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

Our current insights into the circumstellar chemistry of asymptotic giantbranch (AGB) stars are largely based on studies of carbon-rich stars and starswith high mass-loss rates. In order to expand the current molecular inventoryof evolved stars we present a spectral scan of the nearby, oxygen-rich star RDor, a star with a low mass-loss rate ($\sim2\times10^{-7}M_{\odot}$/yr). Wecarried out a spectral scan in the frequency ranges 159.0-321.5GHz and338.5-368.5 GHz (wavelength range 0.8-1.9mm) using the SEPIA/Band-5 and SHeFIinstruments on the APEX telescope and we compare it to previous surveys,including one of the oxygen-rich AGB star IK Tau, which has a high mass-lossrate ($\sim5\times10^{-6}M_{\odot}$/yr). The spectrum of R Dor is dominated byemission lines of SO$_2$ and the different isotopologues of SiO. We also detectCO, H$_2$O, HCN, CN, PO, PN, SO, and tentatively TiO$_2$, AlO, and NaCl.Sixteen out of approximately 320 spectral features remain unidentified. Amongthese is a strong but previously unknown maser at 354.2 GHz, which we suggestcould pertain to H$_2$SiO, silanone. With the exception of one, none of theseunidentified lines are found in a similarly sensitive survey of IK Tauperformed with the IRAM 30m telescope. We present radiative transfer models forfive isotopologues of SiO ($^{28}$SiO, $^{29}$SiO, $^{30}$SiO, Si$^{17}$O,Si$^{18}$O), providing constraints on their fractional abundance and radialextent. We derive isotopic ratios for C, O, Si, and S and estimate that R Dorlikely had an initial mass in the range 1.3-1.6$M_{\odot}$, in agreement withearlier findings based on models of H$_2$O line emission. From the presence ofspectral features recurring in many of the measured thermal and maser emissionlines we tentatively identify up to five kinematical components in the outflowof R Dor, indicating deviations from a smooth, spherical wind.

Circumstellar environment of the M-type AGB star R Dor. APEX spectral scan at $159.0-368.5$ GHz