Search Publications
Strong lensing constraints on primordial black holes as a dark matter candidate
Treu, Tommaso; Gilman, Daniel; Dike, Veronica
Dark matter could comprise, at least in part, primordial black holes (PBHs). To test this hypothesis, we present an approach to constrain the PBH mass (MPBH) and mass fraction (fPBH) from the flux ratios of quadruply imaged quasars. Our approach uses an approximate Bayesian computation forward modelling technique to directly …
Sub-m s-1 upper limits from a deep HARPS-N radial-velocity search for planets orbiting HD 166620 and HD 144579
Vanderburg, A.; Poretti, E.; Sozzetti, A. +20 more
Minimizing the impact of stellar variability in radial velocity (RV) measurements is a critical challenge in achieving the 10 cm s-1 precision needed to hunt for Earth twins. Since 2012, a dedicated programme has been underway with HARPS-N, to conduct a blind RV rocky planets search (RPS) around bright stars in the Northern hemisphere. …
Fraction of stars in clusters for the LEGUS dwarf galaxies
Östlin, G.; Cignoni, M.; Tosi, M. +20 more
We study the young star cluster populations in 23 dwarf and irregular galaxies observed by the Hubble Space Telescope (HST) Legacy ExtraGalactic Ultraviolet Survey (LEGUS), and examine relationships between the ensemble properties of the cluster populations and those of their host galaxies: star formation rate (SFR) density (ΣSFR). A st…
Modelling continuum reverberation in active galactic nuclei: a spectral-timing analysis of the ultraviolet variability through X-ray reverberation in Fairall 9
Done, Chris; Hagen, Scott
Continuum reverberation mapping of active galactic nuclei (AGNs) can provide new insight into the nature and geometry of the accretion flow. Some of the X-rays from the central corona irradiating the disc are absorbed, increasing the local disc temperature. This gives an additional reprocessed contribution to the spectral energy distribution (SED)…
Monitoring the young planet host V1298 Tau with SPIRou: planetary system and evolving large-scale magnetic field
Moutou, C.; Carmona, A.; Donati, J. -F. +15 more
We report results of a spectropolarimetric monitoring of the young Sun-like star V1298 Tau based on data collected with the near-infrared spectropolarimeter SPIRou at the Canada-France-Hawaii Telescope between late 2019 and early 2023. Using Zeeman-Doppler Imaging and the Time-dependent Imaging of Magnetic Stars methods on circularly polarized spe…
Line luminosities of Galactic and Magellanic Cloud Wolf-Rayet stars
Crowther, Paul A.; Bestenlehner, Joachim M.; Rate, G.
We provide line luminosities and spectroscopic templates of prominent optical emission lines of 133 Galactic Wolf-Rayet (WR) stars by exploiting Gaia DR3 parallaxes and optical spectrophotometry, and provide comparisons with 112 counterparts in the Magellanic Clouds. Average line luminosities of the broad blue (He II λ4686, C III λλ4647,51, N III …
A spectral classification system for hydrogen-deficient carbon stars
Ruiter, Ashley J.; Clayton, Geoffrey C.; García-Hernández, D. A. +6 more
Stellar spectral classification has been highly useful in the study of stars. While there is a currently accepted spectral classification system for carbon stars, the subset of hydrogen-deficient carbon (HdC) stars has not been well described by such a system, due predominantly to their rarity and their variability. Here we present the first syste…
Dynamical age of the Tucana-Horologium young stellar association
Bouy, Hervé; Barrado, David; Galli, Phillip A. B. +2 more
The Tucana-Horologium association is one of the closest young stellar groups to the Sun and despite the close proximity its age is still debated in the literature. We take advantage of the state-of-the-art astrometry delivered by the third data release of the Gaia space mission combined with precise radial velocity measurements obtained from high-…
The membership of stars, density profile, and mass segregation in open clusters using a new machine learning-based method
Noormohammadi, M.; Khakian Ghomi, M.; Haghi, H.
A combination of two unsupervised machine learning algorithms, DBSCAN: Density-Based Spatial Clustering of Applications with Noise, and GMM: Gaussian mixture models, are used to find members with a high probability of 12 open clusters, M38, NGC2099, Coma Ber, NGC752, M67, NGC2243, Alessi01, Bochum04, M34, M35, M41, and M48, based on Gaia DR3. Thes…
An M dwarf accompanied by a close-in giant orbiter with SPECULOOS
Triaud, Amaury H. M. J.; Tamura, Motohide; Hirano, Teruyuki +40 more
In the last decade, a dozen close-in giant planets have been discovered orbiting stars with spectral types ranging from M0 to M4, a mystery since known formation pathways do not predict the existence of such systems. Here, we confirm TOI-4860 b, a Jupiter-sized planet orbiting an M4.5 host, a star at the transition between fully and partially conv…