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THE EVOLUTION OF PLANETARY NEBULAE(PN) AND FADING TIME ACCORDING TO SYNTHETIC MODEL
نشوء السدم الكوكبية (PN) وزمن الخفوت وفقا الى النموذج التركيبي

Authors: Sundus A.Abdullah سندس عبد العباس عبدالله --- Nedera A. Ali نذيرة عباس علي --- Muhamed A.Abutaib محمد احمد ابو الطيب
Journal: Iraqi Journal of Science المجلة العراقية للعلوم ISSN: 00672904/23121637 Year: 2012 Volume: 53 Issue: 1 Pages: 209-214
Publisher: Baghdad University جامعة بغداد

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Abstract

Planetary nebulae (PN) represents the short phase in the life of stars with masses (0.89-7) M☉. Several physical processes taking place during the red giant phase of low and intermediates-mass stars. These processes include :1) The regular (early ) wind and the envelope ejection, 2) The thermal pulses during Asymptotic Giant Branch (AGB ) phase. In this paper it is briefly discussed how such processes affect the mass range of Planetary Nebulae(PN) nuclei(core) and their evolution, and the PN life time, and fading time for the masses which adopted. The Synthetic model is adopted. The envelope mass of star (MeN ) and transition time (ttr) calculated respectively for the parameter (MeR =1.5,2, 3×10-3 M☉). Another time scale is of capital importance for the understanding of PN and their nuclei, it is the fading time ( tf). The results indicated that for each observed nebulae( ttr < tPN) also the fading time is sensitive to mass core(MH) of star, the mass with 1.2 M☉ takes only (25 yr ) to fading, while the mass with (0.66 M☉) takes about ( 4715 yr) years to fading. The calculations showed that (ttr) increases with the increasing of final mass( Mf). The initial nebulae radius will also increase with (Mf) thus will correlate with the location of nucleus on the HR diagram.

السدم الكوكبية تمثل مرحلة قصيرة من حياة النجوم التي كتلها تتراوح بين(0.89 -7) كتلة شمسية(M☉). هنالك عدة عمليات فيزيائية تحدث خلال مرحلة نجوم العمالقة الحمر ذات الكتل الواطئة والوسط. هذه العمليات تحدث في طورين 1- المرحلة المبكرة المنتظمة ونزع الغلاف 2-مرحلة النبضات الحرارية خلال طور التقارب العملاق AGB.

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