<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=""><div class="">Dear all,</div><div class=""><br class=""></div><div class="">join us again on Astro Journal Club this Wednesday (Dec 20th) at 3 p.m. (sharp) in the seminar room F-201 of the Physics Department.</div><div class=""><br class=""></div><div class=""><b class="">Presenter</b>: Dina Durmić</div><div class=""><br class=""></div><div class=""><b class="">Title of paper</b>: Prospects for detection of hypervelocity stars with Gaia</div><div class=""><br class=""></div><div class=""><b class="">Authors</b>: Marchetti et al. (2017)</div><div class=""><br class=""></div><div class=""><b class="">Abstract</b>: </div><div class="">Hypervelocity stars (HVSs) are amongst the fastest object in our Milky Way. These stars are predicted to come from the Galactic center (GC) and travel along unbound orbits across the whole Galaxy. In the following years, the ESA satellite Gaia will provide the most complete and accurate catalogue of the Milky Way, with full astrometric parameters (position, parallax, and proper motions) for more than 1 billion stars. In this paper, we present the expected sample size and properties (mass, magnitude, spatial, velocity distributions) of HVSs in the Gaia stellar catalogue. We build three Gaia mock catalogues of HVSs anchored to current observations, each one exploring different assumptions on the ejection mechanism and the stellar population in the GC. In all cases, we find numbers ranging from several hundreds to several thousands. The mass distribution of observable HVSs peaks at ~1 M⊙ for stars with a relative error in total proper motion below 10%, and will therefore probe a different mass range compared to the few observed HVS candidates discovered in the past. In particular, we show that a few hundreds to a few thousands of HVSs will be bright enough to have a precise measurement of the three-dimensional velocity from Gaia alone. Finally, we also show that Gaia will provide more precise proper motion measurements for the current sample of HVS candidates. This will help identifying their birthplace narrowing down their ejection location, and confirming or rejecting their nature as HVSs. Overall, our forecasts are extremely encouraging in terms of quantity and quality of HVS data that can be potentially exploited to constrain both the Milky Way potential and the GC properties. </div><div class=""><br class=""></div><div class=""><b class="">Link to paper</b>: <a href="https://arxiv.org/abs/1711.11397" class="">https://arxiv.org/abs/1711.11397</a></div><div class=""><br class=""></div><div class="">If you’d like to present a paper from the field of astrophysics, please contact me via this email (<a href="mailto:lceraj@phy.hr" class="">lceraj@phy.hr</a>).</div><div class=""><br class=""></div><div class="">You can find information about upcoming AJC seminars and links to previous AJC presentations @ <a href="https://lanaceraj.wixsite.com/ajc-main" class="">https://lanaceraj.wixsite.com/ajc-main</a> </div><div class=""><br class=""></div><div class="">See you all on Wednesday.</div><div class=""><br class=""></div><div class="">Cheers,</div><div class="">Lana</div></body></html>