Constraints on Wind Structure from the Infrared and Radio Continuum of Hot Stars

1998 ◽  
pp. 254-257
Author(s):  
Mark C. Runacres ◽  
Ronny Blomme
Keyword(s):  
Radio Continuum ◽  
Hot Stars ◽  
Wind Structure

scholarly journals X-ray spectroscopy of massive stellar winds: previous and ongoing observations of the hot star ζ Pup

2018 ◽  
Vol 14 (S346) ◽  
pp. 88-92
Author(s):  
N. Miller ◽  
W. Waldron ◽  
J. Nichols ◽  
D. Huenemoerder ◽  
M. Dahmer ◽  
...  
Keyword(s):  
Emission Line ◽  
Line Profile ◽  
Stellar Wind ◽  
Galactic Evolution ◽  
Stellar Winds ◽  
Hot Stars ◽  
X Ray ◽  
Wind Structure ◽  
Important Impact ◽  
Emission Line Profile

AbstractThe stellar winds of hot stars have an important impact on both stellar and galactic evolution, yet their structure and internal processes are not fully understood in detail. One of the best nearby laboratories for studying such massive stellar winds is the O4I(n)fp star ζ Pup. After briefly discussing existing X-ray observations from Chandra and XMM, we present a simulation of X-ray emission line profile measurements for the upcoming 840 kilosecond Chandra HETGS observation. This simulation indicates that the increased S/N of this new observation will allow several major steps forward in the understanding of massive stellar winds. By measuring X-ray emission line strengths and profiles, we should be able to differentiate between various stellar wind models and map the entire wind structure in temperature and density. This legacy X-ray spectrum of ζ Pup will be a useful benchmark for future X-ray missions.

scholarly journals e-MERLIN Radio Continuum Measurements of OB Star Winds in CYG OB2

2015 ◽  
Vol 12 (S316) ◽  
pp. 169-170
Author(s):  
Jack Morford ◽  
Raman Prinja ◽  
Danielle Fenech
Keyword(s):  
Mass Loss ◽  
Massive Star ◽  
Massive Stars ◽  
Radial Distance ◽  
Radio Continuum ◽  
Hot Stars ◽  
Cluster Evolution ◽  
First Results ◽  
Formation And Evolution ◽  
Crucial Parameter

AbstractHere, we report on the first results from the e-MERLIN Cyg OB2 Radio Survey (COBRaS), which is designed to exploit e-MERLIN’s enhanced capabilities to conduct deep-field mapping of the tremendously rich Cyg OB2 association. The project aims to deliver the most detailed radio census of the most massive OB association in the northern hemisphere. There exists considerable evidence for clumping in the winds of hot stars, which has hugely important consequences for mass-loss determinations. The amount of mass lost from a massive star is a crucial parameter required for stellar and cluster evolution models that are paramount to our understanding of the formation and evolution of massive star clusters. Presenting some of the first 20cm (L band) detections of massive stars in Cyg OB2, both accurate mass-loss determinations and constraints upon clumping within their winds are made. These data substantially increase the observational detections of the outer wind of massive stars and in combination with other observations at different wavelengths, COBRaS will greatly advance our knowledge of clumping as a function of radial distance around massive stars.

Wind inhibition in HMXBs: the effect of clumping and implications for X-ray luminosity

2018 ◽  
Vol 14 (S346) ◽  
pp. 28-33
Author(s):  
Jiří Krtička ◽  
Jiří Kubát ◽  
Iva Krtičková
Keyword(s):  
Stellar Wind ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Small Scale ◽  
Radiative Force ◽  
Ionization State ◽  
Hot Stars ◽  
X Ray ◽  
Wind Structure ◽  
Absorption Of Light

AbstractWinds of hot stars are driven by the radiative force due to absorption of light in the lines of heavier elements. Consequently, the mass-loss rate and the wind velocity depend on the ionization state of the wind. As a result of this, there is a feedback between the ionizing X-ray source and the stellar wind in HMXBs powered by wind accretion. We study the influence of the small-scale wind structure (clumping) on this feedback using our NLTE hydrodynamical wind models. We find that clumping weakens the effect of X-ray irradiation. Moreover, we show that the observed X-ray luminosities of HMXBs can not be explained by wind accretion scenario without introducing the X-ray feedback. Taking into account the feedback, the observed and estimated X-ray luminosities nicely agree. We identify two cases of X-ray feedback with low and high X-ray luminosities that can explain the dichotomy between SFXTs and sgXBs.

scholarly journals Light variations due to the line-driven wind instability and wind blanketing in O stars

