排序方式： 共有40条查询结果，搜索用时 22 毫秒
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M. Hernandez W. P. S. Meikle A. Aparicio C. R. Benn M. R. Burleigh A. C. Chrysostomou A. J. L. Fernandes T. R. Geballe P. L. Hammersley J. Iglesias-Paramo D. J. James P. A. James S. N. Kemp T. A. Lister D. Martinez-Delgado A. Oscoz D. L. Pollacco M. Rozas S. J. Smartt P. Sorensen R. A. Swaters J. H. Telting W. D. Vacca N. A. Walton M. R. Zapatero-Osorio 《Monthly notices of the Royal Astronomical Society》2000,319(1):223-234
We present first-season infrared (IR) and optical photometry and spectroscopy of the Type Ia Supernova 1998bu in M96. We also report optical polarimetry of this event. SN 1998bu is one of the closest type Ia supernovae of modern times, and the distance of its host galaxy is well determined. We find that SN 1998bu is both photometrically and spectroscopically normal. However, the extinction to this event is unusually high, with We find that SN 1998bu peaked at an intrinsic Adopting a distance modulus of 30.25 (Tanvir et al.) and using Phillips et al.'s relations for the Hubble constant, we obtain Combination of our IR photometry with those of Jha et al. provides one of the most complete early-phase IR light curves for a SN Ia published so far. In particular, SN 1998bu is the first normal SN Ia for which good pre- t B max IR coverage has been obtained. It reveals that the J , H and K light curves peak about 5 days earlier than the flux in the B -band curve. 相似文献
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M. A. Hendry S. J. Smartt J. R. Maund A. Pastorello L. Zampieri S. Benetti M. Turatto E. Cappellaro W. P. S. Meikle R. Kotak M. J. Irwin P. G. Jonker L. Vermaas R. F. Peletier H. van Woerden K. M. Exter D. L. Pollacco S. Leon S. Verley C. R. Benn G. Pignata 《Monthly notices of the Royal Astronomical Society》2005,359(3):906-926
We present photometric and spectroscopic data of the Type II-P supernova (SN II-P) 2003gd, which was discovered in M74 close to the end of its plateau phase. SN 2003gd is the first Type II supernova (SN) to have a directly confirmed red supergiant (RSG) progenitor. We compare SN 2003gd to SN 1999em, a similar SN II-P, and estimate an explosion date of 2003 March 18. We determine a reddening towards the SN of E ( B − V ) = 0.14 ± 0.06 , using three different methods. We also calculate three new distances to M74 of 9.6 ± 2.8, 7.7 ± 1.7 and 9.6 ± 2.2 Mpc . The former was estimated using the standard candle method (SCM), for Type II supernovae (SNe II), and the latter two using the brightest supergiants method (BSM). When combined with existing kinematic and BSM distance estimates, we derive a mean value of 9.3 ± 1.8 Mpc . SN 2003gd was found to have a lower tail luminosity compared with other normal Type II-P supernovae (SNe II-P) bringing into question the nature of this SN. We present a discussion concluding that this is a normal SN II-P, which is consistent with the observed progenitor mass of 8+4 −2 M⊙ . 相似文献
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Charles W. Querfeld Raymond N. Smartt Veronique Bommier Egidio Landi Degl'innocenti Lewis L. House 《Solar physics》1985,96(2):277-292
The Stokes components of He i D3 emission in two quiescent prominences, using full spectral profile measurements, are analyzed to derive vector magnetic fields. Two independently developed schemes, based on the Hanle effect, are used for interpretation. They involve solutions of the statistical equilibrium equations for the He i D3 multiplet, including the effect of coherency and full level crossing, which predict the magnetic field dependence of the observed polarization. Derived magnetic field vector solutions for each pair of linear polarization Stokes profiles corresponding to an observational point in the prominence are, intrinsically, not uniquely determined, and a set of possible solutions is usually obtained. However, mutual consistency of these solutions with those independently predicted by the form of the circular polarized component, allow, in almost all cases, rejection of all solutions of a set except one symmetrical pair. Of such a pair, a unique solution can be determined with a high confidence level by reference to independent potential field information. Field vectors are found usually to be close to horizontal and normal to the prominence surface, but extreme exceptions are found. Field values range from 6 G to 60 G. The derived vectorfield configurations and their magnitudes are briefly discussed relative to these prominences and to different quiescent prominence models.The National Center for Atmospheric Research is sponsored by the National Science Foundation.Operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation. 相似文献
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M. J. Darnley † M. F. Bode E. Kerins A. M. Newsam J. An P. Baillon V. Belokurov S. Calchi Novati B. J. Carr M. Crézé N. W. Evans Y. Giraud-Héraud A. Gould P. Hewett Ph. Jetzer J. Kaplan S. Paulin-Henriksson S. J. Smartt Y. Tsapras M. Weston 《Monthly notices of the Royal Astronomical Society》2006,369(1):257-271
