Amino acids produced from the ultraviolet/extreme-ultraviolet irradiation of naphthalene in a H₂O+NH₃ ice mixture     

Y.-J. Chen  M. Nuevo  T.-S. Yih  W.-H. Ip  H.-S. Fung  C.-Y. Cheng  H.-R. Tsai  C.-Y. R. Wu 《Monthly notices of the Royal Astronomical Society》2008,384(2):605-610

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Rapid,high-resolution detection of environmental change over continental scales from satellite data – the Earth Observation Data Cube     

Adam Lewis  Leo Lymburner  Matthew B. J. Purss  Brendan Brooke  Ben Evans  Alex Ip 《International Journal of Digital Earth》2016,9(1):106-111

The effort and cost required to convert satellite Earth Observation (EO) data into meaningful geophysical variables has prevented the systematic analysis of all available observations. To overcome these problems, we utilise an integrated High Performance Computing and Data environment to rapidly process, restructure and analyse the Australian Landsat data archive. In this approach, the EO data are assigned to a common grid framework that spans the full geospatial and temporal extent of the observations – the EO Data Cube. This approach is pixel-based and incorporates geometric and spectral calibration and quality assurance of each Earth surface reflectance measurement. We demonstrate the utility of the approach with rapid time-series mapping of surface water across the entire Australian continent using 27 years of continuous, 25?m resolution observations. Our preliminary analysis of the Landsat archive shows how the EO Data Cube can effectively liberate high-resolution EO data from their complex sensor-specific data structures and revolutionise our ability to measure environmental change.  相似文献   

The cometary magnetic field and its associated electric currents     

W-H. Ip  D.A. Mendis 《Icarus》1975,26(4):457-461

Two different observations of Comet Kohoutek (1973f) seem to suggest the existence of substantial magnetic fields $\text{(? 100 γ)}$ in its coma and tail. The effects of the currents and hydromagnetic waves associated with these magnetic fields are considered and it is shown that while the currents closing through the inner coma may represent an important source of ionization in that region, the dissipation of hydromagnetic waves may also be a significant, if not dominant, source of heating there.  相似文献   

Spatial distributions and seasonal variations of features related to a venting process at high southern latitudes observed by the MOC camera     

Jeng-Jong Jian  Wing-Huen Ip  Shin-Reu Sheu 《Planetary and Space Science》2009,57(7):797-803

A distinctive terrain named cryptic region which is characterized by regions of low albedo and low temperature has been identified on the Martian south polar cap. In this zone, many fan- and spider-shaped features of km-scale appeared following the sublimation of the CO₂ frost layer. These peculiar features were apparently caused by a wind-blown system of dust-laden jets. During the warming period starting at L_s∼180°, the seasonal ice cap regresses and fans and spiders appear in sequence. These surface features are repeatable events that tend to occupy the same areas from year to year. In this study, we use the Mars Orbiter camera (MOC) narrow-angle images to produce a statistical study of the time distributions of the fans and spiders as functions of L_s and as functions of the topography. The time variations and spatial distributions of these features are further correlated with the CO₂ ice coverage measured by the Mars Orbiter laser altimeter (MOLA) instrument. We have documented that most of the fans are found in the early spring with L_s<230° and the fans and spiders coexist at L_s=250°±20°. It is also found that there is a strong dependence on latitude and altitude with fans and spiders most often observed at high latitude (>83°S) and high altitude (>2500 m). Our statistical result also indicates that the occurrence of fans is highly correlated with the thickness of the CO₂ frost thus providing support for the venting model.  相似文献   

Interplanetary encounters | E.J.O¨pik, 1976. Elsevier,Amsterdam, 155 pp., U.S. $26,95     

W.-H. Ip 《Earth》1977,13(2):200-201

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On three types of fragmentation processes observed in the asteroid belt     

W.-H. Ip 《Icarus》1979,40(3):418-422

From comparison of the mass ratio and velocity dispersion between the asteroid family members, we find that the fragmentation processes in the asteroid belt could be generally classified into three types: (a) surface cratering; (b) spallation; and (c) complete breakup as observed in the laboratory hypervelocity impact experiments. Whether there is ongoing accretion for large bodies like Ceres, as an additional type of collision process, is still an open question to be answered by further study.  相似文献   

