Time-scales to reach chemical equilibrium in ices at snowline distance around compact objects: the influence of accretion mass in the central object

Author(s)

Carvalho, G. A. ^[1] ; Pilling, S. ^[1]

Affiliation

^[1] Univ Vale Paraiba UNIVAP, Inst Pesquisa & Desenvolvimento IP&D, Av Shishima Hifumi 2911, BR-12244000 Sao Jose Dos Campos, SP - Brazil

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 503, n. 2, p. 2973-2978, MAY 2021.
• Web of Science Citations: 0

Abstract

In this work, we analyse soft X-ray emission due to mass accretion on to compact stars and its effects on the time-scale to reach chemical equilibrium of eventual surrounding astrophysical ices exposed to that radiation. Reaction time-scales due to soft X-ray in water-rich and pure ices of methanol, acetone, acetonitrile, formic acid, and acetic acid were determined. For accretion rates in the range (m) over dot = 10(-12)-10(-8) M-circle dot yr(-1) and distances in the range 1-3 LY from the central compact objects, the time-scales lie in the range 10-10(8) yr, with shorter time-scales corresponding to higher accretion rates. Obtained time-scales for ices at snow-line distances can be small when compared to the lifetime (or age) of the compact stars, showing that chemical equilibrium could have been achieved. Time-scales for ices to reach chemical equilibrium depend on X-ray flux and, hence, on accretion rate, which indicates that systems with low accretion rates may not have reached chemical equilibrium. (AU)

• FAPESP's process: 09/18304-0 - Synthesis and degradation of prebiotic molecular species at planetary atmospheres, comets and interstellar ice analogs
• Grantee: Sergio Pilling Guapyassu de Oliveira
• Support Opportunities: Research Grants - Young Investigators Grants