813 Santa Barbara St
Pasadena, CA-91101, USA
My name is Ylva Götberg and I am a postdoctoral fellow at the Carnegie Observatories located in Pasadena, California.
I am interested in binary stellar evolution and the effect of binary interactions on surrounding environments, both nearby and at high redshift.
Mainly, I use the codes MESA and CMFGEN to model the evolution and spectra of binary stars. So far, my focus has been on stars that lose their hydrogen-rich envelopes through mass transfer with a companion star.
With my PhD thesis entitled "The properties and impact of stars stripped in binaries", I graduated the 7 of February 2019 at the University of Amsterdam, Anton Pannekoek Institute for Astronomy.
The photo shows when I receive the diploma from the committee member prof. Alex de Koter. Next to him, my supervisor Dr. Selma de Mink and promotor prof. Michiel van der Klis.My thesis online
Highlights of my recent and ongoing research
We create the first grids of spectral models for stripped stars over a large range of mass. These show a smooth sequence bridging subdwarfs with Wolf-Rayet stars.
The WN3/O3 stars in the LMC show indications of being stars stripped in binaries.
We present the first spectral models made particularly for intermediate mass stars that are stripped in binaries, covering a range of metallicities.
Models in Smith et al. 2018:
These models are for stars stripped in binaries with the metallicity Z = 0.004 and that are expected to show both absorption and emission features.
Recorded outreach presentations:
Astronomy on Tap, Santa Barbara, 2017
Astronomy on Tap, Leiden, 2017
My amateur artist's impressions:
Cartoon visualizing stable mass transfer in a binary system. Download here.
The most massive star in the system evolves faster and starts to swell up when hydrogen is depleted in the center and ignited in a shell around the core (the star enters the Hertzsprung gap phase). At some point during this phase, the star is large enough for the outer layers of the star to feel a stronger gravitational force towards the companion star than to itself. This is when mass transfer starts and gaseous material starts flowing to the companion star. The companion starts accreting the transferred material, but is also spun up by the process. When most of the envelope of the donor star is lost, the hot and compact helium-rich core of the star is visible. This stripped star is blue and happy in the video.
(This video was created by Ylva Götberg for the program "BinCosmos", PI: de Mink.)
Homemade, not fully realistic artist's impressions of binary stars. (Created by Ylva Götberg)