中国科学院云南天文台特邀学术报告

YNAO Colloquium 2025

第22期

报告题目：Shock Waves, Gravity Waves, and Atmospheric Dynamics from Space and Antarctica Missions 

主讲人：Prof. Dr. Merieme Chadid

报告人单位：Université Côte d’Azur (France)

报告语言：English

报告时间：2025年11月25日（星期二）10:30-12:00

报告地点：科研7号楼2楼阶梯教室

主持人：陈雪飞

腾讯会议号：313-808-936

特别提醒：本期的学术报告时间是星期二，烦请相互转告。

报告摘要：

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I will report the first detection of gravity modes in a pulsating RR Lyrae stars, made possible by unique Antarctic ground-based observations. For several decades, such low-frequency modes, whose restoring force is buoyancy, have been actively sought in oscillating stars, yet even in the Sun their detection remains debated. In this work, I exploit the exceptional observing conditions of Antarctica with the Antarctic polar photometer PAIX, the first robotic polar multiband photometer, to obtain long, uninterrupted multi-band (UBVRI) photometry over 150 days during a single polar night on the high Antarctic plateau. These PAIX observations reveal an exceptional rich frequency spectrum with mixed pressure and gravity modes. Low-frequency, nonradial modes and their harmonics interact linearly with the dominant fundamental radial pressure mode and its second and third overtones, and half-integer frequencies and multiplet side peaks are clearly detected. Complementary space-based observations from CoRoT, Kepler, and TESS place the PAIX results in a broader astrophysical context, however, it is the continuous, high-quality Antarctic time series that enables the direct identification of gravity modes. I will discuss the excitation of internal gravity modes by penetrative convection in the extended convective envelope of RR Lyrae stars, and show that these stars are simultaneous p-mode and g-mode pulsators. This new seismic view of RR Lyrae variables, grounded in Antarctic photometry, places strong constraints on their internal structure and provides fresh insight into the long-standing Blazhko challenge and stellar evolution theory.

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报告人简介：

Prof. Dr. Merieme Chadid is an astronomer at Université Côte d’Azur (France), with broad international experience in stellar physics, observational astrophysics, and polar instrumentation. She has led pioneering work on polar robotic telescopes in Antarctica. She holds a Ph.D. in Astronomy and Space Science from Université Paul Sabatier, Toulouse, and a Habilitation (HDR) from Université Nice Sophia Antipolis. After serving as an ESO astronomer at Paranal Observatory (VLT, Chile), she joined the University of Côte d’Azur as a staff astronomer. Prof. Chadid is a consortium member of major space missions (CoRoT, Kepler, TESS, PLATO, GAIA, SVOM) and has extensive observational experience with leading facilities such as CFHT, VLT, Keck, OHP, Pic du Midi, and Las Campanas. She currently serves as President of IAU Division G (Stars and Stellar Physics) and President of the UNESCO International Scientific Board for Basic Sciences.

主办：中国科学院云南天文台学术委员会

联系人：柳正伟