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Models for metal-poor stars with different initial abundances of C, N, O, Mg, and Si. II. Application to the colour-magnitude diagrams of the globular clusters 47 Tuc, NGC 6362, M 5, M 3, M 55, and M92
Casagrande, Luca; Edvardsson, Bengt; VandenBerg, Don A.
Stellar models for -2.5 ≤ [Fe/H] ≤-0.5 that have been computed for variations in the C:N:O abundance ratio (for two different values of [CNO/Fe]) are compared with HST Wide Field Camera 3 (WFC3) observations of the globular clusters (GCs) 47 Tuc, NGC 6362, M 5 M 3, M 55, and M 92. The bolometric corrections (BCs) used to transpose the models to th…
Mars-Ward Ion Flows in the Martian Magnetotail: Mars Express Observations
Barabash, Stas; Nilsson, Hans; Rong, Zhaojin +10 more
We investigate Mars-ward planetary ions (O+ and O2+) in the Martian magnetotail that potentially reduce the amount of escaping ions. The global properties of Mars-ward flows in the Martian magnetotail are characterized, based on over 13-years of ion data (May 2007-December 2020) collected by the Analyzer of Space P…
Low-metallicity globular clusters in the low-mass isolated spiral galaxy NGC 2403
Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P. +4 more
The globular cluster (GC) systems of low-mass late-type galaxies, such as NGC 2403, have been poorly studied to date. As a low mass galaxy (M* = 7 × 109 M⊙), cosmological simulations predict NGC 2403 to contain few, if any, accreted GCs. It is also isolated, with a remarkably undisturbed HI disc. Based on candidate…
White-light QFP wave train and the associated failed breakout eruption
Yao, Surui; Shen, Yuandeng; Zhou, Chengrui +5 more
Quasi-periodic fast-propagating (QFP) magnetosonic wave trains are commonly observed in the low corona at extreme ultraviolet wavelength bands. Here, we report the first white-light imaging observation of a QFP wave train propagating outwardly in the outer corona ranging from 2 to 4 R⊙. The wave train was recorded by the Large Angle Spe…
Dynamo activity of the K dwarf KOI-883 from transit photometry mapping
Marsden, S. C.; Carter, B. D.; Valio, A. +1 more
The Kepler mission target star KOI-883 is notable in being a low-mass K2V dwarf with moderately fast 8.99-d rotation and hosting a single transiting hot Jupiter in a 2.69-d orbit. This combination thus presents a particular opportunity to study star-spot activity by using the many deep planetary transits apparent in the light curve to map the stel…
Simultaneous Detection of Optical Flares of the Magnetically Active M-dwarf Wolf359
Wang, Shiang-Yu; Zhang, Yu; Lehner, Matthew J. +13 more
We present detections of stellar flares of Wolf 359, an M6.5 dwarf in the solar neighborhood (2.41 pc) known to be prone to flares due to surface magnetic activity. The observations were carried out from 2020 April 23 to 29 with a 1 m and a 0.5 m telescope separated by nearly 300 km in Xinjiang, China. In 27 hr of photometric monitoring, a total o…
Extremely Inclined Orbit of the S-type Planet γ Cep Ab Induced by the Eccentric Kozai-Lidov Mechanism
Ji, Jianghui; Huang, Xiumin
γ Cep Ab is a typical S-type planet, which occupies a nearly perpendicular planetary orbit relative to the binary. Here, we use a Markov Chain Monte Carlo sampler to conduct a full N-body fitting and derive self-consistent orbital solutions for this hierarchical system. We then employ the eccentric Kozai-Lidov (EKL) mechanism to explain the extrem…
Pushing sub-arcsecond resolution imaging down to 30 MHz with the trans-European International LOFAR Telescope
Bondi, M.; Brunetti, G.; Callingham, J. R. +12 more
Relatively little information is available about the Universe at ultra-low radio frequencies (ULF; i.e., below 50 MHz), although the ULF spectral window contains a wealth of unique diagnostics for studying galactic and extragalactic phenomena. Subarcsecond resolution imaging at these frequencies is extremely difficult, due to the long baselines (&…
Discovery of Nine Super Li-rich Unevolved Stars from the LAMOST Survey
Wang, L.; Shi, J. -R.; Zhou, Y. -T. +7 more
Based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution spectroscopic survey (MRS), we report the discovery of nine super Li-rich unevolved stars with A(Li) > 3.8 dex. These objects show unusually high levels of lithium abundances, up to three times higher than the meteoritic value of 3.3 dex, which ind…
Gaia-ESO Survey: Detailed elemental abundances in red giants of the peculiar globular cluster NGC 1851
Gilmore, G.; Guiglion, G.; Lardo, C. +24 more
Context. NGC 1851 is one of several globular clusters for which multiple stellar populations of the subgiant branch have been clearly identified and a difference in metallicity detected. A crucial piece of information on the formation history of this cluster can be provided by the sum of A(C+N+O) abundances. However, these values have lacked a gen…