Kusakabe, Nobuhiko, additional, and Tamura, Motohide, additional
- Published
- 2019
- Full Text
- View/download PDF
186. Time-domain survey of the Galactic anti-center using Nanshan 1m telescope
- Author
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J.-N. Fu, Ali Esamdin, L. Ma, Fangfang Song, Taozhi Yang, and Jinzhong Liu
- Subjects
Telescope ,Physics ,Space and Planetary Science ,law ,Astronomy ,Astronomy and Astrophysics ,Center (algebra and category theory) ,Time domain ,law.invention - Abstract
Following the LAMOST Spectroscopic Survey and Xuyi's Photometric Survey of the Galactic anti-center (GAC), we plan to conduct a time-domain survey of GAC to study the variable sky using Nanshan 1m telescope. The survey will be conducted during winter (in Nov., Dec., and Jan.). The first goal of the survey is to cover 270 sq.deg. of sky area in three years. The survey intends to detect some strong transient events of stars and find some short time-scale variable stars of different types. In this paper, we introduce the survey and present the preliminary results already carried out.
- Published
- 2015
187. Pulsations of the High-Amplitude $\delta$ Scuti Star YZ Bootis
- Author
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Yang, Taozhi, Esamdin, Ali, Fu, Jianning, Niu, Hubiao, Feng, Guojie, Song, Fangfang, Liu, Jinzhong, and Ma, Lu
- Subjects
Astrophysics - Solar and Stellar Astrophysics - Abstract
We present a study on the pulsations of the high-amplitude $\delta$ Scuti star YZ Boo based on photometric observations in Johnson $V$ and $R$ bands with both the Nanshan 1-m telescope of Xinjiang Astronomical Observatory (XAO) and the Xinglong 85-cm telescope of National Astronomical Observatories, Chinese Academy of Sciences (NAOC). The Fourier analysis of the light curves reveals the fundamental radial mode and its five harmonics, with the fourth and the fifth newly detected. 39 new times of light maximum are determined from the light curves, and combined with those in the literature, we construct the $O - C$ diagram and derive a new ephemeris and the determination of a new value of the updated period 0.104091579(2). Besides, the $O - C$ diagram reveals an increasing period change rate of YZ Boo. Theoretical models are calculated and constrained with the observationally determined parameters of YZ Boo. The mass and age of YZ Boo are hence derived as $M$ = 1.61 $\pm$ 0.05 $M_\odot$ and $age$ = (1.44 $\pm$ 0.14) $\times$ 10$^9$ yr, respectively. With both the frequency of the fundamental radial mode and the period change rate, YZ Boo is located at the post-main-sequence stage., Comment: 12 pages, 6figures
- Published
- 2017
188. Predicting the Braking Indices of Nulling and Intermittent Pulsars
- Author
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Ali Esamdin, Abdujappar Rusul, and Xiao-Ping Zheng
- Subjects
Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Magnetosphere ,Astronomy and Astrophysics ,Astrophysics ,Stars ,Noise ,Pulsar ,Space and Planetary Science ,Bounding overwatch ,Modulation (music) ,Astrophysics::Solar and Stellar Astrophysics ,Glitch (astronomy) ,Second derivative - Abstract
The braking index is an important factor when examining the pulsar braking mechanism. Measuring braking indices requires measuring the pulsar period and its first and second derivatives. Among them, the second derivative is easily contaminated by timing noise and an unresolved glitch effect. The absence of data bounding a given transition into (or out of) a radio-on phase is another disadvantage in measuring the second derivatives of intermittent pulsars, as was recently demonstrated by Young and coworkers. But, the observed period first derivatives, in the "on" and "off" states of the intermittent pulsars, give us a possible way to predict their braking indices even though they are hard to observe. In this paper, we will give a simple and useful method to study the braking indices of intermittent pulsars. As an application of our method, we will calculate the possible braking indices of three intermittent pulsars and one nulling pulsar, namely, PSR B1931 + 24, PSR J1841 0500, PSR J1832 + 0029 and PSR B0823 + 26, under three different magnetospheric conditions, which include polar cap size variation, charge density variation and the combination of the above two cases. We have found that all the braking indices we predicted are almost within the observed domain It is concluded that, in a relatively short observation period, in which the variation of the braking index can be ignored, we can accurately predict the braking indices of intermittent pulsars, under a specific magnetosphere model, by using the observed "on" and "off" state period first derivatives.
