Radio view of a broad-line Type Ic supernova ASASSN-16fp

ABSTRACT We present extensive radio observations of a Type Ic supernova, ASASSN-16fp. Our data represent the lowest frequency observations of the supernova beyond 1000 d with a frequency range of 0.33–25 GHz and a temporal range of ∼8–1136 d post-explosion. The observations are best represented by a model of synchrotron emission from a shocked circumstellar shell initially suppressed by synchrotron self-absorption. Assuming equipartition of energy between relativistic particles and magnetic fields, we estimate the velocity and radius of the blast wave to be $v$ ∼ 0.15c and r ∼ 3.4 × 1015 cm, respectively, at t0 ∼ 8 d post-explosion. We infer the total internal energy of the radio-emitting material evolves as E ∼ 0.37 × 1047 (t/t0)0.65 erg. We determine the mass-loss rate of the progenitor star to be $\dot{M} \sim (0.4\!-\!3.2) \times 10^{-5}\, \mathrm{M}_{\odot }\, \rm yr^{-1}$ at various epochs post-explosion, consistent with the mass-loss rate of Galactic Wolf–Rayet stars. The radio light curves and spectra show a signature of density enhancement in the circumstellar medium at a radius of ∼1.10 × 1016 cm from the explosion centre.

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On the evolutionary status and instability mechanism of the Luminous Blue Variables (LBV)

International Astronomical Union Colloquium ◽

10.1017/s0252921100004243 ◽

1989 ◽

Vol 113 ◽

pp. 15-26

Author(s):

André Maeder

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Light Curves ◽

Evolutionary Status ◽

Average Mass ◽

Luminous Blue Variables ◽

Ir Sources ◽

Order Of Magnitude ◽

Lower Luminosity

AbstractVarious evolutionary sequences leading to LBV are examined. The sequence O-Of-LBV-WR-SN is well supported by the models; some LBV with relatively lower luminosity may turn into OH/IR sources. The overall duration of the LBV phase depends mainly on the average mass loss rate; for <Ṁ> = 10−3M⊙y−1, it lasts about 104y.Very massive stars undergo, when they reach logTeff= 3.9, strong departure from hydrostatic equilibrium due to supra-Eddington luminosities at some depth in the outer layers. This results in heavy mass loss, as the growth rate of the instability is very fast. We suggest that the amount of mass ejected in a shell episode is mainly determined by the mass of such a layer that its thermal adjustment timescale is within an order of magnitude of the stellar dynamical timescale. Simulations of B-light curves due to shell ejections by LBV are performed and some sensitive properties are identified.

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The RCB Stars and their Circumstellar Material

International Astronomical Union Colloquium ◽

10.1017/s0252921100090709 ◽

1985 ◽

Vol 87 ◽

pp. 151-166

Author(s):

M.W. Feast

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Circumstellar Dust ◽

Average Mass ◽

Circumstellar Material ◽

Carbon Particles ◽

Circumstellar Shell

RCB stars are surrounded by circumstellar dust and gas moving radially outwards at ~200 km/sec. The circumstellar shell is made up of discrete puffs of matter, a typical puff occupying an area ~0.03 of a complete shell. On the average puffs are ejected about once every 40 days (comparable with the known pulsation periods of RCB stars). The reddening law of the dust indicates that it is composed of small carbon particles (radii ~100A). The flux from the shell at L typically varies by 1 to 3 mags over periods of 1000-2000 days. The average mass loss rate is ~10−6MO/yr.

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OH masers in oxygen-rich late-type stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900222626 ◽

2002 ◽

Vol 206 ◽

pp. 319-322

Author(s):

Sandra Etoka ◽

A.M. Le Squeren

Keyword(s):

Mass Loss ◽

Radio Telescope ◽

Loss Rate ◽

Mass Loss Rate ◽

Monitoring Programme ◽

Late Type ◽

Wide Range ◽

Ir Stars ◽

Circumstellar Shell

We present here some noteworthy results of two related studies on oxygen-rich late type stars. The aim of this work was to study the OH circumstellar shell properties in terms of evolution. These studies are based on an OH monitoring programme carried out with the Nançay Radio Telescope. The first study concerns seven Miras distributed along the colour-colour diagram. They were observed at two or three different epochs covering one to seven cycles over a period from 1980 to 1995 at 1612, 1667 and 1665 MHz in both circular polarizations. The second study concerns thirty objects covering a wide range of mass loss rate from Miras to OH/IR stars. They were observed in 1994 at 1665 & 1667 MHz in both circular polarizations.

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Five New Hot Jupiter Transits Investigated with Swift-UVOT

The Astronomical Journal ◽

10.3847/1538-3881/ac2c67 ◽

2021 ◽

Vol 162 (6) ◽

pp. 287

Author(s):

Lia Corrales ◽

Sasikrishna Ravi ◽

George W. King ◽

Erin May ◽

Emily Rauscher ◽

...

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Equilibrium Temperature ◽

Light Curves ◽

X Ray ◽

Hot Jupiters ◽

Upper Limits ◽

Marginal Detection ◽

Optical Radius

Abstract Short-wavelength exoplanet transit measurements have been used to probe mass loss in exoplanet atmospheres. We present the Swift-UVOT transit light curves for five hot Jupiters orbiting UV-bright F-type stars: XO-3, KELT-3, WASP-3, WASP-62, and HAT-P-6. We report one positive transit detection of XO-3b and one marginal detection of KELT-3b. We place upper limits on the remaining three transit depths. The planetary radii derived from the NUV transit depths of both potential detections are 50%–100% larger than their optical radius measurements. We examine the ratio R NUV/R opt for trends as a function of estimated mass-loss rate, which we derive from X-ray luminosity obtained from the Swift-XRT or, in the case of WASP-62, XMM-Newton. We find no correlation between the energy-limited photoevaporative mass-loss rate and the R NUV/R opt ratio. We also search for trends based on the equilibrium temperature of the hot Jupiters. We find a possible indication of a transition in the R NUV/R opt ratio around T eq = 1700 K, analogous to the trends found for NIR water features in transmission spectra. This might be explained by the formation of extended cloud decks with silicate particles ≤1 μm. We demonstrate that the Swift-UVOT filters could be sensitive to absorption from aerosols in exoplanet atmospheres.

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The Maser Strength of OH/IR Stars, the Evolution of Mass loss and the Formation of a Planetary Nebula

Symposium - International Astronomical Union ◽

10.1017/s0074180900094304 ◽

1983 ◽

Vol 103 ◽

pp. 530-530

Author(s):

B. Baud ◽

H. J. Habing

Keyword(s):

Mass Loss ◽

Planetary Nebula ◽

Loss Rate ◽

Large Range ◽

Mass Loss Rate ◽

Asymptotic Giant Branch ◽

Expansion Velocity ◽

Simple Modification ◽

Ir Stars ◽

Circumstellar Shell

From observations we find that the OH luminosity LOH of an OH/IR star increases with R2, where R is the size of the masing region. From this correlation we deduce that the mass loss rate M, the expansion velocity ve and LOH are related by LOH ~(M/ve)2. Next we consider the large range that is observed in LOH and the steep OH luminosity distribution for OH/IR stars. Both facts can be explained by the postulate that these objects undergo accelerated mass loss, and thus steadily increase their OH luminosity. We propose that OH/IR stars are at the extreme end of the Asymptotic Giant Branch and that many of them are in the process of blowing off their entire envelope in a superwind phase. Their mass loss rate during this superwind, as deduced from OH observations of the circumstellar shell, is given by a simple modification of the Reimers equation. This modification connects the superwind continuously to the Reimers wind and it provides observational evidence for the formation of a planetary nebula.

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