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V. J. Mclntyre A. C. Gilmore J. B. Hearnshaw 《Journal of Astrophysics and Astronomy》1990,11(1):81-123
Photographic spectra of SN1987A in the LMC have been obtained from 1987 February 25 to 1988 June 30. Microdensitometer tracings
of these have been reduced to intensity and corrections for instrumental response have been applied to the spectra. This paper
presents these data in an atlas format, discusses the reduction procedures in detail, and presents radial velocity measurements
of selected lines in the spectra 相似文献
3.
Zhang Qing Wang Li-fan Hu Jing-yao P. A. Mazzali Wang Zhen-ru 《Chinese Astronomy and Astrophysics》1995,19(4):426-431
We present the modeling of the ultraviolet and optical spectra obtained simultaneously on 1993 April 15 with the HST and at Lick Observatory. A Monte Carlo code is employed in the modeling and a comparison is made between models reported by different groups. With an atmosphere similar to the Sun in chemical composition, the observed spectral lines are well reproduced by a power law density structure of index around 20 except the strong H and HeI λ5876 lines which have peculiar absorption profiles. The photospheric velocity is found to be 9500 km/s and the blackbody temperature of the spectrum is 7990 K. For H and HeI λ5876, we suggest a two-component density structure which has a smoother layer located immediately outside the steeply decreasing inner envelope. The power law indices are most probably 20 and 3, respectively, with the transition point at about 13 000 km/s. In addition, this outer smooth layer serves to flatten the far UV spectrum as observed. 相似文献
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东亚南北地震带大震活动性研究 总被引:6,自引:0,他引:6
根据中国南北地震带与青藏-印尼“歹”字型构造带在成因上的联系,提出东亚南北地震带的观点,认为该地震带包含蒙古、中国西部、缅甸和印尼苏门答腊地区。研究了该带大地震活动的同步性、主体活动区的有序转移、大地震之间的多次相关迁移与重复等特征,并划分出了该带的5个大震活跃幕:1887-1912年、1913-1937年、1938-1957年、1958-1976年、1977-2005年。苏门答腊2004年12月26日8.7级和2005年3月29日8.5级巨震标志着该地震带最近一次以主体活动区南移到苏门答腊为特征的活跃时段即将结束。尽管未来一、两年内地震带的中部存在发生7级地震的有利时段,但结合强震图像异常指标反映的孕震状况分析,未来7级地震危险区尚不明朗。 相似文献
6.
Li-Xin Li 《Monthly notices of the Royal Astronomical Society》2007,375(1):240-256
Recently, a soft blackbody component was observed in the early X-ray afterglow of GRB 060218, which was interpreted as shock breakout from the thick wind of the progenitor Wolf–Rayet (WR) star of the underlying Type Ic supernova 2006aj. In this paper, we present a simple model for computing the characteristic quantities (including energy, temperature and time duration) for the transient event from the shock breakout in Type Ibc supernovae produced by the core-collapse of WR stars surrounded by dense winds. In contrast to the case of a star without a strong wind, the shock breakout occurs in the wind region rather than inside the star, caused by the large optical depth in the wind. We find that, for the case of a WR star with a dense wind, the total energy of the radiation generated by the supernova shock breakout is larger than that in the case of the same star without a wind by a factor of >10. The temperature can be either hotter or colder, depending on the wind parameters. The time duration is larger caused by the increase in the effective radius of the star due to the presence of a thick wind. Then, we apply the model to GRB 060218/SN 2006aj. We show that, to explain both the temperature and the total energy of the blackbody component observed in GRB 060218 by the shock breakout, the progenitor WR star has to have an unrealistically large core radius (the radius at optical depth of 20), larger than 100 R⊙ . In spite of this disappointing result, our model is expected to have important applications to the observations on Type Ibc supernovae in which the detection of shock breakout will provide important clues to the progenitors of Type Ibc supernovae. 相似文献
7.
G. Pignata F. Patat S. Benetti S. Blinnikov W. Hillebrandt R. Kotak B. Leibundgut P. A. Mazzali P. Meikle Y. Qiu P. Ruiz-Lapuente S. J. Smartt E. Sorokina M. Stritzinger M. Stehle M. Turatto T. Marsh F. Martin-Luis N. McBride J. Mendez L. Morales-Rueda D. Narbutis R. Street 《Monthly notices of the Royal Astronomical Society》2004,355(1):178-190
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A. Pastorello E. Baron D. Branch L. Zampieri M. Turatto M. Ramina S. Benetti E. Cappellaro M. Salvo F. Patat A. Piemonte J. Sollerman B. Leibundgut G. Altavilla 《Monthly notices of the Royal Astronomical Society》2005,360(3):950-962
We present spectroscopic and photometric observations of the peculiar Type II supernova (SN) 1998A. The light curves and spectra closely resemble those of SN 1987A, suggesting that the SN 1998A progenitor exploded when it was a compact blue supergiant. However, the comparison with SN 1987A also highlights some important differences: SN 1998A is more luminous and the spectra show bluer continua and larger expansion velocities at all epochs. These observational properties indicate that the explosion of SN 1998A is more energetic than SN 1987A and more typical of Type II supernovae. Comparing the observational data with simulations, we deduce that the progenitor of SN 1998A was a massive star (∼25 M⊙ ) with a small pre-supernova radius (≲6 × 1012 cm) . The Ba ii lines, unusually strong in SN 1987A and some faint II-P events, are almost normal in the case of SN 1998A, indicating that the temperature plays a key role in determining their strength. 相似文献
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