Search Publications
K2 results for "young" α-rich stars in the Galaxy
Valentini, M.; Chiappini, C.; Tailo, M. +11 more
Context. The origin of apparently young α-rich stars in the Galaxy is still a matter of debate in Galactic archaeology, whether they are genuinely young or might be products of binary evolution, and mergers or mass accretion.
Aims: Our aim is to shed light on the nature of young α-rich stars in the Milky Way by studying their distribution in …
MINDS: The DR Tau disk: II. Probing the hot and cold H2O reservoirs in the JWST-MIRI spectrum
Henning, Thomas; Güdel, Manuel; Tabone, Benoît +14 more
Context. The Medium Resolution Spectrometer (MRS) of the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) gives insights into the chemical richness and complexity of the inner regions of planet-forming disks. Several disks that are compact in the millimetre dust emission have been found by Spitzer to be particularly bright i…
An absence of binary companions to Wolf-Rayet stars in the Small Magellanic Cloud: Implications for mass loss and black hole masses at low metallicities
Wang, C.; Shenar, T.; Sana, H. +6 more
To predict black hole mass distributions at high redshifts, we need to understand whether very massive single stars (M ≳ 40 M⊙) with low metallicities (Z) lose their hydrogen-rich envelopes, like their metal-rich counterparts, or whether a binary companion is required to achieve this. To test this, we undertook a deep spectroscopic sear…
Witnessing an extreme, highly efficient galaxy formation mode with resolved Lyman-α and Lyman-continuum emission
Chisholm, J.; Schaerer, D.; Marques-Chaves, R. +9 more
J1316+2614 at z = 3.613 is the UV-brightest (MUV = ‑24.7) and strongest Lyman continuum-emitting (fescLyC ≈ 90%) star-forming galaxy known; it also shows signatures of inflowing gas from its blue-dominated Lyα profile. We present high-resolution imaging with the Hubble Space Telescope (HST) and the Very Large Teles…
IXPE observation of PKS 2155–304 reveals the most highly polarized blazar
Kaaret, Philip; Wu, Kinwah; Enoto, Teruaki +133 more
We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155‑304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also conducted an extensive contemporaneous multiwavelength (MW) campaign. We find that during the first half (T
CHEX-MATE: Robust reconstruction of temperature profiles in galaxy clusters with XMM-Newton
Arnaud, M.; Pointecouteau, E.; Pratt, G. W. +25 more
The "Cluster HEritage project with XMM-Newton: Mass Assembly and Thermodynamics at the End point of structure formation" (CHEX-MATE) is a multi-year heritage program to obtain homogeneous XMM-Newton observations of a representative sample of 118 galaxy clusters. The observations are tuned to reconstruct the distribution of the main thermodynamic q…
Complex angular structure of three elliptical galaxies from high-resolution ALMA observations of strong gravitational lenses
Vegetti, S.; McKean, J. P.; Fassnacht, C. D. +4 more
The large-scale mass distributions of galaxy-scale strong lenses have long been assumed to be well described by a singular ellipsoidal power-law density profile with external shear. However, the inflexibility of this model could lead to systematic errors in astrophysical parameters inferred with gravitational lensing observables. Here, we present …
Consistency of JWST black hole observations with NANOGrav gravitational wave measurements
Hütsi, Gert; Ellis, John; Fairbairn, Malcolm +3 more
JWST observations have opened a new chapter in supermassive black hole (SMBH) studies, stimulating discussion of two puzzles: the abundance of high-z SMBHs and the fraction of dual active galactic nuclei (AGNs). We argue that the answers to these puzzles may be linked to an interpretation of the data on the nanohertz gravitational waves (GWs) disc…
Clumpy star formation and an obscured nuclear starburst in the luminous dusty z = 4 galaxy GN20 seen by MIRI/JWST
Östlin, G.; Güdel, M.; Colina, L. +28 more
Dusty star-forming galaxies emit most of their light at far-infrared to millimeter wavelengths as their star formation is highly obscured. Far-infrared and millimeter observations have revealed their dust, neutral and molecular gas properties. The sensitivity of JWST at rest-frame optical and near-infrared wavelengths now allows the study of the s…
Abundances of iron-peak elements in accreted and in situ born Galactic halo stars
Skúladóttir, Á.; Amarsi, A. M.; Nissen, P. E. +1 more
Context. Studies of the element abundances and kinematics of stars belonging to the Galactic halo have revealed the existence of two distinct populations: accreted stars with a low [α/Fe] ratio and in situ born stars with a higher ratio.
Aims: Previous work on the abundances of C, O, Na, Mg, Si, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in high-α an…