In this work,we report observations of three comets:38P/Stephan-Oterma,64P/Swift-Gehrels,and C/2017 M4(ATLAS),conducted with the Nanshan one-meter wide-field telescope in 2018 August and November,and 2019January.We ex...In this work,we report observations of three comets:38P/Stephan-Oterma,64P/Swift-Gehrels,and C/2017 M4(ATLAS),conducted with the Nanshan one-meter wide-field telescope in 2018 August and November,and 2019January.We extracted morphological features through image enhancement techniques and calculated the dust activity parameter,Afρ,along with dust mass loss rates and coma color indices using broadband photometric data.Our morphological analysis uncovered a spectrum of dust characteristics among the observed comets,ranging from a significant twisted structure in comet 38P/Stephan-Oterma’s coma to the regular coma envelope surrounding comet 64P/Swift-Gehrels.The Afρvalues varied between 148.8±0.3 cm for 64P/Swift-Gehrels and1118.5±6.2 cm for C/2017 M4(ATLAS)(measured within a reference aperture radius ofρ=6″),indicating a range from moderate to high activity levels.Dust mass loss rates were estimated from 328.1 kg s^(-1)for comet 64P/Swift-Gehrels to 1395.5 kg s^(-1)for comet C/2017 M4(ATLAS).The color indices of comets 38P/Stephan-Oterma and C/2017 M4(ATLAS)closely resemble the average colors of active short-period comets and active longperiod comets,respectively.In contrast,64P/Swift-Gehrels exhibits a significantly bluer hue than typical Jupiter family comets.展开更多
Objective A new technique of transthoracic lung ultrasonography(TLS) has emerged and demonstrated promising results in acute heart failure diagnosis at an early stage. However, the diagnostic value of ultrasound lung ...Objective A new technique of transthoracic lung ultrasonography(TLS) has emerged and demonstrated promising results in acute heart failure diagnosis at an early stage. However, the diagnostic value of ultrasound lung comets(ULCs) for acute heart failure(AHF) performed in busy emergency department(ED) is uncertain. The present meta-analysis aimed to assess the diagnostic efficiency of ULCs in AHF. Methods We conducted a search on online journal databases to collect the data on TLS performed for diagnosing AHF published up to the end of July 2017. The sensitivity, specificity, positive likelihood ratio(PLR), negative likelihood ratio(NLR), and summary receiver operating characteristic(SROC) curve were calculated. The post-test probability of AHF was calculated by using Bayes analysis. Results We enrolled a total of 15 studies involving 3,309 patients. The value of sensitivity, specificity, PLR, NLR, DOR, area under the SROC curve, and Q* index was 85%, 91%, 8.94, 0.14, 67.24, 0.9587, and 0.9026, respectively. We detected significant heterogeneity among included studies, and therefore, all these results were analyzed under the random-effect model. We also explored possible sources of heterogeneity among the studies by using meta-regression analysis. Results suggest that the time interval between patient’s admission to bedside TLS examination was closely related to TLS accuracy. Conclusion This meta-analysis demonstrated that detecting ULCs is a convenient bedside tool and has high accuracy for early AHF diagnosis in ED. TLS could be recommended to be applied for early diagnosis of AHF in ED.展开更多
Pushed by the results of a preceding publication on the possibly Quaternary Jebel Waqf as Suwwan Meteorite Crater, Jordan [5], where an amazing coincidence of Rapid Climate Changes (RCCs) with Rise and Fall of Neolith...Pushed by the results of a preceding publication on the possibly Quaternary Jebel Waqf as Suwwan Meteorite Crater, Jordan [5], where an amazing coincidence of Rapid Climate Changes (RCCs) with Rise and Fall of Neolithic and Bronze Age Cultures became evident for the Near/Middle East, this paper deals with the same subject, however, relating to the complete Holocene period in the same area and, additionally, in Central Europe as well. By application of modern climatic data [6] comprising isotope analysis (δ18O, 14C, 10Be), acid and aerosol events, and greenhouse gases (CO2, CH4) Greenland ice cores as well as other astro-/geophysical and geological parameters, an overwhelming coincidence/relation/interdependence of both natural and cultural evidences becomes obvious throughout the last 15,000 years across the Northern Hemisphere. Apart from solar output and other