English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Infrared carbon stars without visible counterparts are generally known asextreme carbon stars. We have selected a subset of these stars with absorptionfeatures in the 10-13 $\mu$m range, which has been tentatively attributed tosilicon carbide (SiC). We add three new objects meeting these criterion to theseven previously known, bringing our total sample to ten sources. We alsopresent the result of radiative transfer modeling for these stars, comparingthese results to those of previous studies. In order to constrain modelparameters, we use published mass-loss rates, expansion velocities andtheoretical dust condensation models to determine the dust condensationtemperature. These show that the inner dust temperatures of the dust shells forthese sources are significantly higher than previously assumed. This alsoimplies that the dominant dust species should be graphite instead of amorphouscarbon. In combination with the higher condensation temperature we show thatthis results in a much higher acceleration of the dust grains than would beexpected from previous work. Our model results suggest that the very opticallythick stage of evolution does not coincide with the timescales for thesuperwind, but rather, that this is a very short-lived phase. Additionally, wecompare model and observational parameters in an attempt to find anycorrelations. Finally, we show that the spectrum of one source, IRAS17534$-$3030, strongly implies that the 10-13 $\mu$m feature is due to a solidstate rather than a molecular species.

Silicon carbide absorption features: dust formation in the outflows of extreme carbon stars