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Dear all,<br>
<br>
The next SU astronomy departmental seminar will take place on Friday
March 22 at 10:30am in room FC61 (AlbaNova building, 6th floor) and
on zoom
(<a class="moz-txt-link-freetext" href="https://stockholmuniversity.zoom.us/j/62211269644?pwd=K0J2eVVMa3pTa1JVN2lyRUJPR3Rjdz09">https://stockholmuniversity.zoom.us/j/62211269644?pwd=K0J2eVVMa3pTa1JVN2lyRUJPR3Rjdz09</a>).<br>
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<br>
Speaker: Khaled Al Moulla (University of Geneva)<br>
Title: Roadblocks to Detect Earth-like Exoplanets: Solar-type
Activity in Radial Velocities<br>
Event: <a class="moz-txt-link-freetext" href="https://indico.fysik.su.se/e/khaled_al_moulla">https://indico.fysik.su.se/e/khaled_al_moulla</a><br>
<br>
Abstract:<br>
The radial velocity (RV) technique for detecting exoplanets has in
recent years been limited in its applicability to search for
Earth-mass planets due to their small semi-amplitudes relative to
the intrinsic variability of their host stars. In this talk, I will
present the signatures of stellar activity in high-resolution
optical and near-infrared (NIR) spectral time series of the Sun and
solar-type stars, observed with the HARPS, HARPS-N and NIRPS
spectrographs. I will talk about a novel, physically motivated
method of RV extraction based on the average formation temperature
of spectral segments, in order to demonstrate the differential
effect of stellar activity signals as a function of photospheric
depth, enabling the separation of temperature-dependent stellar
activity from constant Keplerian signals. Additionally, I compare
the chromaticity of unsigned magnetic field proxies in the optical
versus NIR to evaluate their usefulness as activity indicators with
which the stellar signals can be mitigated.<br>
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We look forward to seeing many of you there. Thanks!<br>
<br>
Adur, Adélaïde, and Sanja<br>
<br>
Upcoming Events:<br>
<br>
2024-03-29 ** No seminar ** Good Friday<br>
2024-04-05 Simon Ringqvist<br>
2024-04-10 Yutong He (**Seminar on WEDNESDAY**)<br>
2024-04-12 Alex Riley<br>
2024-04-19 Arthur Choplin<br>
2024-04-26 Dominique Petit<br>
2024-05-03 Gang Li<br>
2024-05-08 Ivo (**Seminar on WEDNESDAY**)<br>
<br>
<br>
You can subscribe to the seminars calendar in:<br>
<a class="moz-txt-link-freetext" href="https://ttt.astro.su.se/ical/astro-seminars.ics">https://ttt.astro.su.se/ical/astro-seminars.ics</a><br>
(Please note that calendar can be subject to updates)<br>
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<br>
Join Zoom Meeting:<br>
<a class="moz-txt-link-freetext" href="https://stockholmuniversity.zoom.us/j/62211269644?pwd=K0J2eVVMa3pTa1JVN2lyRUJPR3Rjdz09">https://stockholmuniversity.zoom.us/j/62211269644?pwd=K0J2eVVMa3pTa1JVN2lyRUJPR3Rjdz09</a><br>
Meeting ID: 622 1126 9644 <font size="2"><span
style="font-size:10pt;"><br>
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