astrophysical processes, most important climate- and Earth-related parameters are Mega-Volcanism (i.e.Santorini Greece: ~3640 yr cal. B. P.), Impact Events (i.e. during Mesolithic: ~9600 yr cal. B. P), rapid oceanic current change (DO-Events), and Plate Tectonics (possibly Atlantis-Event: ~11,500 yr cal. B.P. = Pleistocene/Holocene boundary). The most essential parameter is a significant temperature change related to more or less restricted latitude realms of the Northern Hemisphere. Thus, glacier advance/retreat controls the mobility of peoples (i.e. Nations' Migration, Teutonic Empires) and the access to ore deposits (Au, Ag, Cu, Sn, Zn, Pb, Fe) located in Alpine Mountain Ranges (i.e. End-Neolithic, Early Bronze Age). Myths like the Gilgamesh Epos and John Apocalypse convincingly reveal realistic contents relating to natural hazards like tsunamis, impact and flooding events. They unmisunderstandably make obvious that Myths may provide valuable contributions, especially to Geosciences. Some of the controlling parameters interrelate with others or present a kind of hierarchy: Mega-Volcanism/impact events à ejecta à wildfires, heat storms à cosmic wint展开更多
In this work, we report the observations of the long-period comet C/2015 O1 performed on2018 January 29–30 and April 13 with the Nanshan 1-meter wide-field telescope operated by Xinjiang Astronomical Observatory. We ...In this work, we report the observations of the long-period comet C/2015 O1 performed on2018 January 29–30 and April 13 with the Nanshan 1-meter wide-field telescope operated by Xinjiang Astronomical Observatory. We obtain the morphological features of C/2015 O1 using an image enhancement method, and calculate the dust-activity parameter Afρ and the coma color based on photometric analysis. An obvious fan-shaped structure was observed at different observation times. We find that the activity of C/2015 O1 gradually decreases as the comet advances toward perihelion and the observed B-V and V-R colors are consistent with those of other comets.展开更多
High resolution, high signal-to-noise ratio spectra of Comet C/1995 O1 (Hale-Bopp) which provided continuous wavelength coverage from 5500 to 8500 and partial coverage from 4000 to 5500 were obtained with ...High resolution, high signal-to-noise ratio spectra of Comet C/1995 O1 (Hale-Bopp) which provided continuous wavelength coverage from 5500 to 8500 and partial coverage from 4000 to 5500 were obtained with Coudé Echelle Spectrograph at Beijing Astronomical Observ atory on March 26, 28 and April 22, 1997. In the spectra we found 751 emission features among which 577 lines from H, O, Na, C 2, C 3, CN, CH, NH 2, H 2O + were identified.展开更多
A space object exploded near the city of Chelyabinsk on February 15, 2013. Meteorite fragments reached the Earth’s surface, and accordingly we may consider this space object to have been a meteorite. However, this ev...A space object exploded near the city of Chelyabinsk on February 15, 2013. Meteorite fragments reached the Earth’s surface, and accordingly we may consider this space object to have been a meteorite. However, this event showed a number of features not corresponding to the destruction of a meteorite. The space object began to disintegrate at an altitude of 70 km when pressure (dynamical loads) on its front surface was ~6.7 × 103 N·m-2. The substance from the object’s surface was not blown off by drops, as at ablation, but was dumped by jets over a distance up to 1 km. The trail of this space object visually reminded us of a jet aircraft’s contrail, made up of water. But there is no enough water at altitudes of 30 - 70 km. It may be assumed that the object itself delivered water to these altitudes. The calculation of gas rise over the trail showed that the temperature in some parts of this trail was about 900 K. Heating of large masses of gas can be explained not only by the release of kinetic energy of the space object, but also by combustion processes of its substance. Thus, it was concluded that the meteorite could have been delivered by a comet.展开更多
