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The peculiar ejecta of the nova V1425 Aquilae
Schmidtobreick, L.; Celedón, L.; Tappert, C.
Many important details of the mechanisms underlying the ejection of material during a (classical) nova eruption are still not understood. Here we present optical spectroscopy and narrow-band images of the nova V1425 Aql, 23 yr after the nova eruption. We find that the ejecta consist of two significantly different components. The first resembles wh…
Did Kepler-444 have a long-lived convective core?
Stokholm, Amalie; Verma, Kuldeep; Aguirre Børsen-Koch, Víctor +2 more
With the greater power to infer the state of stellar interiors provided by asteroseismology, it has become possible to study the survival of initially convective cores within stars during their main-sequence evolution. Standard theories of stellar evolution predict that convective cores in subsolar mass stars have lifetimes below $1\, {\rm Gyr}$. …
Type II and anomalous Cepheids in the Kepler K2 mission
Bódi, Attila; Szabó, Róbert; Molnár, László +4 more
We present the results of the analysis of Type II and anomalous Cepheids using the data from the Kepler K2 mission. The precise light curves of these pulsating variable stars are the key to study the details of their pulsation, such as the period-doubling effect or the presence of additional modes. We applied the Automated Extended Aperture Photom…
An Update of the Catalog of Radial Velocity Standard Stars from the APOGEE DR17
Huang, Yang; Luo, A. -Li; Dong, Xiao-Bo +2 more
We present an updated catalog of 46,753 radial velocity (RV) standard stars selected from the APOGEE DR17. These stars cover the Northern and Southern Hemispheres almost evenly, with 62% being red giants and 38% being main sequence stars. These RV standard stars are stable on a baseline longer than 200 days (with 54% longer than one year and 10% l…
Effects of the Ionospheric Conductance on the Dynamics of the Magnetotail
El-Alaoui, Mostafa; Walker, Raymond J.; McPherron, Robert L.
We have carried out a series of numerical experiments designed to evaluate the sensitivity of global magnetohydrodynamic simulations to changes in ionospheric conductance. We multiplied the precipitating energy fluxes due to both strong pitch angle scattering and parallel currents by constant factors in the Robinson et al. (1987,
On the true nature of the contact binary CRTS J192848.7‑404555
Filipović, Miroslav; Wadhwa, Surjit S.; DeHorta, Ain Y. +1 more
CRTS J192848.7‑404555 was recognized as a potential contact binary merger candidate on the basis of survey photometry analysis. We have carried out follow‑up ground‑based photometry of the system and showed that at the recorded coordinates for the system, there are two stars approximately 3 s of arc apart. Our analysis shows that the fainter of th…
Determination of the eddy diffusion in the Venusian clouds from VeRa sulfuric acid observations
Sheng, Zheng; Dai, Longkang; Shao, Wencheng +1 more
Context. The vertical eddy diffusion coefficient (Kzz) characterizing the efficiency of vertical atmospheric mixing is essential for 1D planetary atmospheric modeling, but poorly constrained in the Venusian clouds, where our ability to observe tracer gases is limited. The Venusian clouds are mainly composed of H2SO4
Very Metal-poor Stars in the Solar Vicinity: Kinematics and Abundance Analysis
Villanova, Sandro; Carraro, Giovanni; Plotnikova, Anastasiia +1 more
Very metal-poor stars contain crucial information on the Milky Way's infancy. In our previous study we derived a mean age of ~13.7 Gyr for a sample of these stars in the Sun's vicinity. In this work, we investigate the chemical and kinematic properties of these stars with the goal of obtaining some insights into their origin and their parent popul…
Origin of the complex iron line structure and spectral variation in Mrk 766
Ebisawa, Ken; Mizumoto, Misaki; Mochizuki, Yuto
Complex Fe-K emission/absorption line features are commonly observed in the 6-11 keV band from Active Galactic Nuclei (AGN). These features are formed in various physical components surrounding the black holes. The Narrow-Line Seyfert 1 (NLS1) galaxy Mrk 766, in particular, exhibits characteristic blue-shifted Fe-K absorption lines caused by the u…
Mid-IR Observations of IRAS, AKARI, WISE/NEOWISE, and Subaru for Large Icy Asteroid (704) Interamnia: A New Perspective of Regolith Properties and Water Ice Fraction
Zhao, Yuhui; Ji, Jianghui; Yang, Bin +3 more
(704) Interamnia is one of the largest asteroids located in the outer main-belt region, which may contain a large amount of water ice underneath its surface. We observe this asteroid using 8.2 m Subaru telescope at mid-infrared wave bands and utilize a thermophysical model for realistic surface layers to analyze mid-infrared data from Subaru along…