arXiv subjects

Jan J. Eldridge

Publications and source records attributed to Jan J. Eldridge.

21 records · Page 2Linked to original sources

arXiv2022

Nested Dust Shells around the Wolf-Rayet Binary WR 140 observed with JWST

Massive colliding-wind binaries that host a Wolf-Rayet (WR) star present a potentially important source of dust and chemical enrichment in the interstellar medium (ISM). However, the chemical composition and survival of dust formed from such systems is not well understood. The carbon-rich WR (WC) binary WR~140 presents an ideal astrophysical laboratory for investigating these questions given its well-defined orbital period and predictable dust-formation episodes every 7.93 years around periastron passage. We present observations from our Early Release Science program (ERS1349) with the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) Medium-Resolution Spectrometer (MRS) and Imager that reveal the spectral and spatial signatures of nested circumstellar dust shells around WR~140. MIRI MRS spectroscopy of the second dust shell and Imager detections of over 17 shells formed throughout the past $\gtrsim130$ years confirm the survival of carbonaceous dust grains from WR~140 that are likely carriers of "unidentified infrared" (UIR)-band features at 6.4 and 7.7 $μ$m. The observations indicate that dust-forming WC binaries can enrich the ISM with organic compounds and carbonaceous dust.

astro-ph.SR↗

arXiv2022

Explaining the differences in massive star models from various simulations

The evolution of massive stars is the basis of several astrophysical investigations, from predicting gravitational-wave event rates to studying star-formation and stellar populations in clusters. However, uncertainties in massive star evolution present a significant challenge when accounting for these models' behaviour in stellar population studies. In this work, we present a comparison between five published sets of stellar models from the BPASS, BoOST, Geneva, MIST, and PARSEC simulations at near-solar metallicity. The different sets of stellar models have been computed using slightly different physical inputs in terms of mass-loss rates and internal mixing properties. Moreover, these models also employ various pragmatic methods to overcome the numerical difficulties that arise due to the presence of density inversions in the outer layers of stars more massive than 40 M$_\odot$. These density inversions result from the combination of inefficient convection in the low-density envelopes of massive stars and the excess of radiative luminosity to the Eddington luminosity. We find that the ionizing radiation released by the stellar populations can change by up to 18 percent, the maximum radial expansion of a star can differ between 100-1600 R$_\odot$, and the mass of the stellar remnant can vary up to 20 M$_\odot$ between the five sets of simulations. We conclude that any attempts to explain observations that rely on the use of models of stars more massive than 40 M$_\odot$ should be made with caution.

astro-ph.SR↗

arXiv2022

New Insights into the Evolution of Massive Stars and Their Effects on Our Understanding of Early Galaxies

The observable characteristics and subsequent evolution of young stellar populations is dominated by their massive stars. As our understanding of those massive stars and the factors affecting their evolution improves, so our interpretation of distant, unresolved stellar systems can also advance. As observations increasingly probe the distant Universe, and the rare low metallicity starbursts nearby, so the opportunity arises for these two fields to complement one another, and lead to an improved conception of both stars and galaxies. Here we review the current state of the art in modelling of massive star dominated stellar populations, and discuss their applications and implications for interpreting the distant Universe. Our principle findings include: - Binary evolutionary pathways must be included to understand the stellar populations in early galaxies. - Observations constraining the extreme ultraviolet spectrum of early galaxies are showing that current models are incomplete. The best current guess is that some form of accretion onto compact remnants is required. - The evolution and fates of very massive stars, of the order of 100Msun and above, may be key to fully understand aspects of early galaxies.

astro-ph.GA↗