Search Publications
A Comparative Study of Atmospheric Chemistry with VULCAN
Heng, Kevin; Tsai, Shang-Min; Kitzmann, Daniel +4 more
We present an update of the open-source photochemical kinetics code VULCAN to include C-H-N-O-S networks and photochemistry. The additional new features are advection transport, condensation, various boundary conditions, and temperature-dependent UV cross sections. First, we validate our photochemical model for hot Jupiter atmospheres by performin…
The Detection and Characterization of Be+sdO Binaries from HST/STIS FUV Spectroscopy
Gies, Douglas R.; Lester, Kathryn V.; Wang, Luqian +4 more
The B emission-line stars are rapid rotators that were probably spun up by mass and angular momentum accretion through mass transfer in an interacting binary. Mass transfer will strip the donor star of its envelope to create a small and hot subdwarf remnant. Here we report on Hubble Space Telescope/STIS far-ultraviolet spectroscopy of a sample of …
Milky Way Mid-Infrared Spitzer Spectroscopic Extinction Curves: Continuum and Silicate Features
Gordon, Karl D.; Hines, Dean C.; Bouwman, Jeroen +7 more
We measured the mid-infrared (MIR) extinction using Spitzer photometry and spectroscopy (3.6-37 µm) for a sample of Milky Way sight lines (mostly) having measured ultraviolet extinction curves. We used the pair method to determine the MIR extinction that we then fit with a power law for the continuum and modified Drude profiles for the silic…
How to Identify Exoplanet Surfaces Using Atmospheric Trace Species in Hydrogen-dominated Atmospheres
Fortney, Jonathan J.; Moses, Julianne I.; Zhang, Xi +1 more
Sub-Neptunes (Rp ~ 1.25-4 REarth) remain the most commonly detected exoplanets to date. However, it remains difficult for observations to tell whether these intermediate-sized exoplanets have surfaces and where their surfaces are located. Here we propose that the abundances of trace species in the visible atmospheres of these…
Empirical mass-loss rates and clumping properties of Galactic early-type O supergiants
Puls, J.; de Koter, A.; Sana, H. +7 more
Aims: We investigate the impact of optically thick clumping on spectroscopic stellar wind diagnostics in O supergiants and constrain wind parameters associated with porosity in velocity space. This is the first time the effects of optically thick clumping have been investigated for a sample of massive hot stars, using models which include a f…
Evidence for disequilibrium chemistry from vertical mixing in hot Jupiter atmospheres. A comprehensive survey of transiting close-in gas giant exoplanets with warm-Spitzer/IRAC
Deming, Drake; Burrows, Adam; Fortney, Jonathan J. +10 more
Aims: We present a large atmospheric study of 49 gas giant exoplanets using infrared transmission photometry with Spitzer/IRAC at 3.6 and 4.5 µm.
Methods: We uniformly analyze 70 photometric light curves of 33 transiting planets using our custom pipeline, which implements pixel level decorrelation. Augmenting our sample with 16 pre…
The Tarantula Massive Binary Monitoring. V. R 144: a wind-eclipsing binary with a total mass ≳140 M⊙
Howarth, I. D.; Crowther, P. A.; de Mink, S. E. +21 more
Context. The evolution of the most massive stars and their upper-mass limit remain insufficiently constrained. Very massive stars are characterized by powerful winds and spectroscopically appear as hydrogen-rich Wolf-Rayet (WR) stars on the main sequence. R 144 is the visually brightest WR star in the Large Magellanic Cloud. R 144 was reported to …
MPS-ATLAS: A fast all-in-one code for synthesising stellar spectra
Solanki, S. K.; Shapiro, A. I.; Tagirov, R. V. +6 more
Context. Stellar spectral synthesis is essential for various applications, ranging from determining stellar parameters to comprehensive stellar variability calculations. New observational resources as well as advanced stellar atmosphere modelling, taking three dimensional effects from radiative magnetohydrodynamics calculations into account, requi…
New mass-loss rates of B supergiants from global wind models
Krtička, J.; Kubát, J.; Krtičková, I.
Massive stars lose a significant fraction of mass during their evolution. However, the corresponding mass-loss rates are rather uncertain, especially for evolved stars. To improve this, we calculated global line-driven wind models for Galactic B supergiants. Our models predict radial wind structure and particularly the mass-loss rates and terminal…
The Be Star 66 Ophiuchi: 60 Years of Disk Evolution
Carciofi, A. C.; Mota, B. C.; Jones, C. E. +5 more
We use a time-dependent hydrodynamic code and a non-LTE Monte Carlo code to model disk dissipation for the Be star 66 Ophiuchi. We compiled 63 years of observations from 1957 to 2020 to encompass the complete history of the growth and subsequent dissipation of the star's disk. Our models are constrained by new and archival photometry, spectroscopy…