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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

FU Ori-type stars are young stellar objects (YSOs) experiencing luminosityoutbursts by a few orders of magnitude, which last for $\sim$$10^2$ years. Adozen of FUors are known up to date, but many more currently quiescent YSOscould have experienced such outbursts in the last $\sim$$10^3$ years. To findobservational signatures of possible past outbursts, we utilise ANDES, RADMC-3Dcode as well as CASA ALMA simulator to model the impact of the outburst on thephysical and chemical structure of typical FU Ori systems and how it translatesto the molecular lines' fluxes. We identify several combinations of molecularlines that may trace past FU Ori objects both with and without envelopes. Themost promising outburst tracers from an observational perspective are themolecular flux combinations of the N$_{2}$H$^{+}$ $J=3-2$, C$^{18}$O $J = 2-1$,H$_2$CO $(J_{\rm K_a, K_c}) = 4_{04}-3_{03}$, and HCN $J = 3-2$ lines. Weanalyse the processes leading to molecular flux changes and show that they arelinked with either thermal desorption or enhanced chemical reactions in themolecular layer. Using observed CO, HCN, N$_2$H$^+$ and H$_2$CO line fluxesfrom the literature, we identify ten nearby disc systems that might haveundergone FU Ori outbursts in the past $\sim$$10^3$ years: [MGM2012] 556,[MGM2012] 371 and [MGM2012] 907 YSOs in L1641, Class II protoplanetary discsaround CI Tau, AS 209 and IM Lup and transitional discs DM Tau, GM Aur, LkCa 15and J1640-2130.

Observational Chemical Signatures of the Past FU Ori Outbursts