[Astronomy seminar] Astronomy departmental seminar Friday March 22 at 10:30am - Khaled Al Moulla (University of Geneva)

[Astronomy seminar announcements]

Dear all,

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 
(https://stockholmuniversity.zoom.us/j/62211269644?pwd=K0J2eVVMa3pTa1JVN2lyRUJPR3Rjdz09).
___________________

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)
___________________

Join Zoom Meeting:
https://stockholmuniversity.zoom.us/j/62211269644?pwd=K0J2eVVMa3pTa1JVN2lyRUJPR3Rjdz09
Meeting ID: 622 1126 9644
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