scholarly journals Theoretical Aspects of Mass Loss from Late-Type Stars

1977 ◽  
Vol 42 ◽  
pp. 577-590 ◽  
Author(s):  
Ray J. Weymann
Keyword(s):  
Mass Loss ◽  
Neutral Hydrogen ◽  
Radio Radiation ◽  
Late Type ◽  
Circumstellar Envelopes ◽  
Molecular Line ◽  
Infrared Excess ◽  
Line Radiation ◽  
Stellar Radiation ◽  
Expanding Shells

Since Deutsch’s (1956) discovery that in α Herculis the displaced circumstellar absorption lines common in the spectra of late-type giants and supergiants really represented a loss of matter, the evidence that this is a very extensive and common feature among all late giants and supergiants has become very persuasive. To the extensive optical spectroscopic evidence for mass loss from these stars originally obtained by Deutsch and subsequently by others, we may now add observations of infrared excess from dust in circumstellar envelopes (Merrill 1977), radio molecular line radiation from expanding shells (Winnburg 1971), thermal and possibly 21 cm radio radiation from ionized and neutral hydrogen respectively (Smolinski et al. 1977; Zuckerman 1977) and the direct photographs of the envelope of α Ori in the light of one of the potassium resonance lines from scattered stellar radiation (Bernat et al. 1977).

scholarly journals Stellar masers, circumstellar envelopes and supernova remnants

2007 ◽  
Vol 3 (S242) ◽  
pp. 236-245
Author(s):  
Athol J. Kemball
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Supernova Remnants ◽  
Stellar Mass ◽  
Stellar Atmospheres ◽  
Late Type ◽  
Open Future ◽  
Circumstellar Envelopes ◽  
Recent Advances

AbstractThis paper reviews recent advances in the study or circumstellar masers and masers found toward supernova remnants. The review is organized by science focus area, including the astrophysics of extended stellar atmospheres, stellar mass-loss processes and outflows, late-type evolved stellar evolution, stellar maser excitation and chemistry, and the use of stellar masers as independent distance estimators. Masers toward supernova remnants are covered separately. Recent advances and open future questions in this field are explored.

scholarly journals Circumstellar spirals/shells/arcs: the message from binary stars

2016 ◽  
Vol 12 (S323) ◽  
pp. 199-206
Author(s):  
Hyosun Kim
Keyword(s):  
Mass Loss ◽  
Binary Stars ◽  
Planetary Nebula ◽  
Fossil Record ◽  
Asymptotic Giant Branch ◽  
Agb Stars ◽  
Circumstellar Envelopes ◽  
Molecular Line ◽  
The Past ◽  
Recurrent Patterns

AbstractA consensus has grown in the past few decades that binarity is key to understanding the morphological diversities of the circumstellar envelopes (CSEs) surrounding stars in the Asymptotic Giant Branch (AGB) to Planetary Nebula (PN) phase. The possible roles of binaries in their shaping have, however, yet to be confirmed. Meanwhile, recurrent patterns are often found in the CSEs of AGB stars and the outer halos of PNe, providing a fossil record of the mass loss during the AGB phase. In this regard, recent molecular line observations using interferometric facilities have revealed the spatio-kinematics of such patterns. Numerical simulations of binary interactions producing spiral-shells have been extensively developed, revealing new probes for extracting the stellar and orbital properties from these patterns. I review recent theoretical and observational investigations on the circumstellar spiral-shell patterns and discuss their implications in linking binary properties to the asymmetric ejection events in the post-AGB phase.

scholarly journals GJ 436b and the stellar wind interaction: simulations constraints using Lyα and Hα transits

2020 ◽  
Author(s):  
Carolina Villarreal D’Angelo ◽  
Aline A Vidotto ◽  
Alejandro Esquivel ◽  
Gopal Hazra ◽  
Allison Youngblood
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Planetary System ◽  
Neutral Hydrogen ◽  
Hydrogen Atmosphere ◽  
Planetary Atmosphere ◽  
Hydrodynamic Simulations ◽  
Stellar Disc ◽  
Planetary Mass ◽  
Best Fit

Abstract The GJ 436 planetary system is an extraordinary system. The Neptune-size planet that orbits the M3 dwarf revealed in the Lyα line an extended neutral hydrogen atmosphere. This material fills a comet-like tail that obscures the stellar disc for more than 10 hours after the planetary transit. Here, we carry out a series of 3D radiation hydrodynamic simulations to model the interaction of the stellar wind with the escaping planetary atmosphere. With these models, we seek to reproduce the $\sim 56\%$ absorption found in Lyα transits, simultaneously with the lack of absorption in Hα transit. Varying the stellar wind strength and the EUV stellar luminosity, we search for a set of parameters that best fit the observational data. Based on Lyα observations, we found a stellar wind velocity at the position of the planet to be around [250-460] km s−1 with a temperature of [3 − 4] × 105 K. The stellar and planetary mass loss rates are found to be 2 × 10−15 M⊙ yr−1 and ∼[6 − 10] × 109 g s−1, respectively, for a stellar EUV luminosity of [0.8 − 1.6] × 1027 erg s−1. For the parameters explored in our simulations, none of our models present any significant absorption in the Hα line in agreement with the observations.

scholarly journals IUE Observations of the Two Peculiar Binary Systems Beta Lyrae and Upsilon Sagittarii

1980 ◽  
Vol 88 ◽  
pp. 271-286 ◽  
Author(s):  
Margherita Hack ◽  
Umberto Flora ◽  
Paolo Santin
Keyword(s):  
Mass Transfer ◽  
Mass Loss ◽  
Radial Velocity ◽  
Effective Temperature ◽  
Binary Systems ◽  
Close Binaries ◽  
Infrared Excess ◽  
Show Evidence ◽  
The Common ◽  
Ultraviolet Observations

The common peculiarities of these two systems are: a) the companion is a massive object (probably m2≥10) whose spectrum is not observable; b) both systems show evidence, though in different degrees, of mass-transfer and mass-loss; c) both present, in different degrees, hydrogen deficiency; d) ultraviolet observations have shown, in both cases, the presence of lines of highly ionized elements like N V, C IV, Si IV, probably formed in an extended envelope because they do not show orbital radial velocity shifts, and cannot be explained by the effective temperature of the star whose spectrum we observe. The latter property seems to be common to several close binaries, as shown by the ultraviolet observations with IUE by Plavec and Koch (1979); e) both systems present infrared excess, suggesting the presence of an extended envelope (Gehrz et al. 1974; Lee and Nariai, 1967; Humphreys and Ney, 1974; Treffers et al. 1976).

scholarly journals On the circumstellar envelopes of semi-regular long-period variables

2018 ◽  
Vol 14 (S343) ◽  
pp. 186-190
Author(s):  
J. J. Díaz-Luis ◽  
J. Alcolea ◽  
V. Bujarrabal ◽  
M. Santander-García ◽  
M. Gómez-Garrido ◽  
...  
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Unexpected Result ◽  
Axially Symmetric ◽  
Circumstellar Envelopes ◽  
Long Period ◽  
Short Analysis Time ◽  
Line Intensity Ratio ◽  
Co Observations

AbstractThe mass loss process along the AGB phase is crucial for the formation of circumstellar envelopes (CSEs), which in the post-AGB phase will evolve into planetary nebulae (PNe). There are still important issues that need to be further explored in this field; in particular, the formation of axially symmetric PNe from spherical CSEs. To address the problem, we have conducted high S/N IRAM 30 m observations of 12COJ = 1−0 and J = 2−1, and 13COJ = 1−0 in a volume-limited unbiased sample of semi-regular variables (SRs). We also conducted Yebes 40 m SiO J = 1−0 observations in 1/2 of the sample in order to complement our 12CO observations. We report a moderate correlation between mass loss rate and the 12CO(1−0)−to−12CO(2−1) line intensity ratio, introducing a possible new method for determining mass loss rates of SRs with short analysis time. We also find that for several stars the SiO profiles are very similar to the 12CO profiles, a totally unexpected result unless these are non-standard envelopes.

scholarly journals On the Properties of Wolf-Rayet Stars and Their Mass Loss

1982 ◽  
Vol 99 ◽  
pp. 203-207
Author(s):  
N. Panagia ◽  
M. Felli
Keyword(s):  
Mass Loss ◽  
Multiple Scattering ◽  
Radiation Temperature ◽  
List Type ◽  
Type Number ◽  
Lyman Continuum ◽  
Stellar Radiation ◽  
Total Luminosity ◽  
Continuous Radiation ◽  
Photospheric Radius

From consideration of the observed properties of the envelopes produced by mass loss in WR stars we find that: a)The velocity at the optical photosphere is in the range 200–800 km sb)The effective photospheric radius for the continuous radiation capable to ionize helium twice (γ < 228 A) is typically 5 to 15 times the optical photospheric radius.c)The radiation temperature in the Lyman continuum (γ < 912 Å) is around 5 × 104K. Therefore, most of the stellar radiation is emitted in the far UV and the total luminosity is considerably higher than currently estimated.d)Multiple scattering (N ≃ 20) of radiation in the interval 228–504 Å can provide most of the momentum needed to accelerate the wind up to the observed terminal velocities.

Sign in / Sign up

Export Citation Format

Share Document