Modeling of convective motions in the envelope of procyon. II. Asymmetry of the spectral lines

Atroshchenko, I. N.; Gadun, A. S.; Kostyk, R. I.

doi:10.1007/bf01012738

Cited by 3 publications

(2 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since (except for the Sun) most of the stellar surface structure will likely remain unresolved for the nearest future, spatially averaged tools must be used, e.g. spectra integrated over the full stellar disk (Atroshchenko, Gadun, & Kostyk 1990;Dravins 1990;Dravins k Nordlund 1990a, 1990bKiselman k Nordlund 1995;Ludwig k Steffen 1995;Steffen, Ludwig, k Freytag 1995).…”

Section: Stellar Line Asymmetries and Shiftsmentioning

confidence: 99%

Stellar Surface Convection, Line Asymmetries, and Wavelength Shifts

Dravins

1999

International Astronomical Union Colloquium

View full text Add to dashboard Cite

Wavelength positions of photospheric absorption lines may be affected by surface convection (stellar granulation). Asymmetries and wavelength shifts originate from correlated velocity and brightness patterns: rising (blueshifted) elements are hot (bright), and convective blueshifts result from a larger contribution of such blueshifted photons than of redshifted ones from the sinking and cooler (darker) gas. For the Sun, the effect is around 300 m s−1, expected to increase in F-type stars, and in giants. Magnetic fields affect convection and induce lineshift variations over stellar activity cycles. A sufficient measuring precision reveals also the temporal variability of line wavelengths (due to the evolution of granules on the stellar surface). A major future development to come from adaptive optics and optical interferometry will be the study of wavelength variations across spatially resolved stars, together with their spatially resolved time variability. Thus, precise radial velocities should soon open up new vistas in stellar atmospheric physics.

show abstract

Section: Stellar Line Asymmetries and Shiftsmentioning

confidence: 99%

Stellar Surface Convection, Line Asymmetries, and Wavelength Shifts

Dravins

1999

International Astronomical Union Colloquium

View full text Add to dashboard Cite

show abstract

“…Since (except for the Sun) most of the fine structure on stellar surfaces will likely remain spatially unresolved for the nearest future, spatially averaged tools must be used, e.g. ordinary stellar spectra integrated over the full stellar disk (Atroshchenko et al 1990;Dravins 1990;Dravins k Nordlund 1990a;1990b;Kiselman k Nordlund 1995;Lites et al 1989;Ludwig k Steffen 1995;Solanki et al 1995;Steffen et al 1995).…”

mentioning

confidence: 99%

Observed and computed spectral line profiles

Dravins¹

1996

Symp. - Int. Astron. Union

View full text Add to dashboard Cite

For the diagnostics of stellar surface structure, studies of “ordinary” line profiles may prove inadequate. However, hydrodynamic models may be constrained by second-order quantities, such as line asymmetries and wavelength shifts (and especially the differential behavior between lines of different excitation potential, ionization stage, and height of formation, as well as by the time dependence).

show abstract

Properties of small-scale magnetism of stellar atmospheres

Steiner

Salhab

Freytag

et al. 2014

Publications of the Astronomical Society of Japan

View full text Add to dashboard Cite

The magnetic field outside of sunspots is concentrated in the intergranular space, where it forms a delicate filigree of bright ribbons and dots as seen on broad band images of the Sun. We expect this small-scale magnetic field to exhibit a similar behavior in stellar atmospheres. In order to find out more about it, we perform numerical simulations of the surface layers of stellar atmospheres. Here, we report on preliminary results from simulations in the range between 4000 K and 6500 K effective temperature with an initial vertical, homogeneous magnetic field of 50 G strength. We find that the field strength of the strongest magnetic flux concentrations increases with decreasing effective temperature at the height level where the average Rosseland optical depth is one. On the other hand, at the same level, the field is less strong than the thermal equipartition value in the coolest model but assumes superequipartition in the models hotter than 5000 K. While the Wilson depression of the strongest field concentrations is about one pressure scale height in the coolest model, it is more than four times the pressure scale height in the hottest one. We also find that the relative contribution of the bright filigree to the bolometric, vertically directed radiative intensity is most significant for the Teff = 5000 K model (0.6%–0.79%) and least significant for the hottest and coolest models (0.1%–0.46% and 0.14%–0.32%, respectively). This behavior suggests that the effect of the small-scale magnetic field on the photometric variability is more significant for K dwarf stars than for F-type and also M-type stars.

show abstract

Modeling of convective motions in the envelope of procyon. II. Asymmetry of the spectral lines

Cited by 3 publications

References 4 publications

Stellar Surface Convection, Line Asymmetries, and Wavelength Shifts

Stellar Surface Convection, Line Asymmetries, and Wavelength Shifts

Observed and computed spectral line profiles

Properties of small-scale magnetism of stellar atmospheres

Contact Info

Product

Resources

About