The discovery of a giant comet (C/2014 UN271) at a distance of 29 AU in October 2014 and the later discovery in September 2021 of a dramatic brightening episode offers an ideal opportunity for verifying the prediction...The discovery of a giant comet (C/2014 UN271) at a distance of 29 AU in October 2014 and the later discovery in September 2021 of a dramatic brightening episode offers an ideal opportunity for verifying the predictions of a “biological” comet. The eruptions of the comet at a heliocentric distance of 20 AU are plausibly explained as due to high pressure venting of the products of microbial metabolism in radioactively heated subsurface lakes. The standard non-biological model of comets is woefully inadequate to account for eruptions at such large distances from the sun where surface temperatures are as low as 60 K.展开更多
Cometary nuclei, the remnant icy bodies of planet formation, located at the outer edge of the solar system, are relatively poorly studied because of their small sizes and thus faintness. Thus far more than a hundred l...Cometary nuclei, the remnant icy bodies of planet formation, located at the outer edge of the solar system, are relatively poorly studied because of their small sizes and thus faintness. Thus far more than a hundred large members (size about 100 km) of this cometary population in the Kuiper belt have been identified. Smaller bodies (10 km) are much too faint to image directly and their number so far can only be extrapolated on theoretical grounds. The Taiwan-America Occultation Survey (TAOS) will conduct a census of the number of Kuiper belt objects down to a few km size by monitoring chance stellar occultations by these cometary nuclei. We will set up an array of small (50cm), wide-field (f/1 9) telescopes, each equipped with a 2K squared CCD camera, along a 7 km baseline in central Taiwan at an elevation above ～ 3000 m. The robot telescopes will operate in a coincidence mode, so the sequence and timing of any candidate occultation event can be recorded and distinguished against a false detection. The Lawrence Livermore National Laboratory, the National Central University, and the Academia Sinica, will each contribute one telescope system. Researchers from an international variety of institutes are also participating in the project. Our experiment provides the only means to study the cometary population in the small-sized end of the distrbution. A great number of scientific byproducts, notably variable stars, will also derive from the huge TAOS database, some 10, 000 giga-bytes worth of photometrical measuremements per year.展开更多
An observational result from March 12 to April 15 for comet Hale-Bopp is given in this paper. During this period a fan-shaped erupted region with angular extent of about 100 degrees near the nucleus was seen continual...An observational result from March 12 to April 15 for comet Hale-Bopp is given in this paper. During this period a fan-shaped erupted region with angular extent of about 100 degrees near the nucleus was seen continually. In addition, a shell structure with at most 5 layers often appeared. It is found that these layers were equal-spaced with a distance of about 2×10 4 km and were moving outward with a speed of about 35 m/s. It is suggested that this phenomenon was possibly a kind of wave created by charged attogram dust grains erupted from the nucleus, which collided with either the solar wind or material of the coma. The propagation period of the wave was about 6 days but the spin of the Comet Hale-Bopp could be very slow and the period was about 3 yr. This spin movement had the opposite direction as its orbital motion.展开更多
We present simulation results on evolution development of orbital motion of short-period comets with the revolution period not exceeding 6-7 years, namely comets 21P/Giacobini-Zinner, 26P/Grigg- Skjellerup and 7P/Pons...We present simulation results on evolution development of orbital motion of short-period comets with the revolution period not exceeding 6-7 years, namely comets 21P/Giacobini-Zinner, 26P/Grigg- Skjellerup and 7P/Pons-Winnecke. The calculations cover the range from the date of the object＇s discovery to 2100. Variations in the objects＇ orbital elements under the action of gravity disturbances, taking Earth＇s gravitational potential into account when the small body approaches, are analyzed. Corrected dates of peri- helion passages can be used for scheduling observations.展开更多
The equilibrium potential and dust fragmentation criterion of fluffy dust grains in plasma are calculated for comet P/Halley . It is found that the dust grain acquires its largest negative potential and disruptive pro...The equilibrium potential and dust fragmentation criterion of fluffy dust grains in plasma are calculated for comet P/Halley . It is found that the dust grain acquires its largest negative potential and disruptive probability about 50,000km from the comet where the dust mass spectrum measured by the spacecraft took a great change.展开更多