- Published
- 2014
189. An Optical and X-Ray Study of the Contact Binary, BH Cassiopeiae
- Author
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Zixi Li, Jinzhong Liu, Junhui Liu, Ali Esamdin, Chun-Hai Bai, Chin-Ping Hu, Tingting Chen, Hubiao Niu, Juanjuan Ren, Ge Liang, Jie Zheng, Jun-Bo Zhang, and Yu Zhang
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Angular momentum ,010504 meteorology & atmospheric sciences ,Bremsstrahlung ,FOS: Physical sciences ,Astronomy and Astrophysics ,Contact binary ,Astrophysics ,Light curve ,Stellar classification ,01 natural sciences ,Spectral line ,law.invention ,Luminosity ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,law ,0103 physical sciences ,Astrophysics - High Energy Astrophysical Phenomena ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Flare - Abstract
We present the revised and high quality CCD time series observations in 2017 and 2018 of the W UMa-type contact binary BH~Cas. The combination of our new determinations of minimum times and those collected from the literatures reveal a long-term period increase with a rate of $\textit{dP/dt}\,=\,+3.27 \times 10^{-7} \textrm{d}\,\textrm{yr}^{-1}$, which can be accounted for by angular momentum transfer as the less-massive component loses its mass to the more massive one. One cyclical oscillation ($A'=0.00300$~days and $P'=20.09$~yrs) superimposed on the long-term period increase tendency is attributed to one additional object that orbits BH Cas. The low-resolution spectra of this source are observed at phase $\sim$0.0 and $\sim$0.5 in 2018 and 2019, and the spectral types are identified as K3V$\,\pm\,$1 and G8V$\,\pm\,$2. According to the luminosity contributions and spectra at these phases, the spectral type of the primary star is close to K3V$\,\pm\,$1. We infer a cool spot on the hotter and less-massive component to fit the asymmetry of light curves. In addition, changes in the location, temperature, and area of spots on the secondary star in different observations may indicate that the magnetic field activity of the secondary is more active than that of the primary. Such strong spot activities and optical flare are both detected at the same time from a W UMa-type star for the first time. With the \emph{XMM-Newton} observations taken in 2003 and 2012, the X-ray light curve is obtained and the X-ray spectra can be well described with a black-body or a bremsstrahlung model. The soft X-ray luminosity of BH Cas is estimated as 8.8\,--\,9.7$\,\times\,10^{30}$\,erg\,s$^{-1}$., 22 pages, 9 figures, Accepted for publication in the PASP
- Published
- 2019
190. Qatar Exoplanet Survey: Qatar-8b, 9b, and 10b—A Hot Saturn and Two Hot Jupiters
- Author
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A. Daassou, David W. Latham, S. Pyrzas, Nobuhiko Kusakabe, Zouhair Benkhaldoun, Pilar Montañés-Rodríguez, Akihiko Fukui, Khalid Barkaoui, Felipe Murgas, Michaël Gillon, Allyson Bieryla, Luigi Mancini, Zlatan Tsvetanov, M. Bretton, N. Vilchez, Lu Ma, Motohide Tamura, Dimitris Mislis, Norio Narita, Emmanuel Jehin, Gilbert A. Esquerdo, Hannu Parviainien, Ali Esamdin, Enric Palle, Jinzhong Liu, John Southworth, Khalid Al-Subai, Francisco J. Pozuelos, and Jason D. Eastman
- Subjects
Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,planets and satellites: detection ,Saturn (rocket family) ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,Planetary system ,Exoplanet ,techniques: photometric ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Settore FIS/05 - Astronomia e Astrofisica ,Space and Planetary Science ,Planet ,planetary systems ,planets and satellites: fundamental parameters ,Hot Jupiter ,Solar and Stellar Astrophysics (astro-ph.SR) ,Main sequence ,Astrophysics - Earth and Planetary Astrophysics ,QB ,QB799 - Abstract
In this paper we present three new extrasolar planets from the Qatar Exoplanet Survey (QES). Qatar-8b is a hot Saturn, with Mpl = 0.37 Mjup and Rpl = 1.3 Rjup, orbiting a solar-like star every Porb = 3.7 days. Qatar-9b is a hot Jupiter with a mass of Mpl = 1.2 Mjup and a radius of Rpl = 1 Rjup, in a Porb = 1.5 days orbit around a low mass, Mstar = 0.7 Msun, mid-K main-sequence star. Finally, Qatar-10b is a hot, Teq ~ 2000 K, sub-Jupiter mass planet, Mpl = 0.7 Mjup, with a radius of Rpl = 1.54 Rjup and an orbital period of Porb = 1.6 days, placing it on the edge of the sub-Jupiter desert., Comment: arXiv admin note: text overlap with arXiv:1812.05601, arXiv:1712.03216
- Published
- 2019
191. Pulsations of the SX Phe Star BL Camelopardalis
