Fredagskollokvium: Tomographic exploration of active solar/stellar atmospheres with modern mm & radio telescopes

Atul Mohan, Postdoctoral Fellow at Rosseland Centre for Solar Physics, University of Oslo.

portrettbildet av en ung mann
Atul Mohan, Postdoctor in solar physics (RoCS), University of Oslo. Photo: UiO.

Millimeter to radio waveband collectively probe the activity across the hot outer atmospheric layers of the sun and cool stars. While metrewavebands are sensitive to emission from various coronal layers, millimeter band is sensitive to thermal emission from layers across chromosphere to corona. Previous decade witnessed the dawn of sensitive interferometric arrays across mm - radio band, facilitating snaphot spectroscopic imaging studies at spectro-temporal cadence like never before.

My talk will broadly cover the research avenues and some novel insights gained using data from modern radio and mm telescopes.
In the case of the Sun, modern metrewave instruments have helped produce spatialy resolved dynamic spectra for the quiet and active solar corona at sub-second and sub-MHz resolution. Studies of radio bursts using such spatially resolved spectra have lead to new discoveries and opened up means to explore plasma turbulence in the corona. Meanwhile in mm band ALMA opened a window into high cadence solar/stellar chromospheres. Due to its supreme sensitivity and high angular resolution (~ few to sub arcsec) in this band, it is now possible to do sensitive high resolution studies of solar chromoshpere. Besides, the high sensitivity lets us explore the chromospheric structure and activity in cool stars within ~ 10 - 20 pc, letting us define novel robust indicators of solar/stellar activity.

images of the sun at different frequencies in the mm-radio band
Sun in mm - metre wavebands. Credits: SSW-KSP Team, Solar ALMA team, MWA SHI team.

This Friday colloquium will be hybrid. Attendees can therefore participate either in-person or via Zoom. Please join via Zoom at

https://uio.zoom.us/j/69001043754?pwd=cEJpbVE5ci9PdWNtRld2TDNNcGtKdz09

Meeting ID:690 0104 3754

Passcode: PeiseStua3

Attendees will be muted during the colloquium, but will have the opportunity to ask questions at the end by clicking on the "raise hand” button (or send a request via chat).

Emneord: fredagskollokvium, institute seminar, Solar Physics, Solfysikk, ALMA, Observations
Publisert 9. jan. 2023 12:38 - Sist endret 10. jan. 2023 16:57