Stellar winds
Reading a stellar wind
A dark blue trough and a bright red wing trace gas around a star. Follow the photons, learn the transfer, then test the assumptions against real ultraviolet spectra.
L1
How starlight pushes a stellar wind
Resonant atoms receive momentum from light. Follow blue absorption and scattered emission to see how photons interact with an expanding stellar wind.
L1
How much momentum can light carry?
Calculate photon recoil, wind momentum and mechanical power, keeping single scattering, repeated interactions and photon tiring distinct.
L2
Resonance surfaces in an accelerating wind
Derive the projected gradient, Sobolev optical depth and scattering source, then calculate one stellar-disk ray and its contribution to a wind spectrum.
L3
What can one wind line determine?
Infer from saved integer photons, derive the mass-flow and ion-opacity degeneracy, and test a proper two-parameter prior with independent repetitions.
L3
Replaying the IUE ultraviolet spectra of P Cygni
Decode complete native IUE orders, retain quality gaps and continuum choices, then recompute a conditional isolated-line comparison.
L4
Clumps, velocity gaps and mass loss
Follow line instability into microclumping and velocity porosity, then replay the Brands 2025 tables without confusing model degeneracy with stellar trends.
Follow the flow and change the collecting aperture
Sources and calculation scope
- Owocki2014, Theory of Winds from Hot, Luminous Massive Stars
Pinned v1; section2 for CAK/Sobolev steady winds and sections3.1–3.4 for line instability, clumping, porosity and velocity gaps. Linked theory source; original is not redistributed.
- Lamers, Cerruti-Sola & Perinotto1987, the SEI line-profile method
ApJ314,726, sectionsII–V and equations4–10/14–19. Our local escape singlet and fixed-source finite-width test retain their separate approximations; no complete SEI/non-LTE solver is claimed.
- IUE NEWSIPS manual, high-dispersion MXHI format
Native17-field binary rows, padded768-element vectors, one-based STARTPIX, vacuum heliocentric wavelengths, ABS_CAL physical units and FN noise.
- IUE data-analysis FAQ
Questions13–15: reject nonzero quality flags for quantitative use; high-dispersion cosmic rays are not automatically removed; exposure alone does not define a noise weight.
- NIST magnesium energy levels
MgII level wavenumbers35760.848/35669.298per centimetre yield laboratory vacuum2796.3543/2803.5315Angstrom. Laboratory rest and stellar systemic velocity are distinct.
- MAST original mission data use
Original NASA/ESA/UK IUE public mission products; fixed names, complete bytes and SHA remain in the standalone package with mission/STScI/MAST attribution.
- Brands, Backs, de Koter et al.2025, X-Shooting ULLYSES XII
Pinned v1; sections3/5.3–5.5, Figures1/4/7 and Tables7/8. Twenty-five LMC O-type targets yield24parameter sets. Their model-conditional population/fitness results are external, not P Cygni measurements.
- Brands2025 Zenodo15044512 v1.1.1 tables
CC-BY4 complete optical+UV and optical-only24-row tables plus original readme. FASTWIND10.6.0 is proprietary; no model archive or engine is redistributed.
- Standalone stellar-wind scientific reproduction
Original small data, independent transfer/photon/force/finite-width references,197producer checks and a proper synthetic Poisson exercise. Fixed truths and prior-averaged coverage remain separate.