Search Publications
IC 4499 revised: Spectro-photometric evidence of small light-element variations
Dalessandro, E.; Salaris, M.; Bastian, N. +6 more
It has been suggested that IC 4499 is one of the very few old globulars to not host multiple populations with light-element variations. To follow-up on this very interesting result, here we have made use of accurate HST photometry and FLAMES at VLT high-resolution spectroscopy to investigate in more detail the stellar population properties of this…
S stars and s-process in the Gaia era. I. Stellar parameters and chemical abundances in a sub-sample of S stars with new MARCS model atmospheres
Jorissen, A.; Escorza, A.; Van Winckel, H. +6 more
Context. S stars are transition objects between M-type giants and carbon stars on the asymptotic giant branch (AGB). They are characterized by overabundances of s-process elements. Roughly half of them are enhanced in technetium (Tc), an s-process element with no stable isotope, while the other half lack technetium. This dichotomy arises from the …
Chemical inhomogeneities amongst first population stars in globular clusters. Evidence for He variations
Dalessandro, E.; Salaris, M.; Cabrera-Ziri, I. +3 more
Spreads in light element abundances among stars (also known as multiple populations) are observed in nearly all globular clusters. One way to map such chemical variations using high-precision photometry is to employ a suitable combination of stellar magnitudes in the F275W, F336W, F438W, and F814W filters (called the "chromosome map"), to maximise…
Predicted microlensing events from analysis of Gaia Data Release 2
Bramich, D. M.
Context. Astrometric microlensing can be used to make precise measurements of the masses of lens stars that are independent of their assumed internal physics. Such direct mass measurements, obtained purely by observing the gravitational effects of the stars on external objects, are crucial for validating theoretical stellar models. Specifically, a…
Cometary ion dynamics observed in the close vicinity of comet 67P/Churyumov-Gerasimenko during the intermediate activity period
Behar, E.; Nilsson, H.; Goetz, C. +4 more
Aims: Cometary ions are constantly produced in the coma, and once produced they are accelerated and eventually escape the coma. We describe and interpret the dynamics of the cometary ion flow, of an intermediate active comet, very close to the nucleus and in the terminator plane.
Methods: We analysed in situ ion and magnetic field measur…
Integrated-light analyses vs. colour-magnitude diagrams. II. Leo A: an extremely young dwarf in the Local Group
Monelli, M.; Gallart, C.; Bernard, E. J. +7 more
Context. Most of our knowledge of the stellar component of galaxies is based on the analysis of distant systems and comes from integrated light data. It is important to test whether the results of the star formation histories (SFH) obtained with standard full-spectrum fitting methods are in agreement with those obtained through colour-magnitude di…
HERschel Observations of Edge-on Spirals (HEROES). IV. Dust energy balance problem
Holwerda, Benne W.; Clark, Christopher J. R.; Mosenkov, Aleksandr V. +15 more
We present results of the detailed dust energy balance study for the seven large edge-on galaxies in the HEROES sample using three-dimensional (3D) radiative transfer (RT) modelling. Based on available optical and near-infrared (NIR) observations of the HEROES galaxies, we derive the 3D distribution of stars and dust in these galaxies. For the sak…
Herschel and SCUBA-2 observations of dust emission in a sample of Planck cold clumps
Ward-Thompson, Derek; Fuller, Gary; Kim, Kee-Tae +26 more
Context. Analysis of all-sky Planck submillimetre observations and the IRAS 100 µm data has led to the detection of a population of Galactic cold clumps. The clumps can be used to study star formation and dust properties in a wide range of Galactic environments.
Aims: Our aim is to measure dust spectral energy distribution (SED) variati…
Recurring obscuration in NGC 3783
Kaastra, J. S.; Kriss, G. A.; Bianchi, S. +14 more
Context. Obscuration of the continuum emission from active galactic nuclei by streams of gas with relatively high velocity (>1000 km s-1) and column density (>3 × 1025 m-2) has been seen in a few Seyfert galaxies. This obscuration has a transient nature. In December 2016 we witnessed such an event in NGC 3783…
Rotating network jets in the quiet Sun as observed by IRIS
Srivastava, A. K.; Murawski, K.; Dwivedi, B. N. +1 more
Aims: We perform a detailed observational analysis of network jets to understand their kinematics, rotational motion, and underlying triggering mechanism(s). We analyzed the quiet-Sun (QS) data.
Methods: IRIS high-resolution imaging and spectral observations (slit-jaw images: Si IV 1400.0 Å; raster: Si IV 1393.75 Å) were used to analyze …