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Recurrent Symbiotic Nova T Coronae Borealis before Outburst
Strakhov, I. A.; Tatarnikov, A. M.; Shenavrin, V. I. +5 more
The results of photometric and spectral observations of T CrB obtained in a wide range of wavelengths in 2011-2023 are presented. We use the near-IR light curves to determine a new ephemeris $JD_{\textrm{min}}=2455828.9+227.55E$ for the times of light minima when the red giant is located between the observer and the hot component. The flux ratio H…
A constrained cosmological model in f(R ,Lm) gravity
Singh, J. K.; Shaily; Myrzakulov, Ratbay +1 more
In this article, we study the expanding nature of the universe in the context of f(R ,Lm) gravity theory, here R represents the Ricci scalar and Lm is the matter Lagrangian density. With a specific form of f(R ,Lm) , we obtain the field equations for flat FLRW metric. We parametrize the deceleration parameter in te…
Age of FGK Dwarfs Observed with LAMOST and GALAH: Considering the Oxygen Enhancement
Bird, Sarah A.; Wu, Yaqian; Bi, Shaolan +11 more
Varying oxygen abundance could impact modeling-inferred ages. This work aims to estimate the ages of dwarfs considering observed oxygen abundance. To characterize 67,503 LAMOST and 4006 GALAH FGK-type dwarf stars, we construct a grid of stellar models, which take into account oxygen abundance as an independent model input. Compared with ages deter…
MeV Gamma-Ray Source Contribution to the Inner Galactic Diffuse Emission
Mukherjee, Reshmi; Yoneda, Hiroki; Inoue, Yoshiyuki +2 more
The origin of the inner Galactic emission, measured by COMPTEL with a flux of ~10-2 MeV cm-2 s-1 sr-1 in the 1-30 MeV energy range from the inner Galactic region, has remained unsettled since its discovery. In this paper, we elaborate on a model of individual MeV gamma-ray sources unresolved by COMPTEL. …
Globular cluster ultraluminous X-ray sources in the furthest early-type galaxies
Kundu, Arunav; Dage, Kristen C.; Zepf, Stephen E. +5 more
Ultraluminous X-ray sources (ULXs) in globular clusters (GCs) are low-mass X-ray binaries that achieve high X-ray luminosities through a currently uncertain accretion mechanism. Using archival Chandra and Hubble Space Telescope observations, we perform a volume-limited search (≲70 Mpc) of 21 of the most massive ($\gt 10^{11.5} \, \mathrm{M}_\odot$…
Search for Ultralight Dark Matter with a Frequency Adjustable Diamagnetic Levitated Sensor
Zhang, Liang; Li, Rui; Lin, Shaochun +3 more
Among several dark matter candidates, bosonic ultra-light (sub-meV) dark matter is well motivated because it could couple to the Standard Model and induce new forces. Previous MICROSCOPE and Eöt-Wash torsion experiments have achieved high accuracy in the sub-1 Hz region. However, at higher frequencies there is still a lack of relevant experimental…
An Independent Determination of the Distance to Supernova SN 1987A by Means of the Light Echo AT 2019xis
Baade, Dietrich; Wang, Lifan; Höflich, Peter +5 more
Accurate distance determination to astrophysical objects is essential for the understanding of their intrinsic brightness and size. The distance to SN 1987A has been previously measured by the expanding photosphere method and by using the angular size of the circumstellar rings with absolute sizes derived from light curves of narrow UV emission li…
Origins of the UV/X-ray relation in Arakelian 120
Done, C.; Porquet, D.; Lobban, A. +1 more
We explore the accretion geometry in Arakelian 120 using intensive UV and X-ray monitoring from Swift. The hard X-rays (1-10 keV) show large amplitude, fast (few-day) variability, so we expect reverberation from the disc to produce UV variability from the varying hard X-ray illumination. We model the spectral energy distribution (SED) including an…
Exploring source region of 3-min slow magnetoacoustic waves observed in coronal fan loops rooted in sunspot umbra
Gupta, Girjesh R.; Rawat, Ananya
Sunspots host various oscillations and wave phenomena like umbral flashes, umbral oscillations, running penumbral waves, and coronal waves. All fan loops rooted in sunspot umbra constantly show a 3-min period propagating slow magnetoacoustic waves in the corona. However, their origin in the lower atmosphere is still unclear. In this work, we studi…
Observational signatures of carbon-oxygen white dwarf merger remnants
Goulding, Andy; Quataert, Eliot; Yao, Philippe Z.
Many double white dwarf (WD) mergers likely do not lead to a prompt thermonuclear explosion. We investigate the prospects for observationally detecting the surviving remnants of such mergers, focusing on the case of mergers of double Carbon-Oxygen WDs. For ~104 yr, the merger remnant is observationally similar to an extreme AGB star evo…