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<div style="margin-top:0px; margin-bottom:0px">Dear all,</div>
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<div style="margin-top:0px; margin-bottom:0px">our next EO meeting will take place <b>on Thursday, 10th of February,</b> at 13:15 (CET). </div>
<div style="margin-top:0px; margin-bottom:0px">The speaker is <b>Quentin Pognan</b>, PhD student of Anders Jerkstrand (Stockholm University), working on light curves and spectra of kilonovae. He is going to talk about his recent work on this topic.</div>
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<div style="margin-top:0px; margin-bottom:0px"><b>To join the meeting:</b></div>
<div style="margin-top:0px; margin-bottom:0px">https://stockholmuniversity.zoom.us/j/65883589027?pwd=RGxJOUVQWmNtMlZFMUIwaHRabkExdz09</div>
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<div style="margin-top:0px; margin-bottom:0px"><b>Meeting ID:</b> 658 8358 9027</div>
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<div style="margin-top:0px; margin-bottom:0px">Below is title and abstract of the talk.</div>
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<div style="margin-top:0px; margin-bottom:0px"><b>Title: </b><i style="font-size:12pt; font-family:Calibri,Helvetica,sans-serif,EmojiFont,"Apple Color Emoji","Segoe UI Emoji",NotoColorEmoji,"Segoe UI Symbol","Android Emoji",EmojiSymbols">The validity of the
LTE and steady-state approximations for nebular phase kilonovae </i></div>
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<div style="margin-top:0px; margin-bottom:0px"><b>Abstract: </b><i style="font-size:12pt; font-family:Calibri,Helvetica,sans-serif,EmojiFont,"Apple Color Emoji","Segoe UI Emoji",NotoColorEmoji,"Segoe UI Symbol","Android Emoji",EmojiSymbols"><br>
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<div style="margin-top:0px; margin-bottom:0px"><i style="font-family:Calibri,Helvetica,sans-serif,EmojiFont,"Apple Color Emoji","Segoe UI Emoji",NotoColorEmoji,"Segoe UI Symbol","Android Emoji",EmojiSymbols; text-align:justify">Kilonovae (KN) following a binary
neutron star merger are expected to enter a non-local thermodynamic equilibrium (NLTE) regime several days after merger, as ejecta densities rapidly fall. Accompanying this transition away from local thermodynamic equilibrium (LTE), is a transition to a ‘nebular’
phase, where spectra are dominated by emission lines, as opposed to scattering lines over a quasi-blackbody continuum. The nebular phase is initially in a ‘steady-state’ regime, until thermal reprocessing timescales become long, at which point the temperature
and ionization states need to be evolved time-dependently. Since nebular phase spectra offer a possibility of element identification in KN, it is interesting to study the onset and significance of time-dependent effects. I will present a study into these effects
conducted using the spectral synthesis code SUMO, and demonstrate that time-dependent calculations may be necessary for certain ejecta parameters. I will also briefly present some ongoing work on the importance of NLTE calculations for post-peak KN, with a
focus on consequences for expansion opacities.</i><br>
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<div style="margin-top:0px; margin-bottom:0px">Hope to see you there!</div>
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<div style="margin-top:0px; margin-bottom:0px"><span style="font-family:Calibri,Helvetica,sans-serif,serif,EmojiFont">Ana Sagués Carracedo & Davide Gizzi</span><br>
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