SUISEI is a suite of computational tools that has been developed over the past three decades and successfully applied to comets;including ComChem, a global, multi-fluid gas dynamics simulation with detailed chemical k...SUISEI is a suite of computational tools that has been developed over the past three decades and successfully applied to comets;including ComChem, a global, multi-fluid gas dynamics simulation with detailed chemical kinetics of the cometary coma;ComDust, a model of comet dust evolution and interaction with gas;and ComNuc, a 3-D simulation of gas and heat flow within the comet nucleus porous subsurface layers. The combination of these tools have resulted in an improved knowledge of chemical species in the comet’s coma and their relationship to native molecules in the nucleus ices by analyzing space- and ground-based observations and in situ measurements from spacecraft missions. A review of SUISEI is presented and applications are made to two cases: chemical recycling of HCN in comets and the physical conditions of the near-Sun object, 3200 Phaethon.展开更多
Amajor objective of the Infrared Space Observatory (ISO) is the determination of the sized and albedoes of several objects in the "Kuiper disc".The method by which this will be achieved is described.It is sh...Amajor objective of the Infrared Space Observatory (ISO) is the determination of the sized and albedoes of several objects in the "Kuiper disc".The method by which this will be achieved is described.It is shown that the unknown shapes and surface thermal properties proviede additional complications to the interpretation of ISO data.The requirement for ground-based measurements of the visual light curves of these objects is demonstrated and the implications of the results of the ISO observ Vations is discussed.展开更多
This paper presents a new approach to analyzing the change of cometary brightness.In our considerations,we assume that astronomical silicates(dust agglomerates)and gas are present in the coma.This assumption is a cons...This paper presents a new approach to analyzing the change of cometary brightness.In our considerations,we assume that astronomical silicates(dust agglomerates)and gas are present in the coma.This assumption is a consequence of the analysis of the result observed during the Rosetta mission to comet67 P/Churyumov-Gerasimenko(abbreviated 67 P/Ch-G).The dimensions of these agglomerates can be up to several centimeters.However,the large ones are few compared to particles with dimensions of several micrometers.This paper presents the results of calculations on the change in hypothetical comet brightness as a result of its outburst.The calculations take into account the percentage of carbonaceous particles and silicates rich in magnesium.展开更多
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region of China(grant No.2021D01B112)Tianshan Talent Training Program through the grant 2023TSYCCX0101。
文摘In this work,we report observations of three comets:38P/Stephan-Oterma,64P/Swift-Gehrels,and C/2017 M4(ATLAS),conducted with the Nanshan one-meter wide-field telescope in 2018 August and November,and 2019January.We extracted morphological features through image enhancement techniques and calculated the dust activity parameter,Afρ,along with dust mass loss rates and coma color indices using broadband photometric data.Our morphological analysis uncovered a spectrum of dust characteristics among the observed comets,ranging from a significant twisted structure in comet 38P/Stephan-Oterma’s coma to the regular coma envelope surrounding comet 64P/Swift-Gehrels.The Afρvalues varied between 148.8±0.3 cm for 64P/Swift-Gehrels and1118.5±6.2 cm for C/2017 M4(ATLAS)(measured within a reference aperture radius ofρ=6″),indicating a range from moderate to high activity levels.Dust mass loss rates were estimated from 328.1 kg s^(-1)for comet 64P/Swift-Gehrels to 1395.5 kg s^(-1)for comet C/2017 M4(ATLAS).The color indices of comets 38P/Stephan-Oterma and C/2017 M4(ATLAS)closely resemble the average colors of active short-period comets and active longperiod comets,respectively.In contrast,64P/Swift-Gehrels exhibits a significantly bluer hue than typical Jupiter family comets.
