Search Publications
Are lithium-rich giants binaries? A radial velocity variability analysis of 1400 giants
Aguilera-Gómez, Claudia; Chanamé, Julio; Castro-Tapia, Matias
Context. The existence of low-mass giants with large amounts of lithium (Li) in their surfaces has challenged stellar evolution for decades. One of the possibilities usually discussed in the literature to explain these Li-rich giants involves the interaction with a close binary companion, a scenario that predicts that, when compared against their …
Effects of galaxy environment on merger fraction
White, G. J.; Małek, K.; Serjeant, S. +13 more
Aims: In this work we examine how environment influences the merger fraction, from the low density field environment to higher density groups and clusters. We also study how the properties of a group or cluster, as well as the position of a galaxy in the group or cluster, influences the merger fraction.
Methods: We identified galaxy grou…
Multi-iron subpopulations in Liller 1 from high-resolution H-band spectroscopy
Dalessandro, E.; Rich, R. M.; Fanelli, C. +7 more
We present a high-resolution chemical study of a representative sample of 21 luminous giant stars in Liller 1, a complex stellar system in the Galactic bulge, based on H-band spectra acquired with the Near-Infrared Spectrograph at KeckII. In this sample, we found fifteen stars with a subsolar iron abundance and enhanced [α/Fe] and [Al/Fe], likely …
Spectroscopic survey of faint planetary-nebula nuclei. III. A [WC] central star and two new PG1159 nuclei
Bond, Howard E.; Zeimann, Gregory R.; Werner, Klaus +1 more
We present spectroscopy of three hydrogen-deficient central stars of faint planetary nebulae, with effective temperatures (Teff) in excess of 100 000 K. The nucleus of RaMul 2 is a Population II Wolf-Rayet star of spectral type [WC], and the central stars of Abell 25 and StDr 138 are two new members of the PG1159 class. Our spectral ana…
LOFAR high-band antenna observations of the Perseus cluster: The discovery of a giant radio halo
Brunetti, G.; Shimwell, T. W.; Gastaldello, F. +13 more
The Perseus cluster is the brightest X-ray cluster in the sky and is known as a cool-core galaxy cluster. Being a very nearby cluster, it has been extensively studied. This has provided a comprehensive view of the physical processes that operate in the intracluster medium (ICM), including feedback from the active galactic nucleus (AGN) 3C 84 and m…
The discovery of two new benchmark brown dwarfs with precise dynamical masses at the stellar-substellar boundary
Ségransan, D.; Udry, S.; Forveille, T. +7 more
Aims: Measuring dynamical masses of substellar companions is a powerful tool for testing models of mass-luminosity-age relations as well as for determining observational features that constrain the boundary between stellar and substellar companions. In order to dynamically constrain the mass of such companions, we use multiple exoplanet measu…
First spiral arm detection using dynamical mass measurements of the Milky Way disk
Widmark, Axel; Naik, Aneesh P.
We applied the vertical Jeans equation to the Milky Way disk in order to study non-axisymmetric variations in the thin disk surface density. We divided the disk plane into area cells with a 100 pc grid spacing and used four separate subsets of the Gaia DR3 stars, defined by cuts in absolute magnitude, that reach distances up to 3 kpc. The vertical…
JOYS+ study of solid-state 12C/13C isotope ratios in protostellar envelopes: Observations of CO and CO2 ice with the James Webb Space Telescope
van Dishoeck, E. F.; Nazari, P.; Rocha, W. R. M. +12 more
Context. The carbon isotope ratio is a powerful tool for studying the evolution of stellar systems due to its sensitivity to the local chemical environment. Recent detections of CO isotopologs in disks and exoplanet atmospheres revealed a high variability in the isotope abundance, ponting towards significant fractionation in these systems. In orde…
INTEGRAL/IBIS polarization detection in the hard and soft intermediate states of Swift J1727.8−1613
Rodriguez, J.; Wilms, J.; Laurent, P. +5 more
Aims: Soft γ-ray emission (100 keV-10 MeV) has previously been detected in the hard state of several microquasars. In some sources, this emission was found to be highly polarized and was suggested to be emitted at the base of the jet. Until now, no γ-ray polarization had been found in any other state.
Methods: Using INTEGRAL/IBIS, we stu…
ViCTORIA project: The LOFAR view of environmental effects in Virgo cluster star-forming galaxies
Boselli, A.; Brüggen, M.; Ignesti, A. +5 more
Context. Environmental effects such as ram pressure stripping (RPS) shape the evolution of galaxies in dense regions.
Aims: We used the nearby Virgo cluster as a laboratory to study the environmental effects on the nonthermal components of star-forming galaxies.
Methods: We constructed a sample of 17 RPS galaxies in the Virgo cluster and…