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The metal-poor end of the Spite plateau. II. Chemical and dynamical investigation
Steffen, M.; Bonifacio, P.; Caffau, E. +7 more
Context. The study of old, metal-poor stars deepens our knowledge on the early stages of the universe. In particular, the study of these stars gives us a valuable insight into the masses of the first massive stars and their emission of ionising photons.
Aims: We present a detailed chemical analysis and determination of the kinematic and orbit…
Young giants of intermediate mass. Evidence of rotation and mixing
Mucciarelli, Alessio; Meynet, Georges; Bonifacio, Piercarlo +7 more
Context. In the search of a sample of metal-poor bright giants using Strömgren photometry, we serendipitously found a sample of 26 young (ages younger than 1 Gyr) metal-rich giants, some of which have high rotational velocities.
Aims: We determined the chemical composition and rotational velocities of these stars in order to compare them with…
ALMA resolves giant molecular clouds in a tidal dwarf galaxy
Moore, T. J. T.; Meidt, S. E.; Schinnerer, E. +12 more
Tidal dwarf galaxies (TDGs) are gravitationally bound condensations of gas and stars that formed during galaxy interactions. Here we present multi-configuration ALMA observations of J1023+1952, a TDG in the interacting system Arp 94, where we resolved CO(2-1) emission down to giant molecular clouds (GMCs) at 0.64″∼45 pc resolution. We find a remar…
The Diverse Morphologies and Structures of Dwarf Galaxies Hosting Optically Selected Active Massive Black Holes
Greene, Jenny E.; Geha, Marla; Schutte, Zachary +2 more
We present a study of 41 dwarf galaxies hosting active massive black holes (BHs) using Hubble Space Telescope observations. The host galaxies have stellar masses in the range of M⋆ ∼ 108.5-109.5 M⊙ and were selected to host active galactic nuclei (AGNs) based on narrow emission line ratios derived from S…
Progenitor mass constraints for the type Ib intermediate-luminosity SN 2015ap and the highly extinguished SN 2016bau
Filippenko, Alexei V.; Pandey, S. B.; Buckley, David A. H. +21 more
Photometric and spectroscopic analyses of the intermediate-luminosity Type Ib supernova (SN) 2015ap and of the heavily reddened Type Ib SN 2016bau are discussed. Photometric properties of the two SNe, such as colour evolution, bolometric luminosity, photospheric radius, temperature, and velocity evolution, are also constrained. The ejecta mass, sy…
Two Classes of Eruptive Events During Solar Minimum
Yeates, A. R.; Bhowmik, P.
During solar minimum, the Sun is relatively inactive with few sunspots observed on the solar surface. Consequently, we observe a smaller number of highly energetic events such as solar flares or coronal mass ejections (CMEs), which are often associated with active regions on the photosphere. Nonetheless, our magnetofrictional simulations during th…
Impact of magnetic activity on inferred stellar properties of main-sequence Sun-like stars
Chaplin, William J.; Basu, Sarbani; Miglio, Andrea +3 more
The oscillation frequencies observed in Sun-like stars are susceptible to being shifted by magnetic activity effects. The measured shifts depend on a complex relationship involving the mode type, the field strength, and spatial distribution of activity, as well as the inclination angle of the star. Evidence of these shifts is also present in frequ…
Astrometric radial velocities for nearby stars
Lindegren, Lennart; Dravins, Dainis
Context. Under certain conditions, stellar radial velocities can be determined from astrometry, without any use of spectroscopy. This enables us to identify phenomena, other than the Doppler effect, that are displacing spectral lines.
Aims: The change of stellar proper motions over time (perspective acceleration) is used to determine radial v…
Modelling heterogeneous dust particles: an application to cometary polarization
Halder, Prithish; Ganesh, Shashikiran
In this work, we introduce a comet dust model that incorporates multiple dust morphologies along with inhomogeneous mixture of silicate minerals and carbonaceous materials under power-law size distribution, to replicate the standard polarization-phase curve observed in several comets in the narrow-band continuum. Following the results from Rosetta…
Discovery of Double-ring Structure in the Supernova Remnant N103B: Evidence for Bipolar Winds from a Type Ia Supernova Progenitor
Acero, Fabio; Yamaguchi, Hiroya; Chu, You-Hua +1 more
The geometric structure of supernova remnants (SNR) provides a clue to unveiling the pre-explosion evolution of their progenitors. Here we present an X-ray study of N103B (0509-68.7), a Type Ia SNR in the Large Magellanic Cloud, that is known to be interacting with dense circumstellar matter (CSM). Applying our novel method for feature extraction …