基金supported by the capital characteristic clinic project of China [Z151100004015071]National Natural Science Foundation of China [51573211]ruiyi emergency medical research fund of China [R2017013]
文摘Objective A new technique of transthoracic lung ultrasonography(TLS) has emerged and demonstrated promising results in acute heart failure diagnosis at an early stage. However, the diagnostic value of ultrasound lung comets(ULCs) for acute heart failure(AHF) performed in busy emergency department(ED) is uncertain. The present meta-analysis aimed to assess the diagnostic efficiency of ULCs in AHF. Methods We conducted a search on online journal databases to collect the data on TLS performed for diagnosing AHF published up to the end of July 2017. The sensitivity, specificity, positive likelihood ratio(PLR), negative likelihood ratio(NLR), and summary receiver operating characteristic(SROC) curve were calculated. The post-test probability of AHF was calculated by using Bayes analysis. Results We enrolled a total of 15 studies involving 3,309 patients. The value of sensitivity, specificity, PLR, NLR, DOR, area under the SROC curve, and Q* index was 85%, 91%, 8.94, 0.14, 67.24, 0.9587, and 0.9026, respectively. We detected significant heterogeneity among included studies, and therefore, all these results were analyzed under the random-effect model. We also explored possible sources of heterogeneity among the studies by using meta-regression analysis. Results suggest that the time interval between patient’s admission to bedside TLS examination was closely related to TLS accuracy. Conclusion This meta-analysis demonstrated that detecting ULCs is a convenient bedside tool and has high accuracy for early AHF diagnosis in ED. TLS could be recommended to be applied for early diagnosis of AHF in ED.
文摘Pushed by the results of a preceding publication on the possibly Quaternary Jebel Waqf as Suwwan Meteorite Crater, Jordan [5], where an amazing coincidence of Rapid Climate Changes (RCCs) with Rise and Fall of Neolithic and Bronze Age Cultures became evident for the Near/Middle East, this paper deals with the same subject, however, relating to the complete Holocene period in the same area and, additionally, in Central Europe as well. By application of modern climatic data [6] comprising isotope analysis (δ18O, 14C, 10Be), acid and aerosol events, and greenhouse gases (CO2, CH4) Greenland ice cores as well as other astro-/geophysical and geological parameters, an overwhelming coincidence/relation/interdependence of both natural and cultural evidences becomes obvious throughout the last 15,000 years across the Northern Hemisphere. Apart from solar output and other astrophysical processes, most important climate- and Earth-related parameters are Mega-Volcanism (i.e.Santorini Greece: ~3640 yr cal. B. P.), Impact Events (i.e. during Mesolithic: ~9600 yr cal. B. P), rapid oceanic current change (DO-Events), and Plate Tectonics (possibly Atlantis-Event: ~11,500 yr cal. B.P. = Pleistocene/Holocene boundary). The most essential parameter is a significant temperature change related to more or less restricted latitude realms of the Northern Hemisphere. Thus, glacier advance/retreat controls the mobility of peoples (i.e. Nations' Migration, Teutonic Empires) and the access to ore deposits (Au, Ag, Cu, Sn, Zn, Pb, Fe) located in Alpine Mountain Ranges (i.e. End-Neolithic, Early Bronze Age). Myths like the Gilgamesh Epos and John Apocalypse convincingly reveal realistic contents relating to natural hazards like tsunamis, impact and flooding events. They unmisunderstandably make obvious that Myths may provide valuable contributions, especially to Geosciences. Some of the controlling parameters interrelate with others or present a kind of hierarchy: Mega-Volcanism/impact events à ejecta à wildfires, heat storms à cosmic wint
基金supported by the program of the light in China’s Western Region (LCWR, Grant No. 2015XBQN-A-02)the National Natural Science Foundation of China (Grant No. 11661161016)+2 种基金the 13th Five-year Informatization Plan of Chinese Academy of Sciences (Grant No. XXH13503–03–107)the Youth Innovation Promotion Association CAS (Grant No. 2018080)the Talent Importing Program offered by the government of Xinjiang Uygur Autonomous Region
文摘In this work, we report the observations of the long-period comet C/2015 O1 performed on2018 January 29–30 and April 13 with the Nanshan 1-meter wide-field telescope operated by Xinjiang Astronomical Observatory. We obtain the morphological features of C/2015 O1 using an image enhancement method, and calculate the dust-activity parameter Afρ and the coma color based on photometric analysis. An obvious fan-shaped structure was observed at different observation times. We find that the activity of C/2015 O1 gradually decreases as the comet advances toward perihelion and the observed B-V and V-R colors are consistent with those of other comets.
