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GTC Follow-up Observations of Very Metal-poor Star Candidates from DESI
Cunha, Katia; Smith, Verne V.; Moustakas, John +48 more
The observations from the Dark Energy Spectroscopic Instrument (DESI) will significantly increase the numbers of known extremely metal-poor stars by a factor of ~10, improving the sample statistics to study the early chemical evolution of the Milky Way and the nature of the first stars. In this paper we report follow-up observations with high sign…
Asteroseismology of double-mode radial δ Scuti stars: AE Ursae Majoris and RV Arietis
Daszyńska-Daszkiewicz, J.; Walczak, P.; Szewczuk, W. +1 more
We construct complex seismic models of two high-amplitude δ Sct stars, AE UMa and RV Ari, each pulsating in two radial modes: fundamental and first overtone. Besides the frequencies of two radial modes, the models also reproduce the amplitude of bolometric flux variations (the non-adiabatic parameter f) for the dominant mode. Applying the Monte-Ca…
HelioCast: heliospheric forecasting based on white-light observations of the solar corona
Poirier, Nicolas; Kouloumvakos, Athanasios; Indurain, Mikel +8 more
We present a new 3D magnetohydrodynamic (MHD) heliospheric model for space-weather forecasting driven by boundary conditions defined from white-light observations of the solar corona. The model is based on the MHD code PLUTO, constrained by an empirical derivation of the solar wind background properties at 0.1 au. This empirical method uses white-…
HALO7D. III. Chemical Abundances of Milky Way Halo Stars from Medium-resolution Spectra
Guhathakurta, Puragra; Kirby, Evan N.; Cunningham, Emily C. +4 more
The Halo Assembly in Lambda Cold Dark Matter: Observations in 7 Dimensions (HALO7D) survey measures the kinematics and chemical properties of stars in the Milky Way (MW) stellar halo to learn about the formation of our Galaxy. HALO7D consists of Keck II/DEIMOS spectroscopy and Hubble Space Telescope-measured proper motions of MW halo main-sequence…
Unveiling polarized emission from interstellar dust of the Large Magellanic Cloud with Planck
Hughes, A.; Alina, D.; Lazarian, A. +5 more
Polarization of interstellar dust emission is a powerful probe of dust properties and magnetic field structure. Yet studies of external galaxies are hampered by foreground dust contribution. The study aims at separating the polarized signal from the Large Magellanic Cloud (LMC) from that of the Milky Way (MW) to construct a wide-field, spatially c…
Planetary companions orbiting the M dwarfs GJ 724 and GJ 3988. A CARMENES and IRD collaboration
Kuzuhara, M.; Tamura, M.; Kudo, T. +36 more
We report the discovery of two exoplanets around the M dwarfs GJ 724 and GJ 3988 using the radial velocity (RV) method. We obtained a total of 153 3.5 m Calar Alto/CARMENES spectra for both targets and measured their RVs and activity indicators. We also added archival ESO/HARPS data for GJ 724 and infrared RV measurements from Subaru/IRD for GJ 39…
Discovery of the shell structure via break radii in the outer halo of the Milky Way
Shi, Jianrong; Ma, Jun; Ye, Dashuang +1 more
Based on the Gaia DR3 RR Lyrae catalogue, we use two methods to fit the density profiles with an improved broken power law, and find that there are two break radii coinciding with the two apocentre pile-ups of high-eccentricity Gaia-Sausage-Enceladus (GSE) merger. Also, there is a break caused by the Sagittarius (Sgr) stream. Combining the positio…
A novel approach to detect line emission under high background in high-resolution X-ray spectra
Karovska, Margarita; Zhang, Xiangyu; Kashyap, Vinay +1 more
We develop a novel statistical approach to identify emission features or set upper limits in high-resolution spectra in the presence of high background. The method relies on detecting differences from the background using smooth tests and using classical likelihood ratio tests to characterize known shapes like emission lines. We perform signal det…
A different view of wind in X-ray binaries: the accretion disc corona source 2S 0921-630
Done, Chris; Tanimoto, Atsushi; Odaka, Hirokazu +1 more
Accretion disc coronae (ADC) sources are very high inclination neutron star or black hole binaries, where the outer accretion flow blocks a direct view of the central source. The weak observed X-ray emission is instead produced mainly by scattering of the intrinsic radiation from highly ionized gas surrounding the source, the ADC. However, the ori…
The Neptunian gravity estimated from the motion of Triton based on astrometric observations
Yuan, Ye; Yan, Jianguo; Wang, Bo +4 more
Context. Accurate gravity and ephemerides estimations for Neptune and its satellites are necessary for the forthcoming deep space exploration missions targeting its system. In addition, these estimations are also meaningful for the modeling of Neptune's interior and for solar system dynamics studies. The body of astrometric data concerning Triton …