Search Publications
Distances and ages from isochrone fits of 150 open clusters using Gaia DR2 data
Dias, W. S.; Monteiro, H.
We investigate a sample of open cluster candidates with no previous age determination using astrometric and photometric data from the Gaia DR2 catalogue. Using proper motions and parallaxes and the full co-variance matrix we determined the astrometric membership probability of the stars in the field of each candidate. The memberships were used as …
AGN feedback and multiphase gas in giant elliptical galaxies
Ruszkowski, Mateusz; Li, Yuan; Wang, Chaoran
Recent observations have found extended multiphase gas in a significant fraction of massive elliptical galaxies. We perform high-resolution three-dimensional hydrodynamical simulations of two idealized elliptical galaxies - one representing a typical galaxy characterized by initial conditions conducive to the development of thermal instability and…
Evidence for spots on hot stars suggests major revision of stellar physics
Balona, L. A.
It has long been thought that starspots are not present in the A and B stars because magnetic fields cannot be generated in stars with radiative envelopes. Space observations show that a considerable fraction of these stars varies in light with periods consistent with the expected rotation periods. Here we show that the photometric periods are the…
High-velocity outflows in massive post-starburst galaxies at z > 1
Castellano, Marco; Koekemoer, Anton M.; Pentericci, Laura +21 more
We investigate the prevalence of galactic-scale outflows in post-starburst (PSB) galaxies at high redshift (1 < z < 1.4), using the deep optical spectra available in the UKIDSS Ultra Deep Survey (UDS). We use a sample of ∼40 spectroscopically confirmed PSBs, recently identified in the UDS field, and perform a stacking analysis in order to an…
The COMBS survey - I. Chemical origins of metal-poor stars in the Galactic bulge
Kobayashi, Chiaki; Marino, Anna F.; Hawkins, Keith +7 more
Chemistry and kinematic studies can determine the origins of stellar population across the Milky Way. The metallicity distribution function of the bulge indicates that it comprises multiple populations, the more metal-poor end of which is particularly poorly understood. It is currently unknown if metal-poor bulge stars ([Fe/H] <-1 dex) are part…
Formation of globular cluster systems - II. Impact of the cut-off of the cluster initial mass function
Gnedin, Oleg Y.; Choksi, Nick
Observations of young star clusters reveal that the high-mass end of the cluster initial mass function (CIMF) deviates from a pure power law and instead truncates exponentially. We investigate the effects of this truncation on the formation of globular cluster (GC) systems by updating our analytic model for cluster formation and evolution, which i…
The scattered disc of HR 8799
Booth, Mark; Krivov, Alexander V.; Löhne, Torsten +1 more
HR 8799 is a young F0-type star with four directly imaged giant planets and two debris belts, one located exterior and another one interior to the region occupied by the planetary orbits. Not only having an architecture similar to that of our Solar system but also revealing dissimilarities such as high masses of planets, a huge radial extent, and …
Gas velocity structure of the Orion A integral-shaped filament
Stutz, Amelia M.; González Lobos, Vale
We present analysis of the gas kinematics of the integral-shaped filament (ISF) in Orion A using four different molecular lines, 12CO (1-0), 13CO (1-0), NH3 (1,1), and N2H+ (1-0). We describe our method to visualize the position-velocity (PV) structure using the intensity-weighted line velocit…
Star-forming clumps in the Lyman Alpha Reference Sample of galaxies - I. Photometric analysis and clumpiness
Hayes, Matthew; Östlin, Göran; Melinder, Jens +4 more
We study young star-forming clumps on physical scales of 10-500 pc in the Lyman-Alpha Reference Sample (LARS), a collection of low-redshift (z = 0.03-0.2) UV-selected star-forming galaxies. In each of the 14 galaxies of the sample, we detect clumps for which we derive sizes and magnitudes in five UV-optical filters. The final sample includes ∼1400…
Mean density inversions for red giants and red clump stars
Reese, D. R.; Eggenberger, P.; Bossini, D. +8 more
Since the CoRoT and Kepler missions, the availability of high-quality seismic spectra for red giants has made them the standard clocks and rulers for Galactic Archeology. With the expected excellent data from the TESS and PLATO missions, red giants will again play a key role in Galactic studies and stellar physics, thanks to the precise masses and…