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The Massive CO White Dwarf in the Symbiotic Recurrent Nova RS Ophiuchi
Mikołajewska, Joanna; Shara, Michael M.
If accreting white dwarfs (WDs) in binary systems are to produce type Ia supernovae (SNe Ia), they must grow to nearly the Chandrasekhar mass and ignite carbon burning. Proving conclusively that a WD has grown substantially since its birth is a challenging task. Slow accretion of hydrogen inevitably leads to the erosion, rather than the growth of …
Cold dark matter plus not-so-clumpy dark relics
Mena, Olga; Gariazzo, Stefano; Weniger, Christoph +2 more
Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark matter scenarios, where the first component is a…
Resolving galaxy cluster gas properties at z 1 with XMM-Newton and Chandra
Arnaud, M.; Pratt, G. W.; Bartalucci, I. +3 more
Massive, high-redshift, galaxy clusters are useful laboratories to test cosmological models and to probe structure formation and evolution, but observations are challenging due to cosmological dimming and angular distance effects. Here we present a pilot X-ray study of the five most massive (M500 > 5 × 1014M⊙), …
Star formation of far-IR AGN and non-AGN galaxies in the green valley: possible implication of AGN positive feedback
Pović, Mirjana; Mahoro, Antoine; Nkundabakura, Pheneas
In this paper we present the star formation properties of Isubaru ≤ 23 X-ray detected active galactic nucleus (AGN) and non-AGN galaxies in the green valley with far-infrared (FIR) emission, using data from the COSMOS field. We measured star formation rates (SFR) using FIR Herschel/PACS data and we observed the location of AGN and non-A…
The Ca II infrared triplet's performance as an activity indicator compared to Ca II H and K. Empirical relations to convert Ca II infrared triplet measurements to common activity indices
Schmitt, J. H. M. M.; Schmidt, T. O. B.; Martin, J. +4 more
Aims: A large number of Calcium infrared triplet (IRT) spectra are expected from the Gaia and CARMENES missions. Conversion of these spectra into known activity indicators will allow analysis of their temporal evolution to a better degree. We set out to find such a conversion formula and to determine its robustness.
Methods: We have comp…
Very low-mass stellar content of the young supermassive Galactic star cluster Westerlund 1
Brandner, W.; Zinnecker, H.; de Marchi, G. +4 more
We present deep near-infrared HST/WFC3 observations of the young supermassive Galactic star cluster Westerlund 1 and an adjacent control field. The depth of the data is sufficient to derive the mass function for the cluster as a function of radius down to 0.15 M⊙ in the outer parts of the cluster. We identify for the first time a flatte…
3D shape of asteroid (6) Hebe from VLT/SPHERE imaging: Implications for the origin of ordinary H chondrites
Berthier, J.; Carry, B.; Delbo, M. +15 more
Context. The high-angular-resolution capability of the new-generation ground-based adaptive-optics camera SPHERE at ESO VLT allows us to assess, for the very first time, the cratering record of medium-sized (D 100-200 km) asteroids from the ground, opening the prospect of a new era of investigation of the asteroid belt's collisional history.
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New hard X-ray sources discovered in the ongoing INTEGRAL Galactic plane survey after 14 yr of observations
Sunyaev, Rashid A.; Tsygankov, Sergey S.; Lutovinov, Alexander A. +3 more
The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) continues to successfully work in orbit after its launch in 2002. The mission provides the deepest ever survey of hard X-ray sources throughout the Galaxy at energies above 20 keV. We report on a catalogue of new hard X-ray source candidates based on the latest sky maps comprising 14 y…
Vertical structure of the near-surface expanding ionosphere of comet 67P probed by Rosetta
Altwegg, K.; Behar, E.; Nilsson, H. +14 more
The plasma environment has been measured for the first time near the surface of a comet. This unique data set has been acquired at 67P/Churyumov-Gerasimenko during ESA/Rosetta spacecraft's final descent on 2016 September 30. The heliocentric distance was 3.8 au and the comet was weakly outgassing. Electron density was continuously measured with Ro…
Are star formation rates of galaxies bimodal?
Feldmann, Robert
Star formation rate (SFR) distributions of galaxies are often assumed to be bimodal with modes corresponding to star-forming and quiescent galaxies, respectively. Both classes of galaxies are typically studied separately, and SFR distributions of star-forming galaxies are commonly modelled as lognormals. Using both observational data and results f…