文摘High resolution, high signal-to-noise ratio spectra of Comet C/1995 O1 (Hale-Bopp) which provided continuous wavelength coverage from 5500 to 8500 and partial coverage from 4000 to 5500 were obtained with Coudé Echelle Spectrograph at Beijing Astronomical Observ atory on March 26, 28 and April 22, 1997. In the spectra we found 751 emission features among which 577 lines from H, O, Na, C 2, C 3, CN, CH, NH 2, H 2O + were identified.
文摘A space object exploded near the city of Chelyabinsk on February 15, 2013. Meteorite fragments reached the Earth’s surface, and accordingly we may consider this space object to have been a meteorite. However, this event showed a number of features not corresponding to the destruction of a meteorite. The space object began to disintegrate at an altitude of 70 km when pressure (dynamical loads) on its front surface was ~6.7 × 103 N·m-2. The substance from the object’s surface was not blown off by drops, as at ablation, but was dumped by jets over a distance up to 1 km. The trail of this space object visually reminded us of a jet aircraft’s contrail, made up of water. But there is no enough water at altitudes of 30 - 70 km. It may be assumed that the object itself delivered water to these altitudes. The calculation of gas rise over the trail showed that the temperature in some parts of this trail was about 900 K. Heating of large masses of gas can be explained not only by the release of kinetic energy of the space object, but also by combustion processes of its substance. Thus, it was concluded that the meteorite could have been delivered by a comet.
文摘The discovery of a giant comet (C/2014 UN271) at a distance of 29 AU in October 2014 and the later discovery in September 2021 of a dramatic brightening episode offers an ideal opportunity for verifying the predictions of a “biological” comet. The eruptions of the comet at a heliocentric distance of 20 AU are plausibly explained as due to high pressure venting of the products of microbial metabolism in radioactively heated subsurface lakes. The standard non-biological model of comets is woefully inadequate to account for eruptions at such large distances from the sun where surface temperatures are as low as 60 K.
文摘Cometary nuclei, the remnant icy bodies of planet formation, located at the outer edge of the solar system, are relatively poorly studied because of their small sizes and thus faintness. Thus far more than a hundred large members (size about 100 km) of this cometary population in the Kuiper belt have been identified. Smaller bodies (10 km) are much too faint to image directly and their number so far can only be extrapolated on theoretical grounds. The Taiwan-America Occultation Survey (TAOS) will conduct a census of the number of Kuiper belt objects down to a few km size by monitoring chance stellar occultations by these cometary nuclei. We will set up an array of small (50cm), wide-field (f/1 9) telescopes, each equipped with a 2K squared CCD camera, along a 7 km baseline in central Taiwan at an elevation above ～ 3000 m. The robot telescopes will operate in a coincidence mode, so the sequence and timing of any candidate occultation event can be recorded and distinguished against a false detection. The Lawrence Livermore National Laboratory, the National Central University, and the Academia Sinica, will each contribute one telescope system. Researchers from an international variety of institutes are also participating in the project. Our experiment provides the only means to study the cometary population in the small-sized end of the distrbution. A great number of scientific byproducts, notably variable stars, will also derive from the huge TAOS database, some 10, 000 giga-bytes worth of photometrical measuremements per year.