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Taozhi Yang, Peng Zong, Jinzhong Liu, Ali Esamdin, Yu Zhang, Jian-Ning Fu, Hubiao Niu, Guo Jie Feng, and Chun Hai Bai
- Subjects
Physics ,010504 meteorology & atmospheric sciences ,Triple system ,Star (game theory) ,Diagram ,Brown dwarf ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Light curve ,01 natural sciences ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,0103 physical sciences ,Curve fitting ,Binary system ,Maxima ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences - Abstract
We carried out photometric observations of the SX Phe star BL Cam in 2014, 2017 and 2018 using Nanshan 1-m telescope. In addition to the dominated frequency of 25.5790(3) cd$^{-1}$ and its two harmonics, an independent frequency of 25.247 (2) cd$^{-1}$, which is a nonradial mode frequency, was detected from the data in 2014. A total of 123 new times of light maxima were determined from our light curves in the three years, which, together with that published in the literature, were used to analyze the $O$$-$$C$ diagram. The change rate of the main period was derived as (1/P)(dP/dt) = -2.39 (8)$\times$10$^{-8}$ yr$^{-1}$, which is lower than that published in previous literature. A periodical change with a period of 14.01 (9) yr was found in the residuals of the $O$$-$$C$ curve fitting. If it was caused by the light-time effect, BL Cam should be a binary system. The mass of the companion was restricted as low as that of a brown dwarf. No evidence of the triple system suggested by previous authors was shown in our analysis.
- Published
- 2019
192. A fast inversion method of parameters for contact binaries based on differential evolution
- Author
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Zeng, X., Song, J., Zheng, S., Xu, G., Zeng, S., Wang, Y., Esamdin, A., Huang, Y., Xia, S., and Huang, J.
- Abstract
With the development of modern astronomical observation techniques and contact binary research, a large number of light curves of contact binaries have been published, and it has become a challenge to quickly derive the basic physical parameters of contact binaries from their light curves. This article presents a neural network (NN) based on the differential evolution intelligent optimization algorithm to infer the fundamental physical parameters of contact binaries from their light curve. Based on a large dataset of light curves and parameter data generated by Phoebe, a NN mapping model is established, while Differential Evolution (DE) and Markov Chain Monte Carlo (MCMC) algorithms are used to find reasonable parameter combinations, respectively. The experiments show that the parameter inversion speed of the DE algorithm is approximately 50% faster than that of the MCMC algorithm, while guaranteeing a parameter accuracy at least consistent with the those of MCMC algorithm.
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- 2024
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193. Second Braking Index of Intermittent Pulsar and Nulling Pulsar.
- Author
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Rusul, Abdujappar, Zheng, Xiao-Ping, Esamdin, Ali, and Guo, Liang
- Abstract
The braking index parameter of intermittent pulsar would provide important insight into the pulsar slowdown and emission mechanism. In previous work, we presented the first braking index of the intermittent pulsar B1931+24, J1841−0500, J1832+0029 and nulling pulsar B0823+26, by using their observed spin frequency first derivatives in "on" and "off" states. In this paper, to improve and justify our method for studying the braking mechanism of intermittent pulsars, we continue to formulate a method in which the second braking indices, , of these pulsars can also be given with only the observed spin frequency first derivatives and. This paper will discuss, according to the emission and spin-down property of intermittent pulsars, three different magnetospheric configuration changes in the polar cap region. We find our approach produces feasible values of the second braking index of intermittent pulsar. Our calculations of the second braking indices are in close agreement with predicted second braking indices m = n(2n − 1), which are given by simple spin-down law of pulsar spin evolution, resulting in indirect observational support to our model. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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194. A Weak Modulation Effect Detected in the Light Curves of KIC 5950759: Intrinsic or Instrumental Effect?
