Modeling X-ray emission line profiles from massive star winds – A review

Ignace, Richard

doi:10.1016/j.asr.2015.12.044

Cited by 11 publications

(5 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…from near R 1 , as determined from f ir line ratios of He-like ions. The line profiles are consistent with the expected morphology of X-ray lines originating from a uniformly expanding spherical wind of high X-raycontinuum optical depth [44,46]. However, when interpreting the X-ray spectrum of WR 6, one must keep in mind the uncertain nature of this object.…”

Section: Evolved Massive Starssupporting

confidence: 75%

See 1 more Smart Citation

X-ray emission of massive stars and their winds

Rauw¹

2022

Preprint

View full text Add to dashboard Cite

Most types of massive stars display X-ray emission that is strongly affected by the properties of their stellar winds. Single non-magnetic OB stars have an X-ray luminosity that scales with their bolometric luminosity and their emission is thought to arise from a distribution of wind-embedded shocks. The lack of significant short-term stochastic variability indicates that the winds consist of a large number of independent fragments. Detailed investigations of temporal variability unveiled a connection between the photosphere and the wind: well-studied O-type stars exhibit a ∼ 10% modulation of their emission on timescales consistent with their rotation period, and a few early B-type pulsators display ∼ 10% modulations of their X-ray flux with the same period as their photospheric pulsations. Unlike OB stars, their evolved descendants (Wolf-Rayet stars and Luminous Blue Variables) lack a well-defined relation between their X-ray and bolometric luminosities, and several subcategories of objects remain undetected. These properties most likely stem from the combined effects of wind optical depth and wind velocity. Magnetic OB stars display an enhanced X-ray emission which is frequently modulated by the rotation of the star. These properties are well explained by the magnetically confined wind shock model and an oblique magnetic rotator configuration. Some massive binaries display phase-dependent excess emission arising from the collision between the winds of the binary components. Yet, the majority of the massive binaries do not show evidence for such an emission, probably as a consequence of radiative cooling of the shock-heated plasma. Finally, a growing subset of the Be stars, the so-called γ Cas stars, feature an unusually hard and strong thermal X-ray emission that varies in a complicated manner over a wide range of timescales. Several scenarios have been proposed to explain these properties, but the origin of the γ Cas phenomenon remains currently one of the major unsolved puzzles in stellar X-ray astrophysics.

show abstract

Section: Evolved Massive Starssupporting

confidence: 75%

“…The resulting line profiles depend on the optical thickness and on the geometry of individual clumps [24,96,97,104,168,39]. This leads to the definition of an effective absorption coefficient [46]:…”

Section: Earthmentioning

confidence: 99%

X-ray emission of massive stars and their winds

Rauw¹

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…The observed velocity difference is likely due to the suppression of the red line wing, due to occultation effects commonly observed in stellar winds (see e.g., Ignace 2016, and references therein). The line profiles are quite symmetric, which likely indicates optically thick lines in a homologous velocity field (Ignace 2016, see their Fig. 8).…”

Section: Spectroscopymentioning

confidence: 80%

The Carnegie Supernova Project II. Observations of the intermediate luminosity red transient SNhunt120

Stritzinger,

Taddia,

Fraser

et al. 2020

Preprint

View full text Add to dashboard Cite

We present multi-wavelength observations of two gap transients followed by the Carnegie Supernova Project-II and supplemented with data obtained by a number of different programs. Here in the first of two papers, we focus on the intermediate luminosity red transient (ILRT) designated SNhunt120, while in a companion paper we examine the luminous red novae AT 2014ej. Our data set for SNhunt120 consists of an early optical discovery, estimated to be within 3 days after outburst, the subsequent optical and nearinfrared broadband followup extending over a ∼2 month period, two visual-and two near-infrared wavelength spectra, and Spitzer Space Telescope observations extending from early (+28 d) to late (+1155 d) phases. SNhunt120 resembles other ILRTs such as NGC 300-2008-OT and SN 2008S, and like these other ILRTs, SNhunt120 exhibits prevalent mid-infrared emission at both early and late phases. From the comparison of SNhunt120 and other ILRTs to electron-capture supernova simulations, we find that the current models underestimate the explosion kinetic energy and thereby produce synthetic light curves that over-estimate the luminosity. Finally, examination of pre-outburst Hubble Space Telescope images yields no progenitor detection.

show abstract

“…is stronger and resolving power is highest, asymmetrically shaped lines may be expected (e.g., Ignace 2016). Even in these cases, a Gaussian is often still sufficient to characterize the lines relative to others and to other stars on a uniform basis.…”

Section: Spectral Extraction and Fittingmentioning

confidence: 99%

Survey of X-Rays from Massive Stars Observed at High Spectral Resolution with Chandra

Pradhan,

Huenemoerder,

Ignace

et al. 2023

ApJ

View full text Add to dashboard Cite

Identifying trends between observational data and the range of physical parameters of massive stars is a critical step to the still-elusive full understanding of the source, structure, and evolution of X-ray emission from the stellar winds, requiring a substantial sample size and systematic analysis methods. As of 2022, the Chandra data archive contains 37 high-resolution spectra of O, B, and WR stars, observed with the Chandra/HETGS, and of sufficient quality to fit the continua and emission-line profiles. Using a systematic approach to the data analysis, we explore morphological trends in the line profiles (i.e., O, Ne, Mg, and Si) and find that the centroid offsets of resolved lines versus wavelength can be separated in three empirically defined groups based on the amount of line broadening and centroid offset. Using Fe xvii (15.01, 17.05 Å) and Ne x α (12.13 Å) lines, which are prevalent among the sample stars, we find a well-correlated linear trend of increasing Full Width Half Maximum with faster wind terminal velocity. The H-like/He-like total line flux ratio for strong lines displays different trends with spectral class depending on ion species. Some of the sources in our sample have peculiar properties (e.g., magnetic and γ Cas-analog stars) and we find that these sources stand out as outliers from more regular trends. Finally, our spectral analysis is presented summarily in terms of X-ray spectral energy distributions in specific luminosity for each source, including tables of line identifications and fluxes.

show abstract

Modeling X-ray emission line profiles from massive star winds – A review

Cited by 11 publications

References 76 publications

X-ray emission of massive stars and their winds

X-ray emission of massive stars and their winds

The Carnegie Supernova Project II. Observations of the intermediate luminosity red transient SNhunt120

Survey of X-Rays from Massive Stars Observed at High Spectral Resolution with Chandra

Contact Info

Product

Resources

About