Pub Date : 2021-10-01DOI: 10.1017/S1743921321001496
P. Peñarroya, R. Paoli
Abstract Missions to asteroids have been the trend in space exploration for the last years. They provide information about the formation and evolution of the Solar System, contribute to direct planetary defense tasks, and could be potentially exploited for resource mining. Be their purpose as it may, the factor that all these mission types have in common is the challenging dynamical environment they have to deal with. The gravitational environment of a certain asteroid is most of the times not accurately known until very late mission phases when the spacecraft has already orbited the body for some time. Shape models help to estimate the gravitational potential with a density distribution assumption (usually constant value) and some optical measurements of the body. These measurements, unlike the ones needed for harmonic coefficient estimation, can be taken from well before arriving at the asteroid’s sphere of influence, which allows to obtain a better approximation of the gravitational dynamics much sooner. The disadvantage they pose is that obtaining acceleration values from these models implies a heavy computational burden on the on-board processing unit, which is very often too time-consuming for the mission profile. In this paper, the technique developed on [1] is used to create a validated Python-based tool that obtains spherical harmonic coefficients from the shape model of an asteroid or comet, given a certain density for the body. This validated software suite, called AstroHarm, is used to analyse the accuracy of the models obtained and the improvements in computational efficiency in a simulated spacecraft orbiting a small body. The results obtained are shown offering a qualitative comparison between different order spherical harmonic models and the original shape model. Finally, the creation of a catalogue for harmonics is proposed together with some thoughts on complex modelling using this tool.
{"title":"Orbit propagation around small bodies using spherical harmonic coefficients obtained from polyhedron shape models","authors":"P. Peñarroya, R. Paoli","doi":"10.1017/S1743921321001496","DOIUrl":"https://doi.org/10.1017/S1743921321001496","url":null,"abstract":"Abstract Missions to asteroids have been the trend in space exploration for the last years. They provide information about the formation and evolution of the Solar System, contribute to direct planetary defense tasks, and could be potentially exploited for resource mining. Be their purpose as it may, the factor that all these mission types have in common is the challenging dynamical environment they have to deal with. The gravitational environment of a certain asteroid is most of the times not accurately known until very late mission phases when the spacecraft has already orbited the body for some time. Shape models help to estimate the gravitational potential with a density distribution assumption (usually constant value) and some optical measurements of the body. These measurements, unlike the ones needed for harmonic coefficient estimation, can be taken from well before arriving at the asteroid’s sphere of influence, which allows to obtain a better approximation of the gravitational dynamics much sooner. The disadvantage they pose is that obtaining acceleration values from these models implies a heavy computational burden on the on-board processing unit, which is very often too time-consuming for the mission profile. In this paper, the technique developed on [1] is used to create a validated Python-based tool that obtains spherical harmonic coefficients from the shape model of an asteroid or comet, given a certain density for the body. This validated software suite, called AstroHarm, is used to analyse the accuracy of the models obtained and the improvements in computational efficiency in a simulated spacecraft orbiting a small body. The results obtained are shown offering a qualitative comparison between different order spherical harmonic models and the original shape model. Finally, the creation of a catalogue for harmonics is proposed together with some thoughts on complex modelling using this tool.","PeriodicalId":20590,"journal":{"name":"Proceedings of the International Astronomical Union","volume":"39 1","pages":"203 - 210"},"PeriodicalIF":0.0,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88413895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-01DOI: 10.1017/s1743921322001806
{"title":"IAU volume 15 issue 364 Cover and Back matter","authors":"","doi":"10.1017/s1743921322001806","DOIUrl":"https://doi.org/10.1017/s1743921322001806","url":null,"abstract":"","PeriodicalId":20590,"journal":{"name":"Proceedings of the International Astronomical Union","volume":"34 1","pages":"b1 - b3"},"PeriodicalIF":0.0,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77315738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-01DOI: 10.1017/S1743921322000746
M. Vasileva, E. Kuznetsov, A. Rosaev, E. Plávalová
Abstract We have found three new members of the Rampo asteroids family: 2009HD95, 2010VO19, 2013JF69. We estimated the Yarkovsky semimajor axis drift rate. Based on the simulation results, estimates of the asteroid pairs’ age included in the family are obtained. In the scenario of the cascade disruption of the parent body of the asteroid (10321) Rampo, one can note the concentration of estimates of the pairs’ age to values of 900, 750, 500, and 250 kyr.
{"title":"Cascade disruption in Rampo family","authors":"M. Vasileva, E. Kuznetsov, A. Rosaev, E. Plávalová","doi":"10.1017/S1743921322000746","DOIUrl":"https://doi.org/10.1017/S1743921322000746","url":null,"abstract":"Abstract We have found three new members of the Rampo asteroids family: 2009HD95, 2010VO19, 2013JF69. We estimated the Yarkovsky semimajor axis drift rate. Based on the simulation results, estimates of the asteroid pairs’ age included in the family are obtained. In the scenario of the cascade disruption of the parent body of the asteroid (10321) Rampo, one can note the concentration of estimates of the pairs’ age to values of 900, 750, 500, and 250 kyr.","PeriodicalId":20590,"journal":{"name":"Proceedings of the International Astronomical Union","volume":"22 1","pages":"262 - 263"},"PeriodicalIF":0.0,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82081542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-01DOI: 10.1017/S1743921321001277
A. Fienga, L. Bigot, D. Mary, P. Deram, A. Di Ruscio, L. Bernus, M. Gastineau, J. Laskar
Abstract We give here a detailed description of the latest INPOP planetary ephemerides INPOP20a. We test the sensitivity of the Sun oblateness determination obtained with INPOP to different models for the Sun core rotation. We also present new evaluations of possible GRT violations with the PPN parameters β, γ and . With a new method for selecting acceptable alternative ephemerides we provide conservative limits of about 7.16 × 10-5 and 7.49 × 10-5 for β-1 and γ-1 respectively using the present day planetary data samples. We also present simulations of Bepi-Colombo range tracking data and their impact on planetary ephemeris construction. We show that the use of future BC range observations should improve these estimates, in particular γ. Finally, interesting perspectives for the detection of the Sun core rotation seem to be reachable thanks to the BC mission and its accurate range measurements in the GRT frame.
{"title":"Evolution of INPOP planetary ephemerides and Bepi-Colombo simulations","authors":"A. Fienga, L. Bigot, D. Mary, P. Deram, A. Di Ruscio, L. Bernus, M. Gastineau, J. Laskar","doi":"10.1017/S1743921321001277","DOIUrl":"https://doi.org/10.1017/S1743921321001277","url":null,"abstract":"Abstract We give here a detailed description of the latest INPOP planetary ephemerides INPOP20a. We test the sensitivity of the Sun oblateness determination obtained with INPOP to different models for the Sun core rotation. We also present new evaluations of possible GRT violations with the PPN parameters β, γ and . With a new method for selecting acceptable alternative ephemerides we provide conservative limits of about 7.16 × 10-5 and 7.49 × 10-5 for β-1 and γ-1 respectively using the present day planetary data samples. We also present simulations of Bepi-Colombo range tracking data and their impact on planetary ephemeris construction. We show that the use of future BC range observations should improve these estimates, in particular γ. Finally, interesting perspectives for the detection of the Sun core rotation seem to be reachable thanks to the BC mission and its accurate range measurements in the GRT frame.","PeriodicalId":20590,"journal":{"name":"Proceedings of the International Astronomical Union","volume":"24 1","pages":"31 - 51"},"PeriodicalIF":0.0,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80029862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-01DOI: 10.1017/S1743921321001344
Mahdi Jafari-Nadoushan
Abstract In the spin-orbit resonances, we assume that the orbit of the secondary asteroid around the primary is invariant, which is a reasonable assumption at first glance. Owing to the irregularity of asteroids’ geometry and their effect on the mutual orbit, this assumption should be revised. Therefore, we focus on a binary asteroid with a spherical primary and a secondary with an irregular shape. When the shape of a secondary asteroid is not a sphere, the gravitational interaction is important, and we should consider the interaction of orbit and spin. We generate fast Lyapunov indicator (FLI) maps for both spin-orbit resonance and spin-orbit coupling problems and investigate the effect of orbit alternation on the structure of phase space.
{"title":"A cartographic study of spin-orbit coupling in binary asteroids","authors":"Mahdi Jafari-Nadoushan","doi":"10.1017/S1743921321001344","DOIUrl":"https://doi.org/10.1017/S1743921321001344","url":null,"abstract":"Abstract In the spin-orbit resonances, we assume that the orbit of the secondary asteroid around the primary is invariant, which is a reasonable assumption at first glance. Owing to the irregularity of asteroids’ geometry and their effect on the mutual orbit, this assumption should be revised. Therefore, we focus on a binary asteroid with a spherical primary and a secondary with an irregular shape. When the shape of a secondary asteroid is not a sphere, the gravitational interaction is important, and we should consider the interaction of orbit and spin. We generate fast Lyapunov indicator (FLI) maps for both spin-orbit resonance and spin-orbit coupling problems and investigate the effect of orbit alternation on the structure of phase space.","PeriodicalId":20590,"journal":{"name":"Proceedings of the International Astronomical Union","volume":"58 1","pages":"158 - 164"},"PeriodicalIF":0.0,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83874405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-01DOI: 10.1017/S1743921321001290
E. Kuznetsov, O. Al-Shiblawi, V. Gusev
Abstract We have studied the probabilistic evolution of four candidates for young pairs of trans-Neptunian objects: 2003 QL91 – 2015 VA173, 1999 HV11 – 2015 VF172, 2002 CY154 – 2005 EW318 and 2013 SD101 – 2015 VY170 over 10 Myr in the past. All pairs belong to cold Classical Kuiper Belt objects. We concluded that the age of the considered pairs exceeds 10 Myr.
{"title":"Probabilistic evolution of pairs of trans-Neptunian objects in close orbits","authors":"E. Kuznetsov, O. Al-Shiblawi, V. Gusev","doi":"10.1017/S1743921321001290","DOIUrl":"https://doi.org/10.1017/S1743921321001290","url":null,"abstract":"Abstract We have studied the probabilistic evolution of four candidates for young pairs of trans-Neptunian objects: 2003 QL91 – 2015 VA173, 1999 HV11 – 2015 VF172, 2002 CY154 – 2005 EW318 and 2013 SD101 – 2015 VY170 over 10 Myr in the past. All pairs belong to cold Classical Kuiper Belt objects. We concluded that the age of the considered pairs exceeds 10 Myr.","PeriodicalId":20590,"journal":{"name":"Proceedings of the International Astronomical Union","volume":"34 1","pages":"165 - 170"},"PeriodicalIF":0.0,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89901108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-01DOI: 10.1017/S1743921322004392
Bumhyun Lee, Jing Wang, A. Chung, L. Ho, J. Molina, Yongjung Kim, Shun Wang, B. For, B. Koribalski, K. Spekkens, A. Bosma, B. Holwerda, L. Verdes-Montenegro
Abstract At least half of the local galaxies reside in galaxy groups, which indicates that the group is the common environment where galaxies evolve. Therefore, it is important to probe how significantly galaxies are affected by group environmental processes, in order to obtain a better understanding of galaxy evolution. We carried out a new CO imaging survey for 31 galaxies in the IC 1459 and NGC 4636 groups, using the Atacama Compact Array, to study the effect of the group environment on the molecular gas properties and the star formation activity. With our resolved CO data, combined with high-resolution H i images, we find asymmetric CO and H i distributions in the group galaxies. Compared to isolated galaxies, group members have relatively low molecular gas fraction and low star formation rate. These results suggest that the group environment can change the properties of cold gas components and star formation in group galaxies.
{"title":"The Impact of the Group Environment on the Molecular Gas and Star Formation Activity","authors":"Bumhyun Lee, Jing Wang, A. Chung, L. Ho, J. Molina, Yongjung Kim, Shun Wang, B. For, B. Koribalski, K. Spekkens, A. Bosma, B. Holwerda, L. Verdes-Montenegro","doi":"10.1017/S1743921322004392","DOIUrl":"https://doi.org/10.1017/S1743921322004392","url":null,"abstract":"Abstract At least half of the local galaxies reside in galaxy groups, which indicates that the group is the common environment where galaxies evolve. Therefore, it is important to probe how significantly galaxies are affected by group environmental processes, in order to obtain a better understanding of galaxy evolution. We carried out a new CO imaging survey for 31 galaxies in the IC 1459 and NGC 4636 groups, using the Atacama Compact Array, to study the effect of the group environment on the molecular gas properties and the star formation activity. With our resolved CO data, combined with high-resolution H i images, we find asymmetric CO and H i distributions in the group galaxies. Compared to isolated galaxies, group members have relatively low molecular gas fraction and low star formation rate. These results suggest that the group environment can change the properties of cold gas components and star formation in group galaxies.","PeriodicalId":20590,"journal":{"name":"Proceedings of the International Astronomical Union","volume":"39 1","pages":"136 - 139"},"PeriodicalIF":0.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80917649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-01DOI: 10.1017/S1743921322003957
B. Elmegreen, D. Hunter, Zorayda Martinez, Haylee N. Archer, C. Simpson, P. Cigan
Abstract Azimuthal variations in HI velocity dispersion do not correlate with variations in the star formation rate per unit area, SFR/A, suggesting that local star formation does not increase HI turbulence significantly. These variations are determined for each pixel in HI and FUV maps of THINGS and LITTLE THINGS galaxies by subtracting the average radial profiles from the measured quantities. The kinetic energy density and HI surface density increase slightly with SFR/A, suggesting that feedback goes into pushing the local dense gas around without increasing the velocity dispersion. We suggest that star formation feedback does not promote large-scale stability against gravitational forces through turbulence regulation, and that gravitational energy from recurrent instabilities drives turbulence on galactic scales.
{"title":"A search for correlations between turbulence and star formation in LITTLE THINGS and THINGS galaxies","authors":"B. Elmegreen, D. Hunter, Zorayda Martinez, Haylee N. Archer, C. Simpson, P. Cigan","doi":"10.1017/S1743921322003957","DOIUrl":"https://doi.org/10.1017/S1743921322003957","url":null,"abstract":"Abstract Azimuthal variations in HI velocity dispersion do not correlate with variations in the star formation rate per unit area, SFR/A, suggesting that local star formation does not increase HI turbulence significantly. These variations are determined for each pixel in HI and FUV maps of THINGS and LITTLE THINGS galaxies by subtracting the average radial profiles from the measured quantities. The kinetic energy density and HI surface density increase slightly with SFR/A, suggesting that feedback goes into pushing the local dense gas around without increasing the velocity dispersion. We suggest that star formation feedback does not promote large-scale stability against gravitational forces through turbulence regulation, and that gravitational energy from recurrent instabilities drives turbulence on galactic scales.","PeriodicalId":20590,"journal":{"name":"Proceedings of the International Astronomical Union","volume":"10 1","pages":"93 - 97"},"PeriodicalIF":0.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84593786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-01DOI: 10.1017/S1743921322004458
G. Gonz'alez-Tora, M. Wittkowski, B. Davies, B. Plez
Abstract Red supergiants (RSGs) are evolved massive stars in a stage preceding core-collapse supernova. Understanding evolved-phases of these cool stars is key to understanding the cosmic matter cycle of our Universe, since they enrich the cosmos with newly formed elements. However, the physical processes that trigger mass loss in their atmospheres are still not fully understood, and remain one of the key questions in stellar astrophysics. We use a new method to study the extended atmospheres of these cold stars, exploring the effect of a stellar wind for both a simple radiative equilibrium model and a semi-empirical model that accounts for a chromospheric temperature structure. We then can compute the intensities, fluxes and visibilities matching the observations for the different instruments at the Very Large Telescope Interferometer (VLTI). Specifically, when comparing with the atmospheric structure of HD 95687 based on published VLTI/AMBER data, we find that our model can accurately match these observations in the K-band, showing the enormous potential of this methodology to reproduce extended atmospheres of RSGs.
{"title":"The effect of winds in red supergiants: modeling for interferometry","authors":"G. Gonz'alez-Tora, M. Wittkowski, B. Davies, B. Plez","doi":"10.1017/S1743921322004458","DOIUrl":"https://doi.org/10.1017/S1743921322004458","url":null,"abstract":"Abstract Red supergiants (RSGs) are evolved massive stars in a stage preceding core-collapse supernova. Understanding evolved-phases of these cool stars is key to understanding the cosmic matter cycle of our Universe, since they enrich the cosmos with newly formed elements. However, the physical processes that trigger mass loss in their atmospheres are still not fully understood, and remain one of the key questions in stellar astrophysics. We use a new method to study the extended atmospheres of these cold stars, exploring the effect of a stellar wind for both a simple radiative equilibrium model and a semi-empirical model that accounts for a chromospheric temperature structure. We then can compute the intensities, fluxes and visibilities matching the observations for the different instruments at the Very Large Telescope Interferometer (VLTI). Specifically, when comparing with the atmospheric structure of HD 95687 based on published VLTI/AMBER data, we find that our model can accurately match these observations in the K-band, showing the enormous potential of this methodology to reproduce extended atmospheres of RSGs.","PeriodicalId":20590,"journal":{"name":"Proceedings of the International Astronomical Union","volume":"50 1","pages":"72 - 77"},"PeriodicalIF":0.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78521807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-01DOI: 10.1017/S1743921323000492
M. Bernini-Peron, W. Marcolino, A. Sander
Abstract B supergiants (BSGs) are evolved objects on the cool end of the line-driven wind regime. Studying their atmospheres provides important insights on the stellar wind physics of these objects and their evolutionary status. So far important features of their spectra, especially in the UV region, could not be reproduced consistently with atmosphere models. This translates directly into problems of our understanding of their wind properties. Here, we present new insights about the BSGs on the cooler side of the Bi-Stability Jump, corresponding to spectral types later than B1. Using UV and optical data, we analysed a sample of Galactic cool BSGs. Including for the first time X-rays and clumping the wind models, we show that the spectra of cool BSGs cannot be explained without X-rays, despite any clear detection of the target stars.
{"title":"Clumping and X-rays in cool B Supergiants","authors":"M. Bernini-Peron, W. Marcolino, A. Sander","doi":"10.1017/S1743921323000492","DOIUrl":"https://doi.org/10.1017/S1743921323000492","url":null,"abstract":"Abstract B supergiants (BSGs) are evolved objects on the cool end of the line-driven wind regime. Studying their atmospheres provides important insights on the stellar wind physics of these objects and their evolutionary status. So far important features of their spectra, especially in the UV region, could not be reproduced consistently with atmosphere models. This translates directly into problems of our understanding of their wind properties. Here, we present new insights about the BSGs on the cooler side of the Bi-Stability Jump, corresponding to spectral types later than B1. Using UV and optical data, we analysed a sample of Galactic cool BSGs. Including for the first time X-rays and clumping the wind models, we show that the spectra of cool BSGs cannot be explained without X-rays, despite any clear detection of the target stars.","PeriodicalId":20590,"journal":{"name":"Proceedings of the International Astronomical Union","volume":"24 1","pages":"200 - 201"},"PeriodicalIF":0.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73396643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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