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…
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…
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…
Revisiting Attenuation Curves: The Case of NGC 3351
Grebel, Eva K.; Östlin, Göran; Smith, Linda J. +14 more
Multiwavelength images from the far-UV (∼0.15 µm) to the submillimeter of the central region of the galaxy NGC 3351 are analyzed to constrain its stellar populations and dust attenuation. Despite hosting a ∼1 kpc circumnuclear starburst ring, NGC 3351 deviates from the IRX-β relation, the relation between the infrared-to-UV luminosity ratio …
New Hydrodynamic Solutions for Line-driven Winds of Hot Massive Stars Using the Lambert W-function
Hillier, D. J.; Najarro, F.; Gormaz-Matamala, A. C. +3 more
Hot massive stars present strong stellar winds that are driven by absorption, scattering, and reemission of photons by the ions of the atmosphere (line-driven winds). A better comprehension of this phenomenon, and a more accurate calculation of hydrodynamics and radiative acceleration, is Required to reduce the number of free parameters in spectra…
A Multi-Observing Technique Study of the Dynamical Evolution of the Viscous Disk around the Be Star ω CMa
Rivinius, Thomas; Baade, Dietrich; Carciofi, Alex C. +3 more
The observed emission lines of Be stars originate from a circumstellar Keplerian disk, which is generally well explained by the viscous decretion disk model. In an earlier work we performed modeling of the full light curve of the bright Be star ω CMa with the 1D time-dependent hydrodynamic code SINGLEBE and the Monte Carlo radiative transfer code …
The First Dynamical Mass Determination of a Nitrogen-rich Wolf-Rayet Star Using a Combined Visual and Spectroscopic Orbit
Monnier, John D.; Lanthermann, Cyprien; Anugu, Narsireddy +11 more
We present the first visual orbit for the nitrogen-rich Wolf-Rayet binary, WR 133 (WN5o + O9I), based on observations made with the CHARA Array and the MIRC-X combiner. This orbit represents the first visual orbit for a WN star and only the third Wolf-Rayet star with a visual orbit. The orbit has a period of 112.8 days, a moderate eccentricity of …
ν Gem: A Hierarchical Triple System with an Outer Be Star
Gies, Douglas R.; Klement, Robert; Rivinius, Thomas +17 more
Time series of spectroscopic, speckle-interferometric, and optical long-baseline-interferometric observations confirm that ν Gem is a hierarchical triple system. It consists of an inner binary composed of two B-type stars and an outer classical Be star. Several photospheric spectral lines of the inner components were disentangled, revealing two st…
Mrk 1239: a Type-2 Counterpart of Narrow-line Seyfert-1?
Zhou, Hongyan; Ji, Tuo; Shi, Xiheng +10 more
We present new spectrophotometric and spectropolarimetric observations of Mrk 1239, one of the 8 prototypes that defines type-1 narrow-line Seyfert galaxies (NLS1s). Unlike the other typical NLS1s though, a high degree of polarization (P ∼ 5.6%) and red optical-IR (g-W4 = 12.35) colors suggest that Mrk 1239 is more similar to type-2 act…