Search Publications
Raising the observed metallicity floor with a 3D non-LTE analysis of SDSS J102915.14+172927.9
Hansen, T. T.; Amarsi, A. M.; Lind, K. +4 more
Context. The first stars marked the end of the cosmic dark ages, produced the first heavy elements, and set the stage for the formation of the first galaxies. Accurate chemical abundances of ultra metal-poor stars ([Fe/H] < −4) can be used to infer the properties of the first stars and thus the formation mechanism for low-mass second-generation…
Relation between metallicities and spectral energy distributions of Herbig Ae/Be stars. A potential link with planet formation
Montesinos, B.; Mendigutía, I.; Kama, M. +5 more
Context. Most studies devoted to Herbig Ae/Be stars (HAeBes) assume solar metallicity. However, the stellar metallicity, [M/H], is a fundamental parameter that can strongly differ depending on the source and may have important implications for planet formation. It has been proposed that the deficit of refractory elements observed in the surfaces o…
Matter ejections behind the highs and lows of the transitional millisecond pulsar PSR J1023+0038
Covino, S.; D'Avanzo, P.; Campana, S. +23 more
Transitional millisecond pulsars are an emerging class of sources that link low-mass X-ray binaries to millisecond radio pulsars in binary systems. These pulsars alternate between a radio pulsar state and an active low-luminosity X-ray disc state. During the active state, these sources exhibit two distinct emission modes (high and low) that altern…
A compact multi-planet system transiting HIP 29442 (TOI-469) discovered by TESS and ESPRESSO. Radial velocities lead to the detection of transits with low signal-to-noise ratio
Bouchy, F.; Rebolo, R.; Zapatero Osorio, M. R. +52 more
Context. One of the goals of the Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) Guaranteed Time Observations (GTO) consortium is the precise characterisation of a selected sample of planetary systems discovered by TESS. One such target is the K0V star HIP 29442 (TOI-469), already known to host a validate…
The ALMA Frontier Fields Survey. VI. Lensing-corrected 1.1 mm number counts in Abell 2744, MACSJ0416.1-2403, MACSJ1149.5+2223, Abell 370, and Abell S1063
Kneissl, R.; Demarco, R.; Bauer, F. E. +8 more
Context. Probing the faint end of the number counts at millimeter wavelengths is important in order to identify the origin of the extragalactic background light in this regime. Aided by strong gravitational lensing, ALMA observations toward massive galaxy clusters have opened a window to probe this origin, allowing us to resolve sub-milliJansky du…
Searching for Milky Way twins: Radial abundance distribution as a strict criterion
Tautvaišienė, G.; Lara-López, M. A.; Pilyugin, L. S.
We search for Milky Way-like galaxies among a sample of approximately 500 galaxies. The characteristics we considered of the candidate galaxies are the following: stellar mass M⋆, optical radius R25, rotation velocity Vrot, central oxygen abundance (O/H)0, and abundance at the optical radius (O/H)R<…
The metallicity distribution in the core of the Sagittarius dwarf spheroidal: Minimising the metallicity biases
Dalessandro, Emanuele; Mucciarelli, Alessio; Ibata, Rodrigo +7 more
We present the metallicity and radial velocity for 450 bona fide members of the Sagittarius dwarf spheroidal (Sgr dSph) galaxy, measured from high-resolution spectra (R ≃ 18 000) obtained with FLAMES at the VLT. The targets were carefully selected (a) to sample the core of the main body of Sgr dSph while avoiding contamination from the central ste…
Quasars as standard candles. IV. Analysis of the X-ray and UV indicators of the disc-corona relation
Signorini, Matilde; Risaliti, Guido; Lusso, Elisabeta +4 more
Context. A non-linear relation between quasar monochromatic luminosities at 2500 Å and 2 keV holds at all observed redshifts and luminosities, and it has been used to derive quasar distances and to build a Hubble diagram of quasars. The choice of the X-ray and UV indicators has so far been somewhat arbitrary and has typically relied on photometric…
The pristine nature of SMSS 1605−1443 revealed by ESPRESSO
Rebolo, R.; Zapatero Osorio, M. R.; Allende Prieto, C. +20 more
Context. SMSS J160540.18−144323.1 is the carbon-enhanced metal-poor (CEMP) star with the lowest iron abundance ever measured, [Fe/H] = −6.2, which was first reported with the SkyMapper telescope. The carbon abundance is A(C)≈6.1 in the low-C band, as the majority of the stars in this metallicity range. Yet, constraining the isotopic ratio of key s…
Probing the nature of the low state in the extreme ultraluminous X-ray pulsar NGC 5907 ULX1
Salvaterra, R.; Pinto, C.; Israel, G. L. +13 more
NGC 5907 ULX1 is the most luminous ultra-luminous X-ray pulsar (ULXP) known to date, reaching luminosities in excess of 1041 erg s−1. The pulsar is known for its fast spin-up during the on-state. Here, we present a long-term monitoring of the X-ray flux and the pulse period between 2003 and 2022. We find that the source was i…