- Author
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Yang, Taozhi, primary, Esamdin, A., additional, Song, Fangfang, additional, Niu, Hubiao, additional, Feng, Guojie, additional, Zong, Peng, additional, Zeng, Xiangyun, additional, Liu, Junhui, additional, Liu, Jinzhong, additional, Ma, Lu, additional, and Zhao, Fei, additional
- Published
- 2018
- Full Text
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195. UPGRADED 1 METER TELESCOPE AND SCIENCE PROJECTS
- Author
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Ehgamberdiev, Shuhrat A., primary, Hojaev, Alisher S., additional, Burkhanov, O., additional, Yuldoshev, Q., additional, Karimov, R., additional, Mirzakulov, D., additional, Zhao, Gang, additional, Fan, Zhou, additional, Jiang, Xiaojun, additional, Wang, Wei, additional, Chen, Yu-Qin, additional, Liu, Yu-Juan, additional, Zhao, Jing-Kun, additional, Zheng, Jie, additional, Tan, Ke-Feng, additional, He, Wei, additional, Li, Hai-Ning, additional, Song, Yi-Han, additional, Wang, JiangFeng, additional, Zhang, Xiao-Ming, additional, Ge, Liang, additional, Zeng, Xian-Qun, additional, Hou, Zhi-Gang, additional, Wang, JinHu, additional, Ma, Lu, additional, Esamdin, Ali, additional, Liu, Jinzhong, additional, Green, Richard, additional, Wang, Guo-Min, additional, Xu, Jin, additional, and Chen, Liang, additional
- Published
- 2018
- Full Text
- View/download PDF
196. Qatar Exoplanet Survey: Qatar-6b—A Grazing Transiting Hot Jupiter
- Author
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Alsubai, Khalid, primary, Tsvetanov, Zlatan I., additional, Latham, David W., additional, Bieryla, Allyson, additional, Esquerdo, Gilbert A., additional, Mislis, Dimitris, additional, Pyrzas, Stylianos, additional, Foxell, Emma, additional, McCormac, James, additional, Baranec, Christoph, additional, Vilchez, Nicolas P. E., additional, West, Richard, additional, Esamdin, Ali, additional, Dang, Zhenwei, additional, Dalee, Hani M., additional, Al-Rajihi, Amani A., additional, and Al-Harbi, Abeer Kh., additional
- Published
- 2018
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197. Pulsations of the High-AmplitudeδScuti star YZ Bootis
- Author
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Yang, Tao-Zhi, primary, Esamdin, Ali, additional, Fu, Jian-Ning, additional, Niu, Hu-Biao, additional, Feng, Guo-Jie, additional, Song, Fang-Fang, additional, Liu, Jin-Zhong, additional, and Ma, Lu, additional
- Published
- 2018
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198. Short timescale intensity fluctuations of PSR B1133+16 and PSR B1237+25 due to interstellar scintillation at 1.54 GHz
- Author
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Na Wang, Hubiao Niu, and Ali Esamdin
- Subjects
Physics ,Scintillation ,Space and Planetary Science ,Kolmogorov spectrum ,Astrophysics::High Energy Astrophysical Phenomena ,Structure function ,Autocorrelation ,Astronomy and Astrophysics ,Astrophysics ,Expected value ,Pulse intensity ,Cosmology ,Intensity (physics) - Abstract
We report on the short timescale intensity fluctuations of PSR B1133+16 and PSR B1237+25 due to scintillation at 1.54 GHz. The structure functions of intensity fluctuations are constructed and the linear fittings are applied to the structure regime in log–log plots to get the slope values. The slope of the SFs for PSR B1237+25 are less than that of PSR B1133+16, and both of them are much less than 2. For PSR B1133+16, the slope values agree very well with a Kolmogorov spectrum predicted value 5/3, whereas PSR B1237+25 not. We investigate the dynamic spectrum and obtain its auto-correlation function (ACF). Scintillation parameters are obtained by fitting to the autocorrelation function of the dynamic spectrum. The observed diffractive interstellar scintillation (DISS) timescales agree well with the observations and are consistent with some expected values, but the observed de-correlation frequency bandwidths are much less than predicted ones. The expected refractive interstellar scintillation (RISS) timescales are also estimated by using our derived diffractive scintillation parameters. They are consistent with the timescales of slow pulse intensity fluctuations. We proposed that the short timescale of pulse intensity variations caused by the DISS are modulated by the slow variations due to the effects of RISS.
- Published
- 2013
199. Qatar Exoplanet Survey: Qatar-6b -- a grazing transiting hot Jupiter
- Author
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Alsubai, Khalid, Tsvetanov, Zlatan I., Latham, David W., Bieryla, Allyson, Esquerdo, Gilbert A., Mislis, Dimitris, Pyrzas, Stylianos, Foxell, Emma, McCormac, James, Baranec, Christoph, Vilchez, Nicolas P. E., West, Richard, Esamdin, Ali, Dang, Zhenwei, Dalee, Hani M., Al-Rajihi, Amani A., Al-Harbi, Abeer Kh., Alsubai, Khalid, Tsvetanov, Zlatan I., Latham, David W., Bieryla, Allyson, Esquerdo, Gilbert A., Mislis, Dimitris, Pyrzas, Stylianos, Foxell, Emma, McCormac, James, Baranec, Christoph, Vilchez, Nicolas P. E., West, Richard, Esamdin, Ali, Dang, Zhenwei, Dalee, Hani M., Al-Rajihi, Amani A., and Al-Harbi, Abeer Kh.
- Abstract
We report the discovery of Qatar-6b, a new transiting planet identified by the Qatar Exoplanet Survey (QES). The planet orbits a relatively bright (V=11.44), early-K main-sequence star at an orbital period of P~3.506 days. An SED fit to available multi-band photometry, ranging from the near-UV to the mid-IR, yields a distance of d = 101 +/- 6 pc to the system. From a global fit to follow-up photometric and spectroscopic observations, we calculate the mass and radius of the planet to be Mp = 0.67 +/- 0.07 Mjup and Rp = 1.06 +/- 0.07 Rjup, respectively. We use multi-color photometric light curves to show that the transit is grazing, making Qatar-6b one of the few exoplanets known in a grazing transit configuration. It adds to the short list of targets that offer the best opportunity to look for additional bodies in the host planetary system through variations in the transit impact factor and duration.
- Published
- 2017
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200. A study of the strong pulses detected from PSR B0656+14 using the Urumqi 25-m radio telescope at 1540 MHz
- Author
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Huidong Hu, Jing Li, Maofei Qian, Guo-Cun Tao, Ali Esamdin, and Na Wang
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,FOS: Physical sciences ,Flux ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Pulse (physics) ,Radio telescope ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Log-normal distribution ,Astrophysics - High Energy Astrophysical Phenomena ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
We report on the properties of strong pulses from PSR B0656+14 by analyzing the data obtained using Urumqi 25-m radio telescope at 1540 MHz from August 2007 to September 2010. In 44 hrs of observational data, a total of 67 pulses with signal-to-noise ratios above a 5-{\sigma} threshold were detected. The peak flux densities of these pulses are 58 to 194 times that of the average profile, and the pulse energies of them are 3 to 68 times that of the average pulse. These pulses are clustered around phases about 5 degrees ahead of the peak of the average profile. Comparing with the width of the average profile, they are relatively narrow, with the full widths at half-maximum range from 0.28 to 1.78 degrees. The distribution of pulse-energies of the pulses follows a lognormal distribution. These sporadic strong pulses detected from PSR B0656+14 are different in character from the typical giant pulses, and from its regular pulses., Comment: 6 pages, 3 figures, Accepted by RAA
- Published
- 2012
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