NGTS
NGTS is a collection of small telescopes on the Atacama desert which runs a slew of observation programmes. In particular we looks for eclipsing stars and planets in young stellar clusters.
Hej! I am Louise and I search for young exoplanets
I am an astronomer searching for planets around other stars than our Sun, called exoplanets. I determine their mass and radius to understand their interior and what they are made of. I am especially interested in young planets and their active host stars.
I am a staff astronomer at the Universitäts-Sternwarte München, which is part of LMU Munich. I work on characterising planets orbiting young, active stars.
I obtained my PhD degree in 2021 from Geneva University. As a PhD candidate, I worked on radial velocity follow-up of transiting exoplanets with the spectrographs HARPS and CORALIE. Planets transiting bright stars give us unique opportunities to fully characterise planetary systems. We can determine both the planatary mass and radius and investigate the atmosphere through transmission spectroscopy.
After my PhD I worked as a Swiss National Science Foundation postdoctoral fellow at Oxford University and as an ESO research fellow in Garching by Munich. In my current research, I focus on planets transiting young stars that are highly active and thus tricky to characterise robustly. I develop methods that will allow us to mitigate and model stellar activity signals, with a focus on using simultaneous visible and near infra-red high resolution spectroscopy.
I am originally from Denmark, where I studied physics at the Niels Bohr Institute in Copenhagen. While finishing my Master's degree, I worked as a student support astronomer at the Nordic Optical Telescope in La Palma, Spain. I have also worked at Gemini North on reducing spectra of high redshift galaxies from the Hubble space telescope and as a young graduate trainee at ESA in the Netherlands simulating transmission spectroscopy with NIRspec/JWST.
Exoplanet research
I have a wide range of research interests from transit surveys to internal structure modelling of giant planets
Radial velocity measurements
Working mainly with HARPS on the 3.6m ESO telescope and CORALIE on the Swiss 1.2m Euler telescope I follow-up planet transiting planet candidates. I am looking forward to expanding our wavelength coverage with the near-infrared high resolution spectrograph NIRPS which will join HARPS in 2021.
Transition between Neptune- and Saturn-like planets
If a giant planet turns out as a Neptune-like ice giant of a Saturn-like gas giant is believed to be determined by a stage of planet formation called runaway gas accretion. Characterising these types of planets in detail is key to our understanding of planet formation.
Publications
My first author publications are listed below. The full list of my 70+ peer reviewed publications can be found at ORCID, Google Scholar and the ADS.
Three Short Period Jupiters from TESS
Nielsen et al. A&A 639, A76 (2020)
Discovery paper for HIP 65Ab, TOI-157 and TOI-169; three Jupiter-like planets all with unusually short orbital periods of less than 2.5 days. Of special note is HIP 65Ab (TOI-129b) which is a 3.2 Mjup planet in a 0.98 day orbit around a K-star which in return is part of a visual binary. The transit is grazing so we do not have a good radius estimate. More encouragingly, we do have a beautiful phase curve based on the TESS data.
Mass determinations of the three mini-Neptunes transiting TOI-125
Nielsen et al. MNRAS 492, 5399– (2020)
TOI-125 is a bright star which hosts three mini-Neptues close to mean motion resonance. The planets were discovered by TESS and initially published by Quinn et al. 2019. Subsequently as part of a large collaboration we follwed it up with HARPS to get precise masses of the planets.
Three hot Jupiters and one bloated sub-Saturn mass planet discovered by WASP-South
Nielsen et al. MNRAS 489, 2478– (2019)
WASP-169b, WASP-171b, WASP-175b, and WASP-182b: Four new WASP planets of which one of them, WASP-182b, is a bloated sub-Saturn mass planet around a bright metal-rich star. With an orbital period of P = 3.377 d, it sits right in the apex of the sub-Jovian desert, bordering the upper and lower edge of the desert in both the mass–period and radius–period plane. WASP-169b, WASP-175b, and WASP-182b are promising targets for atmospheric characterization through transmission spectroscopy, with expected transmission signals of 121, 150, and 264 ppm, respectively.
A Jovian planet in an eccentric 11.5 day orbit around HD 1397 discovered by TESS
Nielsen et al. A&A 623, A100 (2019)
HD 1397b (TOI-120) was one of the first confirmed TESS planets. It is a giant planet in an 11.5 day eccentric orbit around a bright (V = 7.9) G-type subgiant.