Flicker (astronomy)

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In stellar physics, the term flicker describes stochastic changes in brightness of sun-like stars with periods of less than 8 hours.

root cause

Sun-like stars transport energy in their photosphere mainly by means of convection . As a result, gas bubbles rise and are reflected at the jump in density at the transition to the chromosphere . As a result, density waves ( acoustic oscillations , similar to the 5-minute period of the sun ) run into the star, the superposition of which leads to a characteristic frequency spectrum .

In addition, there are changes in brightness in sun-like stars due to the appearance and descent of granules in the photosphere.

application

Depending on the type of spectral , the depth of the convection zone increases, with which the speed of the ascending convection cells also changes. From this, indirectly, with the help of the frequency spectrum, the surface acceleration of the star can be derived, with an accuracy of approx. 25 percent, which is better than with another photometric method, the spectroscopic observation.

From the surface acceleration, which was determined via the flicker, - similar to asteroseismology - the fundamental star parameters mass and radius can be inferred.

Definition of terms

The similar term Flickering in describing Astrophysics short-term brightness variations on the order of seconds in the accretion of matter onto a compact arise star.

literature

  • Fabienne A. Bastien, Keivan G. Stassun, Joshua Pepper: Larger Planet Radii Inferred from Stellar "Flicker" Brightness Variations of Bright Planet Host Stars . In: Astrophysics. Solar and Stellar Astrophysics . 2014, arxiv : 1405.0940v1 .
  • David M. Kipping, Fabienne A. Bastien, Keivan G. Stassun, William J. Chaplin, Daniel Huber, Lars A. Buchhave: FLICKER AS A TOOL FOR CHARACTERIZING PLANETS THROUGH ASTERODENSITY PROFILING . In: Astrophysics. