Search Publications
Observed epochal variations in X-ray lines from the O supergiant ζ Puppis do not require substantial changes in the wind mass flux
Huenemoerder, David P.; Miller, Nathan A.; Pradhan, Pragati +2 more
We fit the high-resolution Chandra X-ray spectra of the O supergiant ζ Puppis using the variable boundary condition (VBC) line model to test the stability of its mass-loss rate between two epochs of observation: 2000 March and 2018 July - 2019 August. At issue is whether the observed variations are induced by global changes in the cool (unshocked)…
CONGRUENTS (COsmic-ray, Neutrino, Gamma-ray and Radio Non-Thermal Spectra) - II. Population-level correlations between galactic infrared, radio, and γ-ray emission
Thompson, Todd A.; Krumholz, Mark R.; Crocker, Roland M. +1 more
Galaxies obey a number of empirical correlations between their radio, γ-ray, and infrared emission, but the physical origins of these correlations remain uncertain. Here, we use the CONGRUENTS model for broad-band non-thermal emission from star-forming galaxies, which self-consistently calculates energy-dependent transport and non-thermal emission…
Testing the surface brightness fluctuation method on dwarf galaxies in the COSMOS field
Taylor, James E.; Blakeslee, John P.; Foster, Lauren M.
Dwarf galaxies are important tracers of small-scale cosmological structure, yet much of our knowledge about these systems comes from the limited sample of dwarf galaxies within the Local Group. To make a comprehensive inventory of dwarf populations in the local Universe, we require effective methods for deriving distance estimates for large number…
Primeval very low-mass stars and brown dwarfs - VIII. The first age benchmark L subdwarf, a wide companion to a halo white dwarf
Smart, R. L.; Raddi, R.; Pinfield, D. J. +12 more
We report the discovery of five white dwarf + ultracool dwarf systems identified as common proper motion wide binaries in the Gaia Catalogue of Nearby Stars. The discoveries include a white dwarf + L subdwarf binary, VVV 1256-62AB, a gravitationally bound system located 75.6$^{+1.9}_{-1.8}$ pc away with a projected separation of 1375$^{+35}_{-33}$…
The impact of periastron passage on the X-ray and optical properties of the Symbiotic System R Aquarii
Guerrero, M. A.; Toalá, J. A.; Karovska, M. +4 more
Multi-epoch Chandra and XMM-Newton observations of the symbiotic system R Aquarii (R Aqr) spanning 22 yr are analysed by means of a reflection model produced by an accretion disc. This methodology helps dissecting the contribution from different components in the X-ray spectra of R Aqr: the soft emission from the jet and extended emission, the hea…
Effect of temperature on measurement of fundamental constants using white dwarfs in Gaia-EDR3 survey
Uniyal, Akhil; Kalita, Surajit; Chakrabarti, Sayan
Fundamental constants are crucial for comprehending physical mechanisms, but their measurements contain uncertainties due to experimental limitations. We investigate the impact of system temperature on these uncertainties using nearby white dwarfs observed in the Gaia Early Data Release 3 (EDR3) survey. Using the structures of these white dwarfs, …
X-ray detection of the most extreme star-forming galaxies at the cosmic noon via strong lensing
Frye, Brenda L.; Yun, Min S.; Liu, Daizhong +11 more
Hyperluminous infrared galaxies (HyLIRGs) are the most extreme star-forming systems observed in the early Universe, and their properties still elude comprehensive understanding. We have undertaken a large XMM-Newton observing programme to probe the total accreting black hole population in three HyLIRGs at z = 2.12, 3.25, and 3.55, gravitationally …
Particle acceleration at the bow shock of runaway star LS 2355: non-thermal radio emission but no γ-ray counterpart
Motta, S.; van den Eijnden, J.; Mohamed, S. +3 more
Massive stars that travel at supersonic speeds can create bow shocks as their stellar winds interact with the surrounding interstellar medium (ISM). These bow shocks - prominent sites for mechanical feedback of individual massive stars - are predominantly observed in the infrared (IR) band. Confirmed high-energy emission from stellar bow shocks ha…
Discovery of Globular Cluster Candidates in the Dwarf Irregular Galaxy IC 2574 Using HST/ACS Imaging
Forbes, Duncan A.; Read, Justin I.; Collins, Michelle L. M. +1 more
We report the discovery of 23 globular cluster (GC) candidates around the relatively isolated dwarf galaxy IC 2574 within the Messier 81 (M81) group, at a distance of 3.86 Mpc. We use observations from the HST Advanced Camera for Surveys (ACS) to analyse the imaging in the F814W and F555W broad-band filters. Our GC candidates have luminosities ran…
The stellar occultation by (319) Leona on 2023 September 13 in preparation for the occultation of Betelgeuse
Gutiérrez, P. J.; Luque-Escamilla, P. L.; Alvarez-Candal, A. +43 more
On 2023 December 12, the star α Orionis will be occulted by asteroid (319) Leona. This represents an extraordinary and unique opportunity to analyse the brightness distribution of Betelgeuse's photosphere with extreme angular resolution by studying light curves from different points on Earth and at different wavelengths. Here we present observatio…