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Lokesh Bharti Thomas Rimmele Rajmal Jain S. N. A. Jaaffrey R. N. Smartt 《Monthly notices of the Royal Astronomical Society》2007,376(3):1291-1295
A multiwavelength photometric analysis was performed in order to study the sub-structure of a sunspot light bridge in the photosphere and the chromosphere. Active region NOAA 8350 was observed on 1998 October 8. The data consist of a 100 min time series of 2D spectral scans of the lines Fe i 5576 Å, Hα 6563 Å, Fe i 6302.5 Å, and continuum images at 5571 Å. We recorded line-of-sight magnetograms in 6302.5 Å. The observations were taken at the Dunn Solar Telescope at US National Solar Observatory, Sacramento Peak. We find evidence for plasma ejection from a light bridge followed by Ellerman bombs. Magnetograms of the same region reveal opposite polarity in light bridge with respect to the umbra. These facts support the notion that low-altitude magnetic reconnection can result in the magnetic cancellation as observed in the photosphere. 相似文献
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R. Grant Athay Charles W. Querfeld Raymond N. Smartt Egidio Landi Degl'innocenti Veronique Bommier 《Solar physics》1983,89(1):3-30
Observations of linear polarization in two resolved components of HeI D3 are interpreted using the Hanle effect to determine vector magnetic fields in thirteen prominences. As in all vector magnetic field measurements, there is a two-fold ambiguity in field direction that is symmetric to a 180° rotation about the line-of-sight. The polar angles of the fields show a pronounced preference to be close to 90° from the local solar radius, i.e., the field direction is close to horizontal. Azimuth angles show internal consistency from point to point in a given prominences, but because of the rotational symmetry, the fields may be interpreted, in most cases, as crossing the prominence either in the same sense as the underlying photospheric fields or in the opposite sense. An exceptionally well observed large prominence of approximately planar geometry exhibits no measurable change in the vector magnetic field either with height or with location along the prominence axis. A second well observed large prominence overlying a sharply curved magnetic neutral line, when interpreted assuming that the prominence field has the same sense as the photospheric field, shows a rotation in the azimuth angle of the field relative to the observer by about 150° and relative to the local plane of the prominence by about 65°. In the alternative interpretation in which the prominence field has the opposite sense of the photospheric field, the field still rotates by 150° relative to the observer but remains essentially constant with respect to the plane of the prominence. This prominence erupted shortly after the extended observations. One good quality observation during the course of the eruption gives a vector field fully consistent with the pre-eruption field in the same segment of the prominence. 相似文献
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S. Mattila W. P. S. Meikle P. Lundqvist A. Pastorello R. Kotak J. Eldridge S. Smartt A. Adamson C. L. Gerardy L. Rizzi A. W. Stephens S. D. Van Dyk 《Monthly notices of the Royal Astronomical Society》2008,389(1):141-155
We present near- (NIR) and mid-infrared (MIR) photometric data of the Type Ibn supernova (SN) 2006jc obtained with the United Kingdom Infrared Telescope (UKIRT), the Gemini North Telescope and the Spitzer Space Telescope between days 86 and 493 post-explosion. We find that the IR behaviour of SN 2006jc can be explained as a combination of IR echoes from two manifestations of circumstellar material. The bulk of the NIR emission arises from an IR echo from newly condensed dust in a cool dense shell (CDS) produced by the interaction of the ejecta outward shock with a dense shell of circumstellar material ejected by the progenitor in a luminous blue variable (LBV)-like outburst about two years prior to the SN explosion. The CDS dust mass reaches a modest 3.0 × 10−4 M⊙ by day 230. While dust condensation within a CDS formed behind the ejecta inward shock has been proposed before for one event (SN 1998S), SN 2006jc is the first one showing evidence for dust condensation in a CDS formed behind the ejecta outward shock in the circumstellar material. At later epochs, a substantial and growing contribution to the IR fluxes arises from an IR echo from pre-existing dust in the progenitor wind. The mass of the pre-existing circumstellar medium (CSM) dust is at least ∼8 × 10−3 M⊙ . This paper therefore adds to the evidence that mass-loss from the progenitors of core-collapse SNe could be a major source of dust in the Universe. However, yet again, we see no direct evidence that the explosion of an SN produces anything other than a very modest amount of dust. 相似文献