文摘An observational result from March 12 to April 15 for comet Hale-Bopp is given in this paper. During this period a fan-shaped erupted region with angular extent of about 100 degrees near the nucleus was seen continually. In addition, a shell structure with at most 5 layers often appeared. It is found that these layers were equal-spaced with a distance of about 2×10 4 km and were moving outward with a speed of about 35 m/s. It is suggested that this phenomenon was possibly a kind of wave created by charged attogram dust grains erupted from the nucleus, which collided with either the solar wind or material of the coma. The propagation period of the wave was about 6 days but the spin of the Comet Hale-Bopp could be very slow and the period was about 3 yr. This spin movement had the opposite direction as its orbital motion.
文摘We present simulation results on evolution development of orbital motion of short-period comets with the revolution period not exceeding 6-7 years, namely comets 21P/Giacobini-Zinner, 26P/Grigg- Skjellerup and 7P/Pons-Winnecke. The calculations cover the range from the date of the object＇s discovery to 2100. Variations in the objects＇ orbital elements under the action of gravity disturbances, taking Earth＇s gravitational potential into account when the small body approaches, are analyzed. Corrected dates of peri- helion passages can be used for scheduling observations.
基金theNationalNaturalScienceFoundationofChina (No .196 5 30 0 1)
文摘The equilibrium potential and dust fragmentation criterion of fluffy dust grains in plasma are calculated for comet P/Halley . It is found that the dust grain acquires its largest negative potential and disruptive probability about 50,000km from the comet where the dust mass spectrum measured by the spacecraft took a great change.
文摘SUISEI is a suite of computational tools that has been developed over the past three decades and successfully applied to comets;including ComChem, a global, multi-fluid gas dynamics simulation with detailed chemical kinetics of the cometary coma;ComDust, a model of comet dust evolution and interaction with gas;and ComNuc, a 3-D simulation of gas and heat flow within the comet nucleus porous subsurface layers. The combination of these tools have resulted in an improved knowledge of chemical species in the comet’s coma and their relationship to native molecules in the nucleus ices by analyzing space- and ground-based observations and in situ measurements from spacecraft missions. A review of SUISEI is presented and applications are made to two cases: chemical recycling of HCN in comets and the physical conditions of the near-Sun object, 3200 Phaethon.
文摘Amajor objective of the Infrared Space Observatory (ISO) is the determination of the sized and albedoes of several objects in the "Kuiper disc".The method by which this will be achieved is described.It is shown that the unknown shapes and surface thermal properties proviede additional complications to the interpretation of ISO data.The requirement for ground-based measurements of the visual light curves of these objects is demonstrated and the implications of the results of the ISO observ Vations is discussed.
基金the support the author received from the Centre for Innovation and Transfer of Natural Sciences and Engineering Knowledge,University of Rzeszow,Poland。
文摘This paper presents a new approach to analyzing the change of cometary brightness.In our considerations,we assume that astronomical silicates(dust agglomerates)and gas are present in the coma.This assumption is a consequence of the analysis of the result observed during the Rosetta mission to comet67 P/Churyumov-Gerasimenko(abbreviated 67 P/Ch-G).The dimensions of these agglomerates can be up to several centimeters.However,the large ones are few compared to particles with dimensions of several micrometers.This paper presents the results of calculations on the change in hypothetical comet brightness as a result of its outburst.The calculations take into account the percentage of carbonaceous particles and silicates rich in magnesium.
