排序方式： 共有21条查询结果，搜索用时 15 毫秒
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J. I. Arias † N. I. Morrell ‡ R. H. Barbá G. L. Bosch § M. Grosso ¶ M. Corcoran 《Monthly notices of the Royal Astronomical Society》2002,333(1):202-210
We present a new optical spectroscopic study of the O-type binary HD 165052 based on high- and intermediate-resolution CCD observations. We re-investigated the spectral classification of the binary components, obtaining spectral types of O6.5 V and O7.5 V for the primary and secondary, respectively, finding that both stars display weak C iii λ 5696 emission in their spectra. We also determined a radial-velocity orbit for HD 165052 with a period of 2.95510±0.00001 d , and semi-amplitudes of 94.8 and 104.7±0.5 km s-1 , resulting in a mass ratio Q =0.9 . From a comparison with previous radial-velocity determinations, we found evidence of apsidal motion in the system. Several signatures of wind–wind collision, such as phase-locked variability of the X-ray flux and the Struve–Sahade effect, are also considered. It was also found that the reddening in the region should be normal, in contrast with previous determinations. 相似文献
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V. Firpo G. Bosch † N. Morrell †‡ 《Monthly notices of the Royal Astronomical Society》2005,356(4):1357-1361
We present results of a search for giant H ii regions in southern galaxies. Using high-resolution spectra, obtained with the Magellan Inamori Kyocera Echelle (MIKE) at the Las Campanas Magellan II telescope, we were able to resolve the emission-line profiles and determine the intrinsic velocity dispersion of the ionized gas. Out of four observed regions, selected from previous CCD narrow-band photometry, we detected three H ii regions showing supersonic velocity dispersion, characteristic of giant H ii regions, and their location in diagnostic diagrams suggests that a powerful starburst is the source of ionization energy. 相似文献
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Beatriz García Carlos Hernández Stella Malaroda Nidia Morrell Hugo Levato 《Astrophysics and Space Science》1988,148(1):163-173
We determined radial velocities for 25 probable members of the open cluster IC 2602. We identified the stars with variable radial velocity. We improved the orbit of HD 93030, and computed a preliminary orbit for another spectroscopic binary. We discussed with such data the average cluster radial velocity and we compare the incidence of short period binaries among the Main-Sequence members of IC 2602 with the incidence for other clusters with different values of the average axial rotation of their members.Cerro Tololo Interamerican Observatory 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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David G. Ainley C.R. Grau Thomas E. Roudybush Stephen H. Morrell J.M. Utts 《Marine pollution bulletin》1981,12(9):314-317
Sublethal doses of petroleum reduced reproduction in a free-living seabird, Cassin's Auklet (Ptychoramphus aleuticus), nesting on Southeast Farallon Island, California. The proportion of birds laying eggs was reduced 9–13 days after ingestion by gelatin capsule of 300, 600 or 1000 mg bunker C fuel oil, or 1000 mg Prudhoe Bay crude oil. In addition, among those auklets that eventually laid eggs, hatching was reduced by doses of 1000 mg of bunker C but was unaffected by other treatments. Chick development after hatching was unaffected by any treatment. The total time of egg formation from onset of rapid yolk formation to laying was 13 days, and it is early in this period that auklets are vulnerable to petroleum. 相似文献
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The difficulties associated with slurry transportation in autogenous (ag) and semi-autogenous (sag) grinding mills have become more apparent in recent years with the increasing trend to build larger diameter mills for grinding high tonnages. This is particularly noticeable when ag/sag mills are run in closed circuit with classifiers such as fine screens/cyclones. 相似文献
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Sergey V. Marchenko Gregor Rauw Eleonora A. Antokhina Igor I. Antokhin Dominique Ballereau Jacques Chauville Michael F. Corcoran Rafael Costero Juan Echevarria Thomas Eversberg Ken G. Gayley Gloria Koenigsberger Anatoly S. Miroshnichenko Anthony F. J. Moffat Nidia I. Morrell Nancy D. Morrison Christopher L. Mulliss Julian M. Pittard Ian R. Stevens Jean-Marie Vreux Jean Zorec 《Monthly notices of the Royal Astronomical Society》2000,317(2):333-342
With the objective of investigating the windwind collision phenomenon and supporting contemporaneous X-ray observations, we have organized a large-scale, coordinated optical monitoring campaign of the massive, highly eccentric O9 III+B1 III binary Iota Orionis. Successfully separating the spectra of the components, we refine the orbital elements and confirm the rapid apsidal motion in the system. We also see strong interaction between the components during periastron passage and detect phase-locked variability in the spectrum of the secondary star. However, we find no unambiguous signs of the bow shock crashing on the surface of the secondary, despite the predictions of hydrodynamic simulations. Combining all available photometric data, we find rapid, phase-locked variations and model them numerically, thus restricting the orbital inclination to 50° i 70°. 相似文献
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N.I. Morrell † R.H. Barbá † V.S. Niemela ‡ M.A. Corti § J.F. Albacete Colombo G. Rauw ¶ M. Corcoran T. Morel J.-F. Bertrand A.F.J. Moffat N. St-Louis 《Monthly notices of the Royal Astronomical Society》2001,326(1):85-94
A new high-quality set of orbital parameters for the O-type spectroscopic binary HD 93205 has been obtained combining échelle and coudé CCD observations. The radial velocity orbits derived from the He ii λ 4686 Å (primary component) and He i λ 4471 Å (secondary component) absorption lines yield semi-amplitudes of 133±2 and 314±2 km s−1 for each binary component, resulting in minimum masses of 31 and 13 M⊙ ( q =0.42) . We also confirm for the binary components the spectral classification of O3 V+ O8 V previously assigned. Assuming for the O8 V component a 'normal' mass of 22–25 M⊙ we would derive for the primary O3 V a mass of 'only' 52–60 M⊙ and an inclination of about 55° for the orbital plane. We have also determined for the first time a period of apsidal motion for this system, namely 185±16 yr using all available radial velocity data sets of HD 93205 (from 1975 to 1999). Phase-locked variations of the X-ray emission of HD 93205 consisting of a rise of the observed X-ray flux near periastron passage are also discussed. 相似文献
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