A5033850791- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- History and Developments in Astronomy
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Cosmology and Gravitation Theories
- Pulsars and Gravitational Waves Research
- Spectroscopy and Laser Applications
- Astronomical and nuclear sciences
- Calibration and Measurement Techniques
- Natural Products and Biological Research
- Archaeology and ancient environmental studies
- Remote Sensing in Agriculture
- Atmospheric Ozone and Climate
- Scientific Research and Discoveries
- Historical and Architectural Studies
- Impact of Light on Environment and Health
- Plant Parasitism and Resistance
- Diversity and Career in Medicine
- Mentoring and Academic Development
University of Groningen
2011-2025
Astronomical Institute of the Slovak Academy of Sciences
2010-2025
Leibniz Institute for Astrophysics Potsdam
2014-2022
Campbell Collaboration
2019
Max Planck Institute for Astronomy
2019
Max Planck Society
2019
Union astronomique internationale
2017
Centre for Astrophysics of the University of Porto
2017
University of Potsdam
2017
University of Victoria
2012-2016
We investigate the origin of galaxy bimodality by quantifying relative role intrinsic and environmental drivers to cessation (or `quenching') star formation in over half a million local Sloan Digital Sky Survey (SDSS) galaxies. Our sample contains wide variety galaxies at z=0.02-0.2, with stellar masses 8 < log(M*/M_sun) 12, spanning entire morphological range from pure disks spheroids, four orders magnitude density halo mass. utilise published rates add this recent GIM2D photometric mass...
We present the Pristine survey, a new narrow-band photometric survey focused on metallicity-sensitive Ca H & K lines and conducted in northern hemisphere with wide-field imager MegaCam Canada-France-Hawaii Telescope (CFHT). This paper reviews our overall strategy discusses data processing metallicity calibration. Additionally we review application of these to main aims which are gather large sample most metal-poor stars Galaxy, further characterise faintest Milky Way satellites, map...
Abstract We present an atlas and follow-up spectroscopic observations of 87 thin stream-like structures detected with the STREAMFINDER algorithm in Gaia DR3, which 28 are new discoveries. Here, we focus on using these streams to refine mass models Galaxy. Fits a double-power-law halo outer power-law slope set − β h = −3 yield inner <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>−</mml:mo> <mml:msub> <mml:mi>γ</mml:mi> <mml:mi>h</mml:mi> </mml:msub>...
The NIR Ca II triplet absorption lines have proven to be an important tool for quantitative spectroscopy of individual red giant branch stars in the Local Group, providing a better understanding metallicities Milky Way and dwarf galaxies thereby opportunity constrain their chemical evolution processes. An interesting puzzle this field is significant lack extremely metal-poor stars, below [Fe/H]=-3, found classical around using technique. question arises whether these are really absent, or if...
A substantial fraction of the lowest metallicity stars show very high enhancements in carbon. It is debated whether these reflect stars' birth composition, or if their atmospheres were subsequently polluted, most likely by accretion from an asymptotic giant branch binary companion. Here we investigate and compare properties three carbon-enhanced subclasses: The metal-poor CEMP-s that are additionally enhanced barium; higher (sg)CH- Ba II also CEMP-no stars, not barium. Through comparison...
We have combined deep photometry in the B, V and I bands from CTIO/MOSAIC of Sculptor dwarf spheroidal galaxy, going down to oldest main sequence turn-offs, with spectroscopic metallicity distributions red giant branch stars. This allows us obtain most detailed complete star formation history date, as well an accurate timescale for chemical enrichment. The shows that is dominated by old (>10 Gyr), metal-poor stars, but younger, more metal-rich populations are also present. Using histories...
We present the results of a dedicated search for extremely metal-poor stars in Fornax, Sculptor, and Sextans dSphs. Five were selected from two earlier VLT/Giraffe HET/HRS surveys subsequently followed up at high spectroscopic resolution with VLT/UVES. All them turned out to have [Fe/H] ≲ −3 three are below ~ −3.5. This constitutes first evidence that classical dSphs Fornax join Sculptor containing suggests all contain stars. One giant = −3.96 ± 0.06 is most star ever observed an external...
The detailed abundances of 23 chemical elements in nine bright red giant branch stars the Carina dwarf spheroidal galaxy are presented based on high-resolution spectra gathered at Very Large Telescope (VLT) and Magellan telescopes. A spherical model atmospheres analysis is applied using standard methods (local thermodynamic equilibrium plane-parallel radiative transfer) to ranging from 380 680 nm. Stellar parameters found be consistent between photometric spectroscopic analyses, both...
We present a model for the satellites of Milky Way in which galaxy formation is followed using semi-analytic techniques applied to six high-resolution N-body simulations galactic halos Aquarius project. The model, calculated Galform code, incorporates improved treatments relevant physics LambdaCDM cosmogony, particularly self-consistent calculation reionization by UV photons emitted forming population, including progenitors central galaxy. Along merger tree each halo, calculates gas cooling...
Several challenges (e.g., sexism, parental leave, the glass ceiling, etc.) disproportionately affect women in academia (and beyond), and thus perpetuate leaky pipeline metaphor for who opt-out of an academic career. Although this pattern can be seen at all levels hierarchy, a critical time facing such is during postdoctoral stage, when personal life transitions professional ambitions collide. Using social identity approach, we explore factors affecting mental health women, including...
We present deep photometry in the B,V and I filters from CTIO/MOSAIC for about 270.000 stars Fornax dwarf Spheroidal galaxy, out to a radius of r_ell\sim0.8 degrees. By combining accurately calibrated with spectroscopic metallicity distributions individual Red Giant Branch we obtain detailed star formation chemical evolution history Fornax. is dominated by intermediate age (1-10 Gyr) stellar populations, but also includes ancient (10-14 Gyr), young (<1 stars. show that displays radial...
We quantify the impact that a variety of galactic and environmental properties have on quenching star formation. collate sample $\sim$ 400,000 central 100,000 satellite galaxies from Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Specifically, we consider velocity dispersion ($\sigma_{c}$), stellar, halo, bulge disk mass, local density, bulge-to-total ratio, group-centric distance galaxy-halo mass ratio. develop apply new statistical technique to quenched fraction ($f_{\rm Quench}$)...
We use Gaia DR2 astrometric and photometric data, published radial velocities MESA models to infer distances, orbits, surface gravities, effective temperatures for all ultra metal-poor stars ($\FeH<-4.0$ dex) available in the literature. Assuming that these are old ($>11\Gyr$) they expected belong Milky Way halo, we find 42 (18 dwarf 24 giants or sub-giants) currently within $\sim20\kpc$ of Sun map a wide variety orbits. A large fraction those remains confined inner parts halo was likely...
The Canada-France Imaging Survey (CFIS) will map the northern high Galactic latitude sky in $u$-band ("CFIS-u", 10,000$\, {\rm deg^2}$) and $r$-band ("CFIS-r", 5,000$\, deg^2}$), enabling a host of stand-alone science investigations, providing some ground-based data necessary for photometric redshift determination Euclid mission. In this first contribution we present component survey, describe observational strategy, discuss highlight results, based on approximately one third final area. We...
ABSTRACT The oldest stars in the Milky Way (born first few billion years) are expected to have a high density inner kpc, spatially overlapping with Galactic bulge. We use spectroscopic data from Pristine Inner Galaxy Survey (PIGS) study dynamical properties of ancient, metal-poor stars. compute distances using starhorse, and orbital barred potential. With this paper, we release AAT/PIGS catalogue (13 235 stars). find that most PIGS orbits typical for pressure-supported population. fraction...
We used the spectro-photometric information of ∼219 million stars from Gaia ’s Data Release 3 (DR3) to calculate synthetic, narrowband, metallicity-sensitive CaHK magnitudes that mimic observations Pristine survey, a survey photometric metallicities Milky Way has been mapping more than 6500 deg 2 northern sky with Canada–France–Hawaii Telescope since 2015. These synthetic were for an absolute recalibration deeper photometry and, combined broadband information, and estimate over whole sky....
We present a new analysis of the Aquarius simulations done in combination with semi-analytic galaxy formation model. Our goal is to establish whether subhaloes Λ cold dark matter Milky Way (MW) like systems could host dwarf spheroidal (dSph) satellites our Galaxy. shows that, contrary what has been assumed most previous work, mass profiles are generally not well fitted by Navarro–Frenk–White models but that Einasto preferred. find for shape parameters α = 0.2–0.5 and vmax 10–30 km s−1 there...
We present abundances for seven stars in the (extremely) low-metallicity tail of Sculptor dwarf spheroidal galaxy, from spectra taken with X-shooter on ESO VLT. Targets were selected Ca II triplet (CaT) survey Dwarf Abundances and Radial Velocities Team (DART) using latest calibration. Of extremely metal-poor candidates, five are confirmed to be (i.e., [Fe/H]<-3 dex), [Fe/H]=-3.47 +/- 0.07 our most star. All around or below [Fe/H]=-2.5 dex measurement individual Fe lines. These values...
Building on our previous spectroscopic and photometric analysis of the isolated Local Group dwarf irregular (dIrr) galaxy WLM, we present a comparison metallicities its RGB stars with respect to well studied spheroidal galaxies (dSphs) Magellanic Clouds. We calculate mean metallicity [Fe/H]$ = -1.28 \pm 0.02$, intrinsic spread in $\sigma 0.38 0.04$ dex, similar observed massive dSph Fornax Small Cloud. Thus, despite environment global still follows expectations for WLM's mass chemical...
The ages of individual Red Giant Branch stars (RGB) can range from 1 Gyr old to the age Universe, and it is believed that abundances most chemical elements in their photospheres remain unchanged with time (those are not affected by 1st dredge-up). This means they trace ISM galaxy at star formed, hence enrichment history galaxy. CMD analysis has shown Carina dwarf spheroidal (dSph) have had an unusually episodic formation (SFH) which expected be reflected different elements. We use VLT-FLAMES...
Fornax is one of the most massive dwarf spheroidal galaxies in Local Group. The field star population dominated by intermediate age stars but formation was going on over almost its entire history. It has been proposed that experienced a minor merger event. Despite recent progress, only high metallicity end ([Fe/H]>-1.2 dex) sampled larger number via resolution spectroscopy. We want to better understand full chemical evolution this galaxy sampling whole range, including more metal poor stars....