2018 ◽  
Vol 617 ◽  
pp. A121 ◽  
Author(s):  
J. Krtička ◽  
A. Feldmeier
Keyword(s):  
Light Curve ◽  
Radiative Flux ◽  
Light Curves ◽  
Hot Stars ◽  
Photometric Variability ◽  
Hydrodynamic Simulations ◽  
Wind Structure ◽  
Stellar Photosphere ◽  
Wind Instability ◽  
Light Variability

A small fraction of the radiative flux emitted by hot stars is absorbed by their winds and redistributed towards longer wavelengths. This effect, which leads also to the heating of the stellar photosphere, is termed wind blanketing. For stars with variable winds, the effect of wind blanketing may lead to the photometric variability. We have studied the consequences of line driven wind instability and wind blanketing for the light variability of O stars. We combined the results of wind hydrodynamic simulations and of global wind models to predict the light variability of hot stars due to the wind blanketing and instability. The wind instability causes stochastic light variability with amplitude of the order of tens of millimagnitudes and a typical timescale of the order of hours for spatially coherent wind structure. The amplitude is of the order of millimagnitudes when assuming that the wind consists of large number of independent concentric cones. The variability with such amplitude is observable using present space borne photometers. We show that the simulated light curve is similar to the light curves of O stars obtained using BRITE and CoRoT satellites.

scholarly journals Observations of deep-seated structure in the stellar winds of OB stars

1995 ◽  
Vol 10 ◽  
pp. 344-348
Author(s):  
R. K. Prinja
Keyword(s):  
Time Dependent ◽  
Stellar Winds ◽  
Line Profiles ◽  
Resolution Time ◽  
Hot Stars ◽  
Time Resolved ◽  
Ob Stars ◽  
Spectroscopic Monitoring ◽  
Wind Structure ◽  
Nonradial Pulsation

High-resolution, time-resolved spectroscopy in both optical and UV wavebands has shown that the outer layers of luminous OB stars vary on time scales of hours-days. Spectroscopic monitoring with the IUE satellite provides evidence that the stellar winds of luminous, hot stars are not smooth and steady, but are frequently disrupted by the presence of time-dependent structures. In addition, variability is often present in optical photospheric line profiles; these variations are likely due to the influence of photospheric velocity fields, especially those from one or more modes of nonradial pulsation (NRP). The process (or processes) responsible for the formation of time-dependent wind structure is (are) not known. Issues concerning potential connections between NRPs, variations at the base of the outflow, and the development of wind structure pose some of the greatest challenges to our understanding of mass-loss via radiatively driven stellar winds.

Radio Continuum Measurements of Southern Early‐Type Stars. III. Nonthermal Emission from Wolf‐Rayet Stars

1999 ◽  
Vol 518 (2) ◽  
pp. 890-900 ◽  
Author(s):  
Jessica M. Chapman ◽  
Claus Leitherer ◽  
Barbel Koribalski ◽  
Roderick Bouter ◽  
Michelle Storey
Keyword(s):  
Radio Continuum ◽  
Early Type ◽  
Nonthermal Emission ◽  
Early Type Stars

Simulated synchrotron emission for the Tycho’s supernova remnants: an asymmetric initial mass model

2020 ◽  
Vol 494 (2) ◽  
pp. 1531-1538
Author(s):  
A Moranchel-Basurto ◽  
P F Velázquez ◽  
G Ares de Parga ◽  
E M Reynoso ◽  
E M Schneiter ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Brightness Distribution ◽  
Radio Continuum ◽  
Initial Mass ◽  
Continuum Emission ◽  
Synchrotron Emission ◽  
Mass Model ◽  
Mhd Simulations ◽  
Tycho’S Snr ◽  
Good Agreement

ABSTRACT We have performed 3D magnetohydrodynamics (MHD) numerical simulations with the aim of exploring the scenario in which the initial mass distribution of a supernova (SN) explosion is anisotropic. The purpose is to analyse if this scenario can also explain the radio-continuum emission and the expansion observed in young supernova remnants (SNRs). To study the expansion, synthetic polarized synchrotron emission maps were computed from the MHD simulations. We found a good agreement (under a number of assumptions) between this expansion study and previous observational results applied to Tycho’s SNR, which represents a good example of asymmetric young SNRs. Additionally, both the observed morphology and the brightness distribution are qualitatively reproduced.

scholarly journals The Radio Continuum of the Metal‐deficient Blue Compact Dwarf Galaxy SBS 0335−052

2004 ◽  
Vol 606 (2) ◽  
pp. 853-861 ◽  
Author(s):  
Leslie K. Hunt ◽  
Kristy K. Dyer ◽  
Trinh X. Thuan ◽  
James S. Ulvestad
Keyword(s):  
Dwarf Galaxy ◽  
Radio Continuum ◽  
Blue Compact Dwarf Galaxy
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