J/A+A/692/A86ivo://CDS.VizieR/J/A+A/692/A86doi:10.26093/cds/vizier.36920086CDSHoai D.T.Winters J.M.Nhung P.T.Darriulat P.Le Bertre T.2025-02-26T20:03:00Z2024-12-04T07:32:21ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frs-starslate-type-starsinterferometryradio-astronomyNew observations are presented of millimetre line emissions of the circumstellar envelope (CSE) of the asymptotic giant branch (AGB) star chi Cygni, using the recently upgraded NOEMA array. chi Cygni is an S-type Mira variable, at the border between oxygen-rich and carbon-rich stars. It has been observed for over 40 years to display features that suggest evidence for the strong role played by pulsation associated shock waves in the generation of its wind. These new observations provide evidence of a bright H^12^CN(3-2) line emission confined to the very close neighbourhood of the star; however, this emission appears significantly more extended in 2024 than in 2023. The interpretation of such variability in terms of maser emission has been considered and found to raise significant unanswered questions. Moreover, other unexpected features are observed in the very close neighbourhood of the star, including low Si^16^O(6-5)/Si^17^O(6-5), ^28^SiO(5-4)/^29^SiO(5-4), and ^12^CO(2-1)/^13^CO(2-1) line emission ratios. We discuss several features, which possibly confirm the important role played by shocks: a measurement of the SiO(5-4)/SiO(6-5) emission ratio; the observation of a recent mass ejection, particularly enhanced in the north-western red-shifted octant, which has left a depression in its wake; patterns of enhanced CO(2-1) line emission, which suggest an interpretation in terms of episodic outflows, on a time scale of a few decades, enhanced over solid angles associated with the surface of convective cells. Unravelling the mechanisms underlying such newly observed features is very challenging. Thus, a confirmation of the reported observations with improved sensitivity and angular resolution would be highly welcome. The observation of SiO maser emission in the (nu=1,J=6-5) transition is reported for the first time.2024A&A...692A..86Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/692/A86CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/692/A86https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/692/A86http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/692/A86https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/692/A86https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/692/A86http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/692/A86GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/692/A86/list (List of fits datacubes)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/692/A86/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/692/A86/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/692/A86/list?GETtext/xml+votable180.050000true297.6411632.913780.0055555555555555566/14457https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/692/A86?format=asciiRadiodefaultJ/A+A/692/A86/listList of fits datacubesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintNzNumber of slicesmeta.numberintbVRADLower value of VRAD intervalm/sphys.velocintBVRADUpper value of VRAD intervalm/sphys.velocintdVRADVRAD resolutionm/sspect.resolutionintsizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fits