My main research interest is feedback from massive stars, and the key question I am trying to answer is: how exactly do massive stars influence their environment?
We know that massive stars have an enourmous impact on their sourroundings throughout their lifetime via jets/outflows, powerful winds, strong ionising radiation, and ultimately by exploding as supernovae. We can quantify these various feedback mechanisms by simulating one or more at a time, but observationally, the quantification of massive star formation feedback is very challenging.
To observationally quantify feedback from massive stars I use data from so-called integral field spectrographs like MUSE or KMOS on the Very Large Telescope in Chile . With this data, I identify and classify the feedback-driving massive stars while simultaneously linking them to the properties and kinematics of the feedback-driven gas.
I am also a strong advocate for early-career mothers in STEM fields, as well as researchers with unusual paths to astronomy and academia. My wishes for the future: free child care at all major conferences, travel allowances for mothers traveling to conferences with their small (dependant) kids, as well as child care supprt for PhD students and postdocs.
Abstract (see article for citations): The physics of star formation and the deposition of mass, momentum and energy into the interstellar medium by massive stars (‘feedback’) are the main uncertainties in modern cosmological simulations of galaxy formation and evolution. These processes determine the properties of galaxies but are poorly understood on the scale of individual giant molecular clouds (less than 100 parsecs), which are resolved in modern galaxy formation simulations. The key question is why the timescale for depleting molecular gas through star formation in galaxies (about 2 billion years) exceeds the cloud dynamical timescale by two orders of magnitude. Either most of a cloud’s mass is converted into stars over many dynamical times or only a small fraction turns into stars before the cloud is dispersed on a dynamical timescale. Here we report high-angular-resolution observations of the nearby flocculent spiral galaxy NGC 300. We find that the molecular gas and high-mass star formation on the scale of giant molecular clouds are spatially decorrelated, in contrast to their tight correlation on galactic scales. We demonstrate that this decorrelation implies rapid evolutionary cycling between clouds, star formation and feedback. We apply a statistical method to quantify the evolutionary timeline and find that star formation is regulated by efficient stellar feedback, which drives cloud dispersal on short timescales (around 1.5 million years). The rapid feedback arises from radiation and stellar winds, before supernova explosions can occur. This feedback limits cloud lifetimes to about one dynamical timescale (about 10 million years), with integrated star formation efficiencies of only 2 to 3 per cent. Our findings reveal that galaxies consist of building blocks undergoing vigorous, feedback-driven life cycles that vary with the galactic environment and collectively define how galaxies form stars.
We recently reported the discovery of a candidate jet-driving microquasar (S10) in the nearby spiral galaxy NGC 300. However, in the absence of kinematic information, we could not reliably determine the jet power or the dynamical age of the jet cavity. Here, we present optical MUSE integral field unit (IFU) observations of S10, which reveal a bipolar line-emitting jet structure surrounding a continuum-emitting central source. The optical jet lobes of S10 have a total extent of ∼ 40 pc and a shock velocity of ∼ 150 km s-1. Together with the jet kinematics, we exploit the MUSE coverage of the Balmer Hβ line to estimate the density of the surrounding matter and therefore compute the jet power to be Pjet ≈ 6.3 × 1038 erg s-1. An optical analysis of a microquasar jet bubble and a consequent robust derivation of the jet power have been possible only in a handful of similar sources. This study therefore adds valuable insight into microquasar jets, and demonstrates the power of optical integral field spectroscopy in identifying and analysing these objects.
We use MUSE data from the Very Large Telescope in Chile to analyse the effect of feedback from massive stars in the low-metallicity environment of the Large Magellanic Cloud.
For 11 HII regions in total, we identify and classify the feedback-driving stars and analyse their feedback effect in terms of energy and momentum input into the surrounding matter by linking them the feedback-affected gas in the HII regions.
We analyse the role of different stellar feedback mechanisms for each region by measuring the direct radiation pressure, the pressure of the ionised gas, and the pressure of the shock-heated winds. We find the expansion of the HII regiosn is mainly diven by stellar winds and ionised gas, while the pressure imparted by the stellar radiation is up to three orders of magnitude lower than the other pressure terms. We relate the total pressure to the star formation rate and find that stellar feedback has a negative effect on star formation, and sets an upper limit to the rate at which stars are formes as a function of increasing pressure.