Search Publications
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…
Cool and data-driven: an exploration of optical cool dwarf chemistry with both data-driven and physical models
Casey, Andrew R.; Monty, Stephanie; Nordlander, Thomas +6 more
Detailed chemical studies of F/G/K - or solar-type - stars have long been routine in stellar astrophysics, enabling studies in both Galactic chemodynamics and exoplanet demographics. However, similar understanding of the chemistry of M and late-K dwarfs - the most common stars in the Galaxy - has been greatly hampered both observationally and theo…
The spin, expansion, and contraction of open star clusters
Jadhav, Vikrant V.; Kroupa, Pavel; Thies, Ingo +2 more
Context. Empirical constraints on the internal dynamics of open clusters are important for understanding their evolution and evaporation. High-precision astrometry from Gaia DR3 is thus useful to observe aspects of the cluster dynamics.
Aims: This work aims to identify dynamically peculiar clusters such as spinning and expanding clusters. We …
Turbulent Vortex with Moderate Dust Settling Probed by Scattering-induced Polarization in the IRS 48 System
Li, Zhi-Yun; Yang, Haifeng; Looney, Leslie W. +4 more
We investigate the crescent-shaped dust trap in the transition disk Oph IRS 48 using well-resolved (sub)millimeter polarimetric observations at ALMA Band 7 (870 µm). The dust polarization map reveals patterns consistent with dust-scattering-induced polarization. There is a relative displacement between the polarized flux and the total flux, …