* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Asteroids 2013 -> Asteroid rotation
Post Info TOPIC: Asteroid rotation
Blobrana


L

Posts: 131433
Date:
RE: Asteroid rotation
Permalink  
 

Title: 313 new asteroid rotation periods from Palomar Transient Factory observations
Author: Chan-Kao Chang, Wing-Huen Ip, Hsing-Wen Lin, Yu-Chi Cheng, Chow-Choong Ngeow, Ting-Chang Yang, Adam Waszczak, Shrinivas R. Kulkarni, David Levitan, Branimir Sesar, Russ Laher, Jason Surace, Thomas. A. Prince, the PTF Team

A new asteroid rotation period survey have been carried out by using the Palomar Transient Factory (PTF). Twelve consecutive PTF fields, which covered an area of 87 deg2 in the ecliptic plane, were observed in R band with a cadence of ~20 min during February 15--18, 2013. We detected 2500 known asteroids with a diameter range of 0.5 km \leq D \leq 200 km. Of these, 313 objects had highly reliable rotation periods and exhibited the "spin barrier" at ~2 hours. In contrast to the flat spin rate distribution of the asteroids with 3 km \leq D \leq 15 km shown by Pravec et al. (2008), our results deviated somewhat from a Maxwellian distribution and showed a decrease at the spin rate greater than 5 rev/day. One super-fast-rotator candidate and two possible binary asteroids were also found in this work.

Read more (1199kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: Asteroid rotation excitation by subcatastrophic impacts
Authors: T. Henych, P. Pravec

Photometric observations of asteroids show that some of them are in non-principal axis rotation state (free precession), called tumbling. Collisions between asteroids have been proposed as a possible asteroid rotation excitation mechanism. We simulated subcatastrophic collisions between asteroids of various physical and material parameters to find out whether they could be responsible for the excited rotation. For every simulated target body after the collision, we computed its rotational lightcurve and we found that tumbling was photometrically detectable for the rotational axis misalignment angle \beta greater than about 15 deg. We found that subcatastrophic collisions are a plausible cause of non-principal axis rotation for small slowly rotating asteroids. The determining parameter is the ratio of the projectile orbital angular momentum to the target rotational angular momentum and we derived an approximate relation between this ratio and the angle \beta. We also compared the limiting energy for the onset of tumbling with the shattering energy. Slowly rotating asteroids of diameter 100 m and larger can be rotationally excited by collisions with energies below the shattering limit.

Read more (82kb, PDF)



__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Asteroids 2013 -> Asteroid rotation


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard