scholarly journals Unveiling the structure of the progenitors of type-IIP Supernovae through multi-waveband observations

2017 ◽  
Vol 12 (S331) ◽  
pp. 17-22
Author(s):  
F. K. Sutaria ◽  
Alak Ray ◽  
Subhash Bose ◽  
Brijesh Kumar
Keyword(s):  
Mass Loss ◽  
Temporal Evolution ◽  
Mass Range ◽  
Optical Observations ◽  
Stellar Winds ◽  
Late Time ◽  
X Ray ◽  
Steep Decline ◽  
Evolutionary Paths ◽  
Comparable Mass

AbstractObservational evidence from archival, pre-explosion images, suggests that progenitors of type-IIP SNe (SNe-IIP) have 8 ⩽MP⩽ 17M⊙. However, the post-explosion temporal evolution of the event suggests that even in this mass range, the stellar evolutionary paths, the ensuing mass loss, and the eventual interaction of the supernova shock with the resulting CSM can show considerable diversity. Here we present the results from our program on multi-waveband (mainly optical) observations of SNe-IIP. Mass loss in their progenitors, with a massive and extended H-envelopes, is seen to occur via both strong stellar winds, or episodic mass ejections. Moreover, some type-IIP SNe also show unusually steep decline, characteristic of type-IIL (e.g. SN-IIP 2013ej). Our early and late-time spectrophotometry of these events shows CSM- shock interaction to varying degree among progenitors of comparable mass. Combined with X-ray data, our findings suggest that SNe-IIP progenitors can lose mass via strong stellar winds (e.g. SN2013ej, and SN2014cx), have episodic mass loss (SN2011ja), or have negligible mass loss (SN2012aw, SN2013ab).

scholarly journals What Do We Really Know About the Winds of Massive Stars?

2007 ◽  
Vol 3 (S250) ◽  
pp. 89-96
Author(s):  
D. John Hillier
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Standard Theory ◽  
Stellar Winds ◽  
X Rays ◽  
X Ray ◽  
Stellar Photosphere ◽  
Weak Winds ◽  
Ionization Balance ◽  
Loss Rates

AbstractThe standard theory of radiation driven winds has provided a useful framework to understand stellar winds arising from massive stars (O stars, Wolf-Rayet stars, and luminous blue variables). However, with new diagnostics, and advances in spectral modeling, deficiencies in our understanding of stellar winds have been thrust to the forefront of our research efforts. Spectroscopic observations and analyses have shown the importance of inhomogeneities in stellar winds, and revealed that there are fundamental discrepancies between predicted and theoretical mass-loss rates. For late O stars, spectroscopic analyses derive mass-loss rates significantly lower than predicted. For all O stars, observed X-ray fluxes are difficult to reproduce using standard shock theory, while observed X-ray profiles indicate lower mass-loss rates, the potential importance of porosity effects, and an origin surprisingly close to the stellar photosphere. In O stars with weak winds, X-rays play a crucial role in determining the ionization balance, and must be taken into account.

scholarly journals Spectral Diagnoses of Chromospheres and Winds in A-Type Stars

1993 ◽  
Vol 138 ◽  
pp. 517-527 ◽  
Author(s):  
Thierry Lanz ◽  
Ivan Hubeny
Keyword(s):  
Mass Loss ◽  
Main Sequence ◽  
Stellar Winds ◽  
X Ray ◽  
Upper Limits ◽  
Radiative Diffusion ◽  
Increased Sensitivity ◽  
Chemical Anomalies ◽  
Set Up ◽  
Near Future

AbstractSo far, neither chromospheres nor stellar winds have been directly detected in main-sequence A stars. While radiative diffusion requires extremely weak stellar winds to reproduce chemical anomalies (10−15 to 10−12M⊙yr−1), two independent direct searches for mass loss set up upper limits to 10−10 M⊙yr−1, which is still several orders of magnitude higher. We discuss some new recent possibilities to detect chromospheres which arise thanks to new NLTE model atmospheres. In the near future, some progress is also expected from new observations of Lyman α with HST and from the increased sensitivity of ROSAT in the X-ray domain.

scholarly journals Colliding stellar wind modelling of the X-ray emission from WR 140

2020 ◽  
Vol 500 (4) ◽  
pp. 4837-4848
Author(s):  
Svetozar A Zhekov
Keyword(s):  
Mass Loss ◽  
Effective Mass ◽  
Stellar Wind ◽  
Mass Loss Rate ◽  
Emission Measure ◽  
Strong Line ◽  
Stellar Winds ◽  
Line Profiles ◽  
X Ray ◽  
Binary Orbit

ABSTRACT We modelled the Chandra and Rossi X-ray Timing Explorer X-ray spectra of the massive binary WR 140 in the framework of the standard colliding stellar wind (CSW) picture. Models with partial electron heating at the shock fronts are a better representation of the X-ray data than those with complete temperature equalization. Emission measure of the X-ray plasma in the CSW region exhibits a considerable decrease at orbital phases near periastron. This is equivalent to variable effective mass-loss rates over the binary orbit. At orbital phases near periastron, a considerable X-ray absorption in excess to that from the stellar winds in WR 140 is present. The standard CSW model provides line profiles that in general do not match well the observed line profiles of the strong line features in the X-ray spectrum of WR 140. The variable effective mass-loss rate could be understood qualitatively in CSW picture of clumpy stellar winds where clumps are efficiently dissolved in the CSW region near apastron but not at periastron. However, future development of CSW models with non-spherically symmetric stellar winds might be needed to get a better correspondence between theory and observations.

scholarly journals X-rays from colliding winds in massive binaries

2016 ◽  
Vol 12 (S329) ◽  
pp. 359-360
Author(s):  
Yaël Nazé ◽  
Gregor Rauw
Keyword(s):  
High Resolution ◽  
Mass Loss ◽  
Strong Shock ◽  
Stellar Mass ◽  
Stellar Winds ◽  
X Rays ◽  
Current Generation ◽  
X Ray ◽  
Colliding Winds

AbstractIn a massive binary, the strong shock between the stellar winds may lead to the generation of bright X-ray emission. While this phenomenon was detected decades ago, the detailed study of this emission was only made possible by the current generation of X-ray observatories. Through dedicated monitoring and observations at high resolution, unprecedented information was revealed, putting strong constraints on the amount and structure of stellar mass-loss.

scholarly journals The Influences of Stellar Activity on Planetary Atmospheres

2016 ◽  
Vol 12 (S328) ◽  
pp. 168-179
Author(s):  
Colin P. Johnstone
Keyword(s):  
Mass Loss ◽  
Planetary Atmospheres ◽  
Time Dependent ◽  
Stellar Winds ◽  
Additional Mass ◽  
Stellar Activity ◽  
X Ray

AbstractOn evolutionary timescales, the atmospheres of planets evolve due to interactions with the planet's surface and with the planet's host star. Stellar X-ray and EUV (=’XUV’) radiation is absorbed high in the atmosphere, driving photochemistry, heating the gas, and causing atmospheric expansion and mass loss. Atmospheres can interact strongly with the stellar winds, leading to additional mass loss. In this review, I summarise some of the ways in which stellar output can influence the atmospheres of planets. I will discuss the importance of simultaneously understanding the evolution of the star's output and the time dependent properties of the planet's atmosphere.

scholarly journals Radio Observations of Massive OB Stars

1991 ◽  
Vol 143 ◽  
pp. 315-315 ◽  
Author(s):  
Ian D. Howarth ◽  
Alexander Brown
Keyword(s):  
Mass Loss ◽  
Main Sequence ◽  
Thermal Emission ◽  
Stellar Winds ◽  
X Ray ◽  
Ob Stars ◽  
Hydrogen Recombination ◽  
Flux Limit ◽  
Model Independent ◽  
Loss Rates

The mass-loss rates of O stars and B supergiants are of interest because of their influence on the evolution of these massive stars (among other matters). In principle, the ‘safest’ (i.e. most model-independent) method of determining M is to measure the free-free emission from stellar winds at radio wavelengths. This method is complicated, however, by the existence of poorly understood non-thermal emission in some stars, and by the possibility of hydrogen recombination in the winds of B supergiants.We are in the process of carrying out a VLA survey of OB stars, initially at 3.5cm, to a flux limit of ~0.1mJy. Because all our targets should have thermal emission at detectable levels (based on mass-loss rates from Howarth & Prinja 1989 and terminal velocities from Prinja, Barlow & Howarth 1990), the survey is yielding an unbiassed estimate of the frequency of non-thermal emission. The improved sensitivity of our survey over earlier work defines the log M – log L relationship much more precisely than was previously possible, over a large range in luminosities; and allows us to make definitive statements on recombination in B supergiant winds. Our sample includes the first radio detections of an OC star, of a massive X-ray binary, and of thermal emission from a main-sequence star.

scholarly journals Accretion from Stellar Winds

1988 ◽  
Vol 103 ◽  
pp. 149-160
Author(s):  
Mario Livio
Keyword(s):  
Angular Momentum ◽  
Inhomogeneous Medium ◽  
Accretion Disk ◽  
Stellar Wind ◽  
Optical Observations ◽  
Stellar Winds ◽  
X Ray ◽  
Disk Formation ◽  
X Ray Binaries

AbstractRecent calculations have demonstrated that accretion from a stellar wind is very probably unsteady. The average rate of accretion of angular momentum is lower by about a factor 5 than the rate at which angular momentum is deposited into the Bondi-Hoyle accretion cylinder. This makes disk formation from wind accretion very difficult, in particular in the case of massive x-ray binaries. A combination of x-ray, uv and optical observations of symbiotic and related systems, as well as spin-up information on x-ray binaries, can be used to determine whether an accretion disk does form. Such observations can provide us with valuable information on the process of accretion from an inhomogeneous medium.

scholarly journals X-ray Shaping of Planetary Nebulae

2018 ◽  
Author(s):  
Martin A Guerrero
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Essential Role ◽  
Planetary Nebulae ◽  
Stellar Winds ◽  
Physical Processes ◽  
X Ray ◽  
Hot Gas ◽  
Energy And Momentum ◽  
Central Stars

The stellar winds of the central stars of planetary nebulae play an essential role in planetary nebulae shaping. In the interacting stellar winds model, the fast stellar wind injects energy and momentum which are transfered to the nebular envelope through an X-ray-emitting hot bubble. Together with other physical processes, such as the ionization of the nebular envelope, the asymmetrical mass-loss in the AGB, and the action of collimated outflows and magnetic fields, the presurized hot gas determines the expansion and evolution of planetary nebulae. \emph{Chandra} and \emph{XMM-Newton} have provided us with detailed information of this hot gas. Here in this talk I will review our current understanding of the effects of the fast stellar wind in the shaping and evolution of planetary nebulae and give some hints of the promissing future of this research.

scholarly journals Circumstellar Medium Constraints on the Environment of Two Nearby Type Ia Supernovae: SN 2017cbv and SN 2020nlb

2021 ◽  
Vol 922 (1) ◽  
pp. 21
Author(s):  
D. J. Sand ◽  
S. K. Sarbadhicary ◽  
C. Pellegrino ◽  
K. Misra ◽  
R. Dastidar ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Loss Rate ◽  
Full Range ◽  
Type Ia Supernovae ◽  
Constant Density ◽  
Late Time ◽  
X Ray ◽  
Inverse Compton ◽  
Type Ia ◽  
Ia Supernovae

Abstract We present deep Chandra X-ray observations of two nearby Type Ia supernovae, SN 2017cbv and SN 2020nlb, which reveal no X-ray emission down to a luminosity L X ≲ 5.3 × 1037 and ≲ 5.4 × 1037 erg s−1 (0.3–10 keV), respectively, at ∼16–18 days after the explosion. With these limits, we constrain the pre-explosion mass-loss rate of the progenitor system to be M ̇ < 7.2 × 10−9 and < 9.7 × 10−9 M ⊙ yr−1 for each (at a wind velocity v w = 100 km s−1 and a radius of R ≈ 1016 cm), assuming any X-ray emission would originate from inverse Compton emission from optical photons upscattered by the supernova shock. If the supernova environment was a constant-density medium, we would find a number density limit of n CSM < 36 and < 65 cm−3, respectively. These X-ray limits rule out all plausible symbiotic progenitor systems, as well as large swathes of parameter space associated with the single degenerate scenario, such as mass loss at the outer Lagrange point and accretion winds. We also present late-time optical spectroscopy of SN 2020nlb, and set strong limits on any swept up hydrogen (L Hα < 2.7 × 1037 erg s−1) and helium (L He,λ6678 < 2.7 × 1037 erg s−1) from a nondegenerate companion, corresponding to M H ≲ 0.7–2 × 10−3 M ⊙ and M He ≲ 4 × 10−3 M ⊙. Radio observations of SN 2020nlb at 14.6 days after explosion also yield a non-detection, ruling out most plausible symbiotic progenitor systems. While we have doubled the sample of normal Type Ia supernovae with deep X-ray limits, more observations are needed to sample the full range of luminosities and subtypes of these explosions, and set statistical constraints on their circumbinary environments.

scholarly journals Very massive stars: a metallicity-dependent upper-mass limit, slow winds, and the self-enrichment of globular clusters

2018 ◽  
Vol 615 ◽  
pp. A119 ◽  
Author(s):  
Jorick S. Vink
Keyword(s):  
Monte Carlo ◽  
Star Formation ◽  
Mass Loss ◽  
Globular Clusters ◽  
Gamma Ray ◽  
Massive Stars ◽  
Mass Range ◽  
Stellar Winds ◽  
Mass Limit ◽  
Stellar Mergers

One of the key questions in Astrophysics concerns the issue of whether there exists an upper-mass limit to stars, and if so, what physical mechanism sets this limit? The answer to this question might also determine if the upper-mass limit is metallicity (Z) dependent. We argue that mass loss by radiation-driven winds mediated by line opacity is one of the prime candidates setting the upper-mass limit. We present mass-loss predictions (Ṁwind) from Monte Carlo radiative transfer models for relatively cool (Teff = 15 kK) very inflated massive stars (VMS) with large Eddington Γ factors in the mass range 102–103 M⊙ as a function of metallicity down to 1/100 Z∕Z⊙. We employed a hydrodynamic version of our Monte Carlo method, allowing us to predict the rate of mass loss (Ṁwind) and the terminal wind velocity (v∞) simultaneously. Interestingly, we find wind terminal velocities (v∞) that are low (100–500 km s−1) over a wide Z-range, and we propose that the slow winds from VMS are an important source of self-enrichment in globular clusters. We also find mass-loss rates (Ṁwind), exceeding the typical mass-accretion rate (Ṁaccr) of 10−3 M⊙ yr−1 during massive-star formation. We have expressed our mass-loss predictions as a function of mass and Z, finding log Ṁ = −9.13 + 2.1 log(M∕M⊙) + 0.74 log(Z∕Z⊙) (M⊙∕yr). Even if stellar winds do not directly halt & reverse mass accretion during star formation, if the most massive stars form by stellar mergers, stellar wind mass loss may dominate over the rate at which stellar growth takes place. We therefore argue that the upper-mass limit is effectively Z-dependent due to the nature of radiation-driven winds. This has dramatic consequences for the most luminous supernovae, gamma-ray bursts, and other black hole formation scenarios at different Cosmic epochs.

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