Generation of mass loss in K giants: The failure of global oscillation modes and possible implications

1995 ◽  
Vol 442 ◽  
pp. L61 ◽  
Author(s):  
G. Sutmann ◽  
M. Cuntz
Keyword(s):  
Mass Loss ◽  
Global Oscillation ◽  
Oscillation Modes ◽  
K Giants

scholarly journals Li Enrichment, Mass Loss, and CN Abundances in High Rotating K Giants

2004 ◽  
Vol 215 ◽  
pp. 242-243
Author(s):  
N. A. Drake ◽  
R. de la Reza ◽  
L. da Silva ◽  
D. L. Lambert
Keyword(s):  
Mass Loss ◽  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Mixing Process ◽  
Stellar Activity ◽  
New Models ◽  
Low Mass ◽  
K Giants

High rotating low-mass K giants can be considered as interesting new “laboratories” for studies of the mixing process and mass loss. By means of high spectral resolution observations of some rapidly rotating K giants we found a series of connections between rotation, stellar activity, high Li abundance and mass loss. These giants show low 14N and high 13C enrichment. Nearly half of them are Li rich. This frequency is much higher than the ~ 2% corresponding to common, low rotating K giants. They are also the most suitable objects to test new models of rotation-induced mixing or planet engulfing scenarios.

scholarly journals Global Oscillations of Masing Disks in Megamasers

1999 ◽  
Vol 194 ◽  
pp. 90-91
Author(s):  
Atsuo T. Okazaki
Keyword(s):  
Velocity Distribution ◽  
Rotation Velocity ◽  
Angular Rotation ◽  
Global Oscillation ◽  
Oscillation Modes ◽  
Ngc 1068

We study the characteristics of global oscillation modes of masing disks in megamasers and the effect of the modes on the disk kinematics. We find that the eccentric mode is responsible for the observed sub-Keplerian velocity distribution of the maser source of NGC 1068, whereas in the masing disk of NGC 4258 the warping mode is dominant so that the angular rotation velocity remains near Keplerian.

scholarly journals Effects of Superfluidity on Spheroidal Oscillations of Neutron Stars

1994 ◽  
Vol 147 ◽  
pp. 586-590
Author(s):  
Umin Lee ◽  
T.J.B. Collins ◽  
H.M. Van Horn ◽  
R.I. Epstein
Keyword(s):  
Wave Propagation ◽  
Neutron Star ◽  
Neutron Stars ◽  
Short Wavelength ◽  
Surface Gravity ◽  
Frequency Spectra ◽  
Global Oscillation ◽  
Oscillation Modes ◽  
Outer Crust ◽  
Spheroidal Oscillations

AbstractIn the limit of short wavelengths, it has been shown that superfluidity significantly affects wave propagation in neutron stars. Here we abandon the short-wavelength restriction and extend these calculations to global oscillation modes. In the present analysis, the solid crust of the neutron star is divided into an outer crust and an inner crust, and a superfluid of neutrons coexists with the solid lattice in the inner crust. We have computed several low-order global spheroidal modes for l = 2 both with and without superfluidity. We find that superfluidity in the inner crust affects the frequency spectra of acoustic (p-) modes, shear (s-) modes, and interfacial (i-) modes, although the surface gravity (g-) modes are not affected at all.

Solar atmospheric magnetic effects on global acoustic and atmospheric gravity eigenoscillations

2005 ◽  
Vol 364 (1839) ◽  
pp. 541-545
Author(s):  
Balázs Pintér
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Line Width ◽  
Solar Oscillations ◽  
Layer Model ◽  
Global Oscillation ◽  
Plane Parallel ◽  
Oscillation Modes ◽  
Atmospheric Gravity

Solar global observations suggest that the frequency and the line width of helioseismic acoustic eigenmodes vary with the solar cycle. One reason for the measured changes could be the variation of the global atmospheric magnetic fields. We model global solar oscillations in a plane-parallel, three-layer model within the framework of linear dissipative magnetohydrodynamics, and study the effects of a homogenous, horizontal atmospheric magnetic field on global oscillations. We find magnetoacoustic f - and p -modes and also atmospheric gravity modes ( g -modes) among the eigenoscillations of the system. We conclude that changes in the atmospheric magnetic field can, significantly, shift the frequencies and vary the line width of global oscillation modes.

scholarly journals Far-infrared study of K giants in the solar neighborhood: Connection between Li enrichment and mass-loss

2015 ◽  
Vol 577 ◽  
pp. A10 ◽  
Author(s):  
Yerra Bharat Kumar ◽  
B. E. Reddy ◽  
C. Muthumariappan ◽  
G. Zhao
Keyword(s):  
Mass Loss ◽  
Far Infrared ◽  
Solar Neighborhood ◽  
Infrared Study ◽  
K Giants

scholarly journals Theory of Global Disk Oscillations

2000 ◽  
Vol 175 ◽  
pp. 409-421 ◽  
Author(s):  
Atsuo T. Okazaki
Keyword(s):  
Angular Momentum ◽  
Radial Flow ◽  
Global Oscillation ◽  
Oscillation Model ◽  
Oscillation Modes

AbstractWe discuss the characteristics of global oscillation modes in Be disks and review recent studies related to the disk oscillation model. Since the m = 1 modes are present only in near Keplerian disks and the mode confinement occurs only in the region in which the radial flow is subsonic, the model of global disk oscillation strongly prefers the viscous decretion disk scenario proposed by Lee et al. (1991), whereas it is incompatible with the wind-compressed disk scenario of Bjorkman & Cassinelli (1993), which predicts angular-momentum conserving disks with supersonic radial flow. Based on the viscous decretion disk scenario, we discuss transonic solutions of decretion and examine the effect of viscosity on the global one-armed modes.

scholarly journals The s-Process in the Yellow Symbiotic AG Draconis

2000 ◽  
Vol 177 ◽  
pp. 103-104
Author(s):  
Katia Cunha ◽  
Verne V. Smith ◽  
Alain Jorissen
Keyword(s):  
Mass Loss ◽  
Binary Systems ◽  
Mass Loss Rate ◽  
Asymptotic Giant Branch ◽  
Element Abundance ◽  
Neutron Density ◽  
Symbiotic Stars ◽  
Solar Metallicity ◽  
Low Metallicity ◽  
K Giants

An abundance analysis of the yellow symbiotic system AG Draconis reveals it to be a metal-poor K giant ([Fe/H] = −1.3) which is enriched in the heavy s-process elements. This star thus provides a link between the symbiotic stars and the binary barium and CH stars which are also s-process enriched. These binary systems, which exhibit overabundances of the heavy elements, owe their abundance peculiarities to mass transfer from thermally-pulsing asymptotic giant branch stars, which have since evolved to become white-dwarf companions of the cool stars we now view as the chemically peculiar primaries. A comparison of the heavy-element abundance distribution in AG Dra with theoretical nucleosynthesis calculations shows that the s-process is defined by a relatively large neutron exposure (τ = 1.3 mb−1), while an analysis of the rubidium abundance suggests that the s-process occurred at a neutron density of about 2 × 108 cm−3. The derived spectroscopic orbit of AG Dra is similar to the orbits of barium and CH stars. Because the luminosity function of low-metallicity K giants is skewed towards higher luminosities by about 2 magnitudes relative to solar-metallicity giants, it is argued that the lower metallicity K giants have larger mass-loss rates. It is this larger mass-loss rate that drives the symbiotic phenomena in AG Dra and we suggest that the other yellow symbiotic stars are probably low-metallicity objects as well.

Sign in / Sign up

Export Citation Format

Share Document