<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi all,<div class=""><br class=""></div><div class="">this Thursday (13:00-14:00) we will have two talks at our EO meeting:</div><div class=""><br class=""></div><div class="">1) <b class="">Ulrich Nöbauer</b> will talk about:</div><div class=""><br class=""></div><div class=""><div class="">"Type Ia supernovae within dense carbon-oxygen rich envelopes: a model</div><div class="">for 'Super-Chandrasekhar' explosions?"</div><div class=""><br class=""></div><div class=""><i class="">We investigate the consequences of fairly normal Type Ia supernovae</i></div><div class=""><i class="">being embedded in compact and dense envelopes of carbon and oxygen</i></div><div class=""><i class="">rich circumstellar material by means of detailed radiation</i></div><div class=""><i class="">hydrodynamic simulations. Our main focus rests on exploring the</i></div><div class=""><i class="">effects of the interaction between ejecta and circumstellar material</i></div><div class=""><i class="">on the ejecta evolution and the broad-band light curve. In our</i></div><div class=""><i class="">calculations, we find that a strong reverse shock efficiently</i></div><div class=""><i class="">decelerates and compresses the ejecta material. This leads to a</i></div><div class=""><i class="">significant broadening of the optical light curve, a longer rise to</i></div><div class=""><i class="">maximum and a slower decline in the tail phase. During the</i></div><div class=""><i class="">interaction, substantial radiative energy is generated, which mostly</i></div><div class=""><i class="">emerges in the extreme ultraviolet and X-ray regime. Only if</i></div><div class=""><i class="">reprocessing due to radiation--matter interactions is very efficient,</i></div><div class=""><i class="">a significant boost in the optical light curve is observed. We discuss</i></div><div class=""><i class="">these findings in particular in the context of the super-luminous</i></div><div class=""><i class="">event SN 2009dc. As our calculations are able to reproduce a number of</i></div><div class=""><i class="">its peculiar properties, we conclude that the flavour of the</i></div><div class=""><i class="">interaction scenario investigated in this work constitutes a promising</i></div><div class=""><i class="">candidate to explain such 'Super-Chandrasekhar' supernovae.</i></div></div><div class=""><br class=""></div><div class="">2) <b class="">Suhail Dhawan</b> will present:</div><div class=""><br class=""></div><div class=""><div class="">"Near Infrared and bolometric properties of fast-declining SN Ia</div><div class="">indicate sub-Chandra progenitors"</div><div class=""><br class=""></div><div class=""><i class="">Dedicated searches for Type Ia supernovae (SN~Ia) have discovered</i></div><div class=""><i class="">several classes exhibiting photometric and spectroscopic</i></div><div class=""><i class="">peculiarities. In this study, we characterise the diversity in the</i></div><div class=""><i class="">near infrared (NIR) and bolometric properties of the class of SN~Ia</i></div><div class=""><i class="">with fast optical decline rates ($\Delta m_{15}$ \textgreater 1.6) and</i></div><div class=""><i class="">compare them to normal ($\Delta m_{15}$ $\leq$ 1.6) SN~Ia.</i></div><div class=""><i class="">Fast-declining show a large range of peak bolometric luminosities</i></div><div class=""><i class="">($L_{max}$ differing by upto a factor of $\sim$ 8). The SNe appear to</i></div><div class=""><i class="">be split into two groups based on their $L_{max}$. All fast-declining</i></div><div class=""><i class="">SN~Ia with $L_{max}$ \textless 0.3$10^{43}ergs^{-1}$ are</i></div><div class=""><i class="">spectroscopically classified as 91bg-like and show only a single NIR</i></div><div class=""><i class="">peak. SNe with $L_{max}$ \textgreater 0.5 $10^{43}ergs^{-1}$ appear to</i></div><div class=""><i class="">smoothly connect to normal SN~Ia. The total ejecta mass ($M_{ej}$)</i></div><div class=""><i class="">values for SNe with enough late time data are $\lesssim$ 1</i></div><div class=""><i class="">$M_{\odot}$, indicating a sub-Chandrasekhar mass progenitor for these</i></div><div class=""><i class="">SNe.</i></div></div><div class=""><br class=""></div><div class="">%%%%%%%%%%%%%</div><div class=""><br class=""></div><div class="">cheers</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">/Francesco</div><div class=""><br class=""></div><div class=""><div apple-content-edited="true" class="">
<div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">-------------------------------------------</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Francesco Taddia</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Postdoctoral Researcher</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Department of Astronomy</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Stockholm University, Sweden</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy"><a href="mailto:ftadd@astro.su.se" class="">ftadd@astro.su.se</a></font></div></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"><br class="Apple-interchange-newline">
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