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

We report the detection of two lines at millimetre wavelengths towards theimmediate surroundings of the post-giant and most likely post-common-envelopestar HD101584 using high-angular-resolution ALMA observations. Thecircumstellar environment of this object is rich in different molecularspecies, but we find no viable identifications in terms of molecular lines.  We aim to determine whether or not these lines can be attributed to theRydberg transitions -- X30alpha and X26alpha -- of neutral atoms of elementsheavier than carbon.  A simple model in strict local thermodynamic equilibrium for a warm-gasenvironment of the moderate-temperature star (T_eff about 8500 K) wasconstructed to corroborate our findings. A geometrically thin, disc-likegeometry seen face-on was chosen and a distance of 1 kpc.  The observed flux densities of the lines and the continuum at 232 and 354 GHzcan be reproduced using 10^(-3) M_sun of gas at a temperature of about 2800 Kand a hydrogen density of about 10^(12) cm(-3), assuming solar abundances forthe elements. The gas lies within a distance of about 5 au from the star(assuming a distance of 1 kpc). The ionisation fraction is low, about3x10^(-5). The origin of such a region is not clear, but it may be related to acommon-envelope-evolution phase. With these conditions, the line emissions aredominated by Rydberg transitions within the stable isotopes of Mg. A turbulentvelocity field in the range 5.5 - 7.5 km s^(-1) is required to fit the Gaussianline shapes. An upper limit to the average magnetic field in the line-emittingregion of 1G is set using the Zeeman effect in these lines.  We speculate that Rydberg transitions of heavy elements may be an interestingprobe for the close-in environments of other moderate-temperature objects likeAGB stars, red supergiants, yellow hypergiants, and binaries of various types.

Heavy-element Rydberg transition line emission from the post-giant-evolution star HD101584