Dynamical study of the Hilda asteroids     

W. -H. Ip 《Astrophysics and Space Science》1976,44(2):373-383

Schubart's model of a planar, elliptic restricted three-body problem is used to study the orbital motion of the Hilda asteroids from thePalomar-Leiden Survey. The 3:2 resonant coupling to Jupiter of some of these small asteroids are found to be stable. However, some of the small asteroids with absolute magnitudeg>15 have large amplitude of variation in their orbital elements in one libration period. Since the lifetime scales against catastrophic collision of the Hilda asteroids are estimated to be several times larger than those of the main belt objects, a significant portion of these resonant asteroids could be the original members of the Hilda group. From this point of view, it is suggested that such size-dependence of resonant orbital motions might be the result of the cosmogonic effects ofjet stream accretion.  相似文献   

A study of the global magnetic activity of the star Kepler-17 using light curve inversion with bipartite regularization     

Tao Luo  Yan-Yan Liang  Wing-Huen Ip  Hao-Zhi Huang  Xu-Xin Lin 《天文和天体物理学研究(英文版)》2021,(4):95-114

A new method of light curve inversion with bipartite regularization(LIBR),which is complementary to the previous treatments by Bonomo and Lanza and Estrela and Valio,is used to reconstruct the physical properties of star spots on the solar-type star Kepler-17 by using the full Q1-Q17 data set.The Markov Chain Monte Carlo(MCMC) method was applied to find the best profile of the reconstructed surface.The known value of the rotation inclination of Kepler-17 allows the generation of a star spot model in a sequence of stellar rotation with a period of 12.26 d.Because of the nature of the light curve inversion,the spot model is limited to the equatorial region.We also investigated the starspot lifetimes of Kepler-17 utilizing the MCMC method.Combined with the LIBR inversion results,it was found that the star spots typically last from one to several stellar rotations.From the time evolution of the spot size,a magnetic cycle period of 437 d can be derived.This value is comparatively shorter than the solar cycle which might be a consequence of the younger age(～1.78 Gyr) of Kepler-17.The light curve of Kepler-17 is characterized by the presence of large-amplitude variation caused by star spots but no superflare activity.An interesting possibility is that the magnetic energy stored in the star spot regions could have been constantly dissipated by electrodynamic interaction between the central star and the hot Jupiter,Kepler-17 b,via a lower-level energy release process.  相似文献   

Chinese records on the correlation of heliocentric planetary alignments and earthquake activities     

W.-H. Ip 《Icarus》1976,29(3):435-436

A short account of the correlation of heliocentric planetary alignments and the earthquake activities in Northern China is given. It appears that such arrangement of planetary orbital positions has no effect on the triggering of earthquakes.  相似文献   

The neutral atmospheres of comets     

D. A. Mendis  W. -H. Ip 《Astrophysics and Space Science》1976,39(2):335-385

In this paper we have endeavored to critically evaluate our present understanding of cometary atmospheres. Following a brief introduction of the significance of the study of cometary atmospheres (Section 1), the relevant photometric and spectroscopic observations are summarized in Section 2.The interaction with the solar radiation, with regard to both the excitation of the observed species as well as the dissociation of stable molecules evaporating from the nucleus, is considered in Sections 3 and 4. The gas phase chemistry likely to take place in the dense inner coma is next considered in Section 5.The exospheric and hydrodynamic models of the expanding cometary atmosphere are considered in detail in Section 6, and both their limitations as well as possible improvements are discussed.The observed chemical composition of the neutral atmosphere and the inferred chemical composition of the volatile component of the nucleus, together with possible variations between different classes of comets is next considered in Section 7, and their possible cosmogonic significance is discussed.In conclusion, some of the important directions in which future research should progress, in order to provide more complete and secure knowledge of cometary atmospheres, are stressed (Section 8).Astrophysics and Space Science Review Paper.  相似文献