[Astronomy seminar] Reminder: Astronomy departmental seminar - Khaled Al Moulla

[Astronomy seminar announcements]

Dear all,

This is a reminder for the departmental seminar today at 10:30am in room FC61 (AlbaNova building, 6th floor) and on zoom (https://stockholmuniversity.zoom.us/j/62211269644?pwd=K0J2eVVMa3pTa1JVN2lyRUJPR3Rjdz09).
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Speaker: Khaled Al Moulla (University of Geneva)
Title: Roadblocks to Detect Earth-like Exoplanets: Solar-type Activity in Radial Velocities
Event: https://indico.fysik.su.se/e/khaled_al_moulla

Abstract:
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.
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We look forward to seeing many of you there. Thanks!

Adur, Adélaïde, and Sanja

Upcoming Events:

2024-03-29 ** No seminar ** Good Friday
2024-04-05 Simon Ringqvist
2024-04-10 Yutong He (**Seminar on WEDNESDAY**)
2024-04-12 Alex Riley
2024-04-19 Arthur Choplin
2024-04-26 Dominique Petit
2024-05-03 Gang Li
2024-05-08 Ivo (**Seminar on WEDNESDAY**)


You can subscribe to the seminars calendar in:
https://ttt.astro.su.se/ical/astro-seminars.ics
(Please note that calendar can be subject to updates)
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Join Zoom Meeting:
https://stockholmuniversity.zoom.us/j/62211269644?pwd=K0J2eVVMa3pTa1JVN2lyRUJPR3Rjdz09
Meeting ID: 622 1126 9644
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