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Combined Gemini-South and HST photometric analysis of the globular cluster NGC 6558: The age of the metal-poor population of the Galactic bulge
Bica, E.; Nardiello, D.; Barbuy, B. +8 more
Context. NGC 6558 is a low-galactic-latitude globular cluster projected in the direction of the Galactic bulge. Due to high reddening, this region presents challenges in deriving accurate parameters, which require meticulous photometric analysis. We present a combined analysis of near-infrared and optical photometry from multi-epoch high-resolutio…
From gas to stars: MUSEings on the internal evolution of IC 1613
Iorio, G.; Kacharov, N.; Skillman, E. D. +9 more
Context. The kinematics and chemical composition of stellar populations of different ages provide crucial information on the evolution of the various components of a galaxy. Aim. Our aim is to determine the kinematics of individual stars as a function of age in IC 1613, a star-forming, gas-rich, and isolated dwarf galaxy of the Local Group (LG). M…
The acoustic size of the Sun
Gough, D. O.; Takata, M.
Analysis of f-mode frequencies has provided a measure of the radius of the Sun which is lower, by a few hundredths per cent, than the photospheric radius determined by direct optical measurement. Part of this difference can be understood by recognizing that it is primarily the variation of density well beneath the photosphere of the star that dete…
JWST imaging of the closest globular clusters—I. Possible infrared excess among white dwarfs in NGC 6397
Salaris, M.; Apai, D.; Anderson, J. +9 more
We present James Webb Space Telescope observations of the globular cluster NGC 6397 and use them to extend to infrared wavelengths the characterization of the cluster's entire white dwarf (WD) cooling sequence (CS). The data allows us to probe fundamental astrophysical WD properties and to search for evidence in their colors for (or against) the e…
The extraordinary frequency pattern variation in δ Scuti stars
Balona, Luis A.
Inspection of the periodograms of TESS delta Scuti stars indicates that there is little, if any, similarity between the frequencies of stars in the same region of the H-R diagram. This is difficult to understand because pulsation models predict that stars with similar physical parameters should have similar frequencies. To investigate the problem,…
Weak gravitational lensing measurements of Abell 2744 using JWST and shear measurement algorithm pyRRG-JWST
Massey, Richard; Harvey, David R.
We update the publicly available weak lensing shear measurement algorithm pyRRG for the JWST, and apply it to UNCOVER DR1 imaging of galaxy cluster Abell 2744. At short wavelengths (${\lt}2.5\, \mu$m), shear measurements are consistent between independent observations through different JWST bandpasses, and calibrated within 1.5 per cent of those f…
Compact Binary Formation in Open Star Clusters II: Difficulty of Gaia NS formation in low-mass star clusters
Wang, Long; Fujii, Michiko S.; Tanikawa, Ataru
Gaia mission offers opportunities to search for compact binaries not involved in binary interactions (hereafter inert compact binaries), and results in the discoveries of binaries containing one black hole (BH) or one neutron star (NS), called "Gaia BHs'' and"Gaia NSs'', respectively. We have assessed if Gaia BHs and NSs can be formed in open clus…
Cepheid Metallicity in the Leavitt Law (C-MetaLL) survey: VI. Radial abundance gradients of 29 chemical species in the Milky Way disc
Ripepi, V.; Molinaro, R.; Marconi, M. +9 more
Context. Classical Cepheids (DCEPs) are crucial for calibrating the extragalactic distance ladder, ultimately enabling the determination of the Hubble constant through the period-luminosity (PL) and period-Wesenheit (PW) relations that they exhibit. Hence, it is vital to understand how the PL and PW relations depend on metallicity. This is the pur…
The original composition of the gas forming first-generation stars in clusters: Insights from HST and JWST
Milone, A. P.; Cordoni, G.; Marino, A. F. +8 more
Globular cluster (GC) stars composed of pristine material, also known as first-generation (1G) stars, are not chemically homogeneous as they exhibit extended sequences in the chromosome map (ChM). Recent studies characterized 1G stars within the center of 55 Galactic GCs, revealing metallicity variations. Despite this progress, several unanswered …
The Long-term Spin-down Trend of Ultraluminous X-Ray Pulsar M82 X-2
Liu, Jiren
The discovery in 2014 of the pulsation from the ultraluminous X-ray source (ULX) M82 X-2 has changed our view of ULXs. Because of the relatively short baseline over which pulsations have been detected so far, M82 X-2's spin state had been assumed to be in an equilibrium state. Using Chandra and XMM-Newton archive data, we are able to investigate t…