Gesa H.-M. Bertrang


Personal Details

I investigate the underlying physics by combining theory and observations!

I am an astronomer and currently Postdoctoral Researcher at Max Planck Institute for Astronomy, Heidelberg, Germany.
I am interested in polarimetry as a powerful tool to probe protoplanetary disks and low-mass star-forming regions. In my free time, I am exploring the vast beauty of South Germany.
On the following pages, I prepared an overview for you about myself and my research. Enjoy!


Aiming at understanding the formation of planets and low-mass stars, with a focus on the role of magnetic fields, I apply 3D radiative transfer simulations to combine theory and observations. My work is carried out in the optical, near-infrared, and (sub-)millimeter wavelength ranges.


Heidelberg, Germany
bertrang (at) mpia (dot) de
astro (at) gesabertrang (dot) com
skype: gesa.bertrang


I grew up in Kiel, in northern Germany, where I later studied and earned my doctorate. I was a post-doctoral fellow at Univ. de Chile and Univ. Diego Portales in Santiago de Chile before I awarded a position as Postdoctoral Researcher at Max Planck Institute for Astronomy. I now work on Königstuhl in Heidelberg, Germany.


My academic career


march 2011 -
september 2015
Kiel University
PhD student
Advisor: Sebastian Wolf

PhD (Dr. rer. nat.) on "Observations and simulations of polarized radiation as tracer of magnetic fields in star formation"...

october 2005 -
november 2010
Kiel University
Student (Dipl.-Phys.)
Advisor: Sebastian Wolf

Diploma in physics (Dipl.-Phys.) Thesis title: "Magnetic fields in star formation"...

Work experience

June 2018 - present
Max Planck Institute for Astronomy
Postdoctoral Researcher
Advisor: Mario Flock

Grant (~324,000 USD) to carry out independent research, hosted at Max Planck Institute for Astronomy (w Mario Flock)....

march 2017 -
march 2018
Universidad de Chile
Advisor: Laura Perez

Grant (~125,000 USD) from the Chilean government to carry out independent research, hosted at Universidad de Chile (w Laura Perez)....

october 2015 -
march 2017
U de Chile & U Diego Portales
MAD Fellow
Advisors: Simon Casassus & Lucas Cieza

Grant (~112,000 USD) to carry out independent research within the Millenium ALMA Disk nucleus (MAD), hosted at Universidad de Chile (w Simon Casassus) and Universidad Diego Portales (w Lucas Cieza)....

full CV


What I do

Young stars are surrounded by disks of dust and gas. These circumstellar disks are the birthplaces of planets. Understanding the physical processes in these disk is vital for the understanding of planet formation. It has been predicted that magnetic fields are an important factor on a wide range of physical processes in protoplanetary disks, such as the migration of planet(esimals) and the mere evolution of disks. Yet, observational constraints are still pending. In the classical picture, (sub-)mm continuum polarisation is the tracer for magnetic fields in disks. Aspherical dust grains, whose thermal emission is intrinsically polarized, get aligned by the magnetic field due to radiative torques. In recent years, however, this picture has been challenged. New theoretical studies show that (sub-)mm continuum polarisation can also be created by scattering of the thermal dust emission or arise from aspherical grains which are aligned by the radiation field rather than the magnetic field. These three mechanisms trace fundamentally different physics in protoplanetary disks, yet, their polarisation predictions are not clearly distinguishable. I am applying 3D radiative transfer simulations of the polarized continuum and gas emission in combination with observations to disentangle the different mechanisms behind the measured polarization aiming at constraining magnetic fields in protoplanetary disks.

I am leading an ongoing multi-wavelength study of magnetic fields in low-mass star-forming regions, so-called Bok globules.
Magnetic fields in Bok globules are very exciting since they may be the missing mechanism in the understanding of low-mass star formation. Without this additional influence, theory overpredicts the star formation rate (SFR) by two orders of magnitude.
As planets form and grow in dusty, gaseous circumstellar disks, mutual gravitational interactions between disk and planet lead to a series of phenomena such as gaps, warps, or spiral arms. I make use of multi-wavelength observations performed with VLT/SPHERE and ALMA  in combinations with radiative transfer simulations to  test for signals of this interaction.
I am supervising the undergrad-research program of Sebastián Jorquera (U de Chile) who is working with me on magnetic fields in Bok globules. Further, I am experienced as teaching assistant of several courses on undergrad level at Kiel University (Physics IV: nuclear physics, particle physics, astrophysics and cosmology; Elementary mathematical methods in physics I & II).


Get in touch with me

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My address

skype: gesa.bertrang
phone: +49 6221 528 367

Max Planck Institute for Astronomy
Room 318
Königstuhl 17
69117 Heidelberg, Germany

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