Discovery of unusual pulsations in the cool, evolved Am stars HD 98851 and HD 102480
文献类型：期刊论文
| 作者 | Joshi, S; Girish, V; Sagar, R; Kurtz, DW; Martinez, P; Kumar, B; Seetha, S; Ashoka, BN; Zhou, A |
| 刊名 | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
 |
| 出版日期 | 2003-09-11 |
| 卷号 | 344期号:2页码:431-438 |
| 关键词 | stars : chemically peculiar stars : individual : HD 98851 stars : individual : HD 10248 delta Scuti |
| 英文摘要 | The chemically peculiar (CP) stars HD 98851 and HD 102480 have been discovered to be unusual pulsators during the 'Naini Tal-Cape Survey' programme to search for pulsational variability in CP stars. Time series photometric and spectroscopic observations of these newly discovered stars are reported here. Fourier analyses of the time series photometry reveal that HD 98851 is pulsating mainly with frequencies 0.208 and 0.103 mHz, and HD 102480 is pulsating with frequencies 0.107, 0.156 and 0.198 mHz. The frequency identifications are all subject to 1 d(-1) cycle count ambiguities. We have matched the observed low-resolution spectra of HD 98851 and HD 102480 in the range 3500-7400 Angstrom with theoretical synthetic spectra using Kurucz models with solar metallicity and a micro-turbulent velocity of 2 km s(-1). These yield T-eff=7000+/-250 K, log g=3.5+/-0.5 for HD 98851 and T-eff=6750+/-250 K, log g=3.0+/-0.5 for HD 102480. We determined the equivalent H-line spectral class of these stars to be F1 IV and F3 III/IV, respectively. A comparison of the location of HD 98851 and HD 102480 in the HR diagram with theoretical stellar evolutionary tracks indicates that both stars are about 1-Gyr-old, 2-M-circle dot stars that lie towards the red edge of the delta Sct instability strip. From comparison between the observed and calculated physical parameters, we conclude that HD 98851 and HD 102480 are cool, evolved Am pulsators. The light curves of these pulsating stars have alternating high and low amplitudes, nearly harmonic (or subharmonic) period ratios, high pulsational overtones and Am spectral types. This is unusual for both Am and delta Sct pulsators, making these stars interesting objects for further observational and theoretical studies. |
| 收录类别 | SCI |
| 语种 | 英语 |
| WOS记录号 | WOS:000185190900012 |
| 源URL | [http://ir.bao.ac.cn/handle/114a11/8471]  |
| 专题 | 国家天文台_光学天文研究部 |
| 作者单位 | 1.Uttar Pradesh State Observ, Naini Tal 263129, India 2.ISRO Satellite Ctr, Bangalore 560034, Karnataka, India 3.Univ Cent Lancashire, Ctr Astrophys, Preston PR1 2HE, Lancs, England 4.S African Astron Observ, ZA-7935 Cape Town, South Africa 5.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China |
| 推荐引用方式 GB/T 7714 | Joshi, S,Girish, V,Sagar, R,et al. Discovery of unusual pulsations in the cool, evolved Am stars HD 98851 and HD 102480[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2003,344(2):431-438. |
| APA | Joshi, S.,Girish, V.,Sagar, R.,Kurtz, DW.,Martinez, P.,...&Zhou, A.(2003).Discovery of unusual pulsations in the cool, evolved Am stars HD 98851 and HD 102480.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,344(2),431-438. |
| MLA | Joshi, S,et al."Discovery of unusual pulsations in the cool, evolved Am stars HD 98851 and HD 102480".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 344.2(2003):431-438. |
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来源：国家天文台
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