Search Publications
Calibrating the metallicity of M dwarfs in wide physical binaries with F-, G-, and K-primaries - II: carbon, oxygen, and odd-Z iron-peak abundances of the primary stars
Caballero, J. A.; Montes, D.; Duque-Arribas, C. +1 more
Detailed chemical composition of stars is of prime interest for a range of topics in modern stellar astrophysics, such as the chemical evolution of the Galaxy or the formation, composition, and structure of exoplanets. In this work, we derive the C and O abundances and update Sc, V, Mn, and Co abundances considering hyperfine structure effects and…
The merger of hard binaries in globular clusters as the primary channel for the formation of second-generation stars
Kravtsov, Valery; Calderón, Francisco A.; Dib, Sami
We have recently presented observational evidence which suggests that the origin of the second-generation (G2) stars in globular clusters (GCs) is due to the binary-mediated collision of primordial (G1) low-mass main-sequence (MS) stars. This mechanism avoids both the mass budget problem and the need of external gas for dilution. Here, we report o…
NGC 5474 X-1: A neutron star ultraluminous X-ray source in an old stellar cluster?
Fabrika, Sergei; Atapin, Kirill; Vinokurov, Alexander +4 more
We present an optical and X-ray study of the ultraluminous X-ray source (ULX) NGC 5474 X-1. The X-ray spectrum taken during the bright state of the source (LX ~ 2 × 1040 erg s-1) shows signatures of a broad absorption line at ≃ 8 keV, which may be a cyclotron resonant scattering feature. This implies that this syst…
La Silla-QUEST RR Lyrae star survey II: the Crater II tidal streams
Girard, T.; Baltay, C.; Howard, R. +5 more
We describe photometry improvements in the La Silla-Quest RR Lyrae star (RRLS) survey that enable it to reach distances from the Sun (d⊙) ~140 kpc. We report the results of surveying ~300 deg2 of sky around the large, low-surface-brightness Crater II dwarf spheroidal galaxy. At d⊙ >80 kpc, we find a large overde…
Investigating the extinction and magnetic field geometry in the Bok globule CB26
Medhi, B. J.; Mazarbhuiya, A. M.; Das, H. S. +2 more
This study investigates the extinction properties, dust distribution, and magnetic field characteristics of the CB26 cloud. Extinction mapping, derived from near-infrared photometry, reveals a good correlation with the dust distribution, as traced by Herschel1SPIRE 500
An ultraviolet spectral study of fullerene-rich planetary nebulae
García-Hernández, D. A.; Gómez-Muñoz, M. A.; Manchado, A. +2 more
Several planetary nebulae (PNe) have been found to contain both polycyclic aromatic hydrocarbon (PAH-like) species and fullerenes (C60) distinguished by their mid-infrared emission. Previous laboratory and astronomical studies suggest that the formation of both species could be related to the decomposition, by photochemical processing, …
Role of ionizing background and galactic feedback in the redshift space clustering of O VI absorbers in hydrodynamical simulations
Srianand, Raghunathan; Maitra, Soumak; Mallik, Sukanya
We explore the effect of ionizing ultraviolet background (UVB) on the redshift space clustering of low-z (z ≤ 0.5) O VI absorbers using the Sherwood simulations incorporating 'WIND' (i.e. outflows driven by stellar feedback)-only and 'WIND + AGN (active galactic nucleus)' feedback. These simulations show positive clustering signals up to a scale o…
Variable white dwarfs in TMTS: asteroseismological analysis of a ZZ Ceti star, TMTS J17184064+2524314
Shi, Jianrong; Filippenko, Alexei V.; Esamdin, Ali +24 more
The Tsinghua University-Ma Huateng Telescope for Survey (TMTS) has been constantly monitoring the northern sky since 2020 in search of rapidly variable stars. To find variable white dwarfs (WDs), the TMTS catalogue is cross-matched with the WD catalogue of Gaia EDR3, resulting in over 3000 light curves of WD candidates. The WD TMTS J17184064+25243…
Offset of M54 from the Sagittarius dwarf spheroidal galaxy
Pace, Andrew B.; Walker, Matthew G.; An, Zhaozhou
We present results from simultaneous modelling of 2D (projected along the line of sight) position, proper motion, and line-of-sight velocity for Gaia- and Apache Point Observatory Galactic Evolution Experiment (APOGEE)-observed stars near the centre of the Sagittarius (Sgr) dwarf spheroidal galaxy. We use a mixture model that allows for independen…
Constraints on the ultra-high energy cosmic ray output of gamma-ray bursts
Gendre, B.; Orange, N. B.; Moore, E. +1 more
Ultra-high energy cosmic rays are the most extreme energetic particles detected on Earth, however, their acceleration sites are still mysterious. We explore the contribution of low-luminosity gamma-ray bursts to the ultra-high energy cosmic ray flux, since they form the bulk of the nearby population. We analyse a representative sample of these bur…