* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Asteroids 2012 -> Yarkovsky effect
Post Info TOPIC: Yarkovsky effect
Blobrana


L

Posts: 131433
Date:
RE: Yarkovsky effect
Permalink  
 

Title: The Yarkovsky and YORP Effects
Author: D. Vokrouhlicky, W. F. Bottke, S. R. Chesley, D. J. Scheeres, T. S. Statler

The Yarkovsky effect describes a small but significant force that affects the orbital motion of meteoroids and asteroids smaller than 30-40 kilometres in diameter. It is caused by sunlight; when these bodies heat up in the Sun, they eventually re-radiate the energy away in the thermal waveband, which in turn creates a tiny thrust. This recoil acceleration is much weaker than solar and planetary gravitational forces, but it can produce measurable orbital changes over decades and substantial orbital effects over millions to billions of years. The same physical phenomenon also creates a thermal torque that, complemented by a torque produced by scattered sunlight, can modify the rotation rates and obliquities of small bodies as well. This rotational variant has been coined the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. During the past decade or so, the Yarkovsky and YORP effects have been used to explore and potentially resolve a number of unsolved mysteries in planetary science dealing with small bodies. Here we review the main results to date, and preview the goals for future work.

Read more (734kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: Near Earth Asteroids with measurable Yarkovsky effect
Authors: D. Farnocchia, S. R. Chesley, D. Vokrouhlicky, A. Milani, F. Spoto

We seek evidence of the Yarkovsky effect among Near Earth Asteroids (NEAs) by measuring the Yarkovsky-related orbital drift from the orbital fit. To prevent the occurrence of unreliable detections we employ a high precision dynamical model, including the Newtonian attraction of 16 massive asteroids and the planetary relativistic terms, and a suitable astrometric data treatment. We find 21 NEAs whose orbital fits show a measurable orbital drift with a signal to noise ratio (SNR) greater than 3. The best determination is for asteroid (101955) 1999 RQ36, resulting in the recovery of one radar apparition and an orbit improvement by two orders of magnitude. In addition, we find 16 cases with a lower SNR that, despite being less reliable, are good candidates for becoming stronger detections in the future. In some cases it is possible to constrain physical quantities otherwise unknown by means of the detected orbital drift. Furthermore, the distribution of the detected orbital drifts shows an excess of retrograde rotators that can be connected to the delivery mechanism from the most important NEA feeding resonances and allows us to infer the distribution for NEAs obliquity. We discuss the implications of the Yarkovsky effect for impact predictions. In particular, for asteroid (29075) 1950 DA our results favour a retrograde rotation that would rule out an impact in 2880.

Read more (127kb, PDF)



__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Asteroids 2012 -> Yarkovsky effect


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard