* Astronomy

Members Login
Post Info TOPIC: Comet Shoemaker-Levy 9


L

Posts: 131433
Date:
RE: Comet Shoemaker-Levy 9
Permalink  
 


Herschel links Jupiters water to comet impact

ESA's Infrared Space Observatory was launched in 1995 and was the first to detect and study water in Jupiter's upper atmosphere. It was widely speculated that comet Shoemaker-Levy 9 may have been the origin of this water, but direct proof was missing.
Scientists were able to exclude an internal source, such as water rising from deeper within the planet's atmosphere, because it is not possible for water vapour to pass through the 'cold trap' that separates the stratosphere from the visible cloud deck in the troposphere below.
Thus the water in Jupiter's stratosphere must have been delivered from outside. But determining its origin had to wait more than 15 years, until Herschel used its sensitive infrared eyes to map the vertical and horizontal distribution of water's chemical signature.

Read more



__________________


L

Posts: 131433
Date:
Permalink  
 

Title: The physics of granular flow and the tidal disruption of comet Shoemaker-Levy 9
Authors: Naor Movshovitz (1), Erik Asphaug (1), Donald Korycansky (1) ((1) University of California, Santa Cruz)

We advance the modelling of rubble-pile solid bodies by re-examining the tidal breakup of comet Shoemaker-Levy 9, an event that occurred during a 1.33 Jupiter radii encounter with that planet in July 1992. Tidal disruption of the comet nucleus led to a chain of sub-nuclei about 100-1000 m in diameter; these went on to collide with the planet two years later (Chodas & Yeomans 1996). They were intensively studied prior to and during the collisions, making SL9 the best natural benchmark for physical models of small body disruption. For the first time in the study of this event, we use numerical codes treating rubble-piles as collections of polyhedra (Korycansky & Asphaug 2009). This introduces forces of dilatation and friction, and inelastic response. As in our previous studies (Asphaug & Benz 1994,1996) we conclude that the progenitor must have been a rubble-pile, and we obtain approximately the same pre-breakup diameter (about 1.5 km) in our best fits to the data. We find that the inclusion of realistic fragment shapes leads to grain locking and dilatancy, so that even in the absence of friction or other dissipation we find that disruption is overall more difficult than in our spheres-based simulations. We constrain the comet's bulk density at about 300-400 kg/m³, half that of our spheres-based predictions and consistent with recent estimates derived from spacecraft observations.

Read more (913kb, PDF)



__________________


L

Posts: 131433
Date:
Permalink  
 

The first impact occurred at 20:13 UTC on July 16, 1994



__________________


L

Posts: 131433
Date:
Permalink  
 

Anniversary of the Comet Shoemaker-Levy 9 near-Jupiter flyby (0.0008 AU) on 8th July, 1992.

David Levy - Comet Finder



__________________


L

Posts: 131433
Date:
Shoemaker-Levy 9 event
Permalink  
 


Title: Numerical Modeling of the 2009 Impact Event on Jupiter
Authors: Jarrad W. T. Pond, Csaba Palotai, Travis Gabriel, Donald G. Korycansky, Joseph Harrington, Noemi Rebeli

We have investigated the 2009 July impact event on Jupiter using the ZEUS-MP 2 three-dimensional hydrodynamics code. We studied the impact itself and the following plume development. Eight impactors were considered: 0.5 km and 1 km porous (rho = 1.760 g cm^{-3}) and non-porous (rho = 2.700 g cm^{-3}) basalt impactors, and 0.5 km and 1 km porous (rho = 0.600 g cm^{-3}) and non-porous rho = 0.917 g cm^{-3}) ice impactors. The simulations consisted of these bolides colliding with Jupiter at an incident angle of theta = 69 degrees from the vertical and with an impact velocity of v = 61.4 km s^{-1}. Our simulations show the development of relatively larger, faster plumes created after impacts involving 1 km diameter bodies. Comparing simulations of the 2009 event with simulations of the Shoemaker-Levy 9 events reveals a difference in plume development, with the higher incident angle of the 2009 impact leading to a shallower terminal depth and a smaller and slower plume. We also studied the amount of dynamical chaos present in the simulations conducted at the 2009 incident angle. Compared to the chaos of the SL9 simulations, where \theta is approximately 45 degrees, we find no significant difference in chaos at the higher 2009 incident angle.

Read more (7570kb, PDF)



__________________


L

Posts: 131433
Date:
RE: Comet Shoemaker-Levy 9
Permalink  
 


The comet Shoemaker-Levy 9 was discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy. Shoemaker-Levy 9, at the time captured by and orbiting Jupiter, was located on the night of March 24, 1993, in a photograph taken with the 40 centimetres Schmidt telescope at the Palomar Observatory in California.
Read more 



__________________


L

Posts: 131433
Date:
Permalink  
 

Fragment G of Comet Shoemaker-Levy 9 struck Jupiter on July 18, 1994, at 07:33 UTC. This impact created a giant dark spot over 12,000 km across, and was estimated to have released an energy equivalent to 6,000,000 megatons of TNT (600 times the world's nuclear arsenal).
Read more



__________________


L

Posts: 131433
Date:
Permalink  
 

Comet Shoemaker-Levy 9 (formally designated D/1993 F2, nicknamed String of Pearls for its appearance) was a comet that broke apart and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of solar system objects.
The first impact occurred at 20:13 UTC on July 16, 1994, when fragment A of the nucleus slammed into Jupiter's southern hemisphere at a speed of about 60 km/s.

Read more



__________________


L

Posts: 131433
Date:
Permalink  
 

Comet Shoemaker-Levy 9 made a close flyby of Jupiter (0.0008 AU) on the 8th July, 1992.



__________________


L

Posts: 131433
Date:
Permalink  
 

The comet was discovered by astronomers Carolyn and Eugene M. Shoemaker, David Levy and Philippe Bendjoya from France. Shoemaker-Levy 9, at the time captured by and orbiting Jupiter, was located on the night of March 24, 1993, in a photograph taken with the 40 centimetres Schmidt telescope at the Palomar Observatory in California.
Read more 



__________________
1 2  >  Last»  | Page of 2  sorted by
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard