Thermodynamics of the Condensation of Dust Grains in Wolf-Rayet Stellar Winds. (arXiv:1912.10020v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Gupta_A/0/1/0/all/0/1">Anuj Gupta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sahijpal_S/0/1/0/all/0/1">Sandeep Sahijpal</a>
Wolf-Rayet (WR) stars are the evolutionary phases of very massive stars prior
to the final supernova explosion stage. These stars lose substantial mass
during WN and WC stages. The mass losses are associated with diverse elemental
and isotopic signatures that represent distinct stellar evolutionary processes.
The WR strong winds can host environments for condensation of dust grains with
diverse compositions. The condensation of dust in the outflows of the massive
stars is supported by several observations. The present work is an attempt to
develop a theoretical framework of thermodynamics associated with the
condensation of dust grains in the winds of WN and WC phases. A novel numerical
code has been developed for dust condensation. Apart from the equilibrium dust
condensation calculations, we have attempted, perhaps for the first time, a set
of non-equilibrium scenarios for dust condensation in various WR stages. These
scenarios differ in terms of the magnitude of the non-equilibrium state,
defined in terms of a simulation non-equilibrium parameter. Here, we attempt to
understand the sensitivity of the simulation non-equilibrium parameter on the
condensation sequence of dust grains. In general, we found that mostly C
(graphite), TiC, SiC, AlN, CaS and Fe-metal are condensed in WR winds. The
extent of non-equilibrium influences the relative proportions of earliest dust
condensate compared to the condensates formed at later stages subsequent to the
cooling of the gas. The results indicate that dust grains condensed in the WC
phase may substantially contribute carbon-rich dust grains to the interstellar
medium.
Wolf-Rayet (WR) stars are the evolutionary phases of very massive stars prior
to the final supernova explosion stage. These stars lose substantial mass
during WN and WC stages. The mass losses are associated with diverse elemental
and isotopic signatures that represent distinct stellar evolutionary processes.
The WR strong winds can host environments for condensation of dust grains with
diverse compositions. The condensation of dust in the outflows of the massive
stars is supported by several observations. The present work is an attempt to
develop a theoretical framework of thermodynamics associated with the
condensation of dust grains in the winds of WN and WC phases. A novel numerical
code has been developed for dust condensation. Apart from the equilibrium dust
condensation calculations, we have attempted, perhaps for the first time, a set
of non-equilibrium scenarios for dust condensation in various WR stages. These
scenarios differ in terms of the magnitude of the non-equilibrium state,
defined in terms of a simulation non-equilibrium parameter. Here, we attempt to
understand the sensitivity of the simulation non-equilibrium parameter on the
condensation sequence of dust grains. In general, we found that mostly C
(graphite), TiC, SiC, AlN, CaS and Fe-metal are condensed in WR winds. The
extent of non-equilibrium influences the relative proportions of earliest dust
condensate compared to the condensates formed at later stages subsequent to the
cooling of the gas. The results indicate that dust grains condensed in the WC
phase may substantially contribute carbon-rich dust grains to the interstellar
medium.
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