Active regions on the surface of Comet 43P/Wolf-Harrington determined from its nongravitational effects

نویسنده

  • S. Szutowicz
چکیده

The nongravitational perturbations in the motion of the periodic comet Wolf-Harrington are investigated during its nine observable apparitions in the period 1924–1998. To explain the irregular variations in the nongravitational acceleration, two different models are considered and successfully used to link all the apparitions: a) Model of nucleus with the activation and deactivation of discrete outgassing sources on the surface; b) Forced precession model of the spin axis of the nucleus with an activity described by nonlinear changes of the perihelion shift of the gas production curve. The first model is represented by two slightly different orbital solutions in which the northern active region is persistent and the initiations and disappearances of two southern regions are responsible for the observed variability of the nongravitational acceleration. Profiles of the modelled gas production rates are compared with observed light curves of the comet and used for an estimation of the effective outgassing area and the activity level of the cometary nucleus. According to all employed models of the nongravitational acceleration similar shifts of the maximum of the comet activity with respect to successive perihelion passages over the whole examined interval of the motion have been detected. The model parameters describing physical properties of the comet nucleus such as the nucleus orientation, the localization and the size of the active regions or the oblateness of the nucleus are derived from numerical fitting of the models to positional observations of the comet.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Cometary Orbit Determination and Nongravitational Forces

The accuracies of the orbits and ephemerides for active comets are most often limited by imperfectly modeled rocket-like accelerations experienced by active comets as a result of the outgassing cometary nucleus near perihelion. The standard nongravitational acceleration model proposed by Marsden et al. (1973) has been updated by allowing the nucleus outgassing to act asymmetrically with respect...

متن کامل

Telescope Observations of the Nucleus of Comet 103 P / Hartley 2

We have used the Spitzer Space Telescope InfraRed Spectrograph (IRS) 22-μm peakup array to observe thermal emission from the nucleus and trail of comet 103P/Hartley 2, the target of NASA’s Deep Impact Extended Investigation (DIXI). The comet was observed on UT 2008 August 12 and 13, while 5.5 AU from the Sun. We obtained two 200 frame sets of photometric imaging over a 2.7 hr period. To within ...

متن کامل

Evaluation of incubation temperatures on DNA damages of the Caspian trout (Salmo trutta caspius Kessler, 1877) single cells through developmental stages by Comet assay

Caspian trout (Salmo trutta caspius Kessler, 1877) is an endemic migratory subspecies in the Caspian Sea, possessing ecologic-economic and biodiversity greatly value. Among habitat factors, temperature and its possible effects on the Caspian trout genome were considered in this research. During Embryonic developmental stages (fertilization–hatching), genomic alterations of single cells were ass...

متن کامل

Oblate spheroid model of nucleus of Comet 46 P / Wirtanen

An improved forced-precession model of Comet 46P/Wirtanen is presented. The nongravitational motion of the comet has been investigated based on the forced precession model of the rotating cometary nucleus. The least squares method applied to observational equations allows us to determine six basic nongravitational parameters: A, η, I, φ, f p , and s together with six orbital elements. The solut...

متن کامل

Ginseng Use in Medicine: Perspectives on CNS Disorders

Ginseng, the root of Panax species, is a well-known folk medicine. It has been used as traditional herbal medicine in China, Korea and Japan for thousands of years and today is a popular and worldwide used natural medicine. The active ingredients of ginseng are ginsenosides which are also called ginseng saponins. Recently, there is increasing evidence in the literature on the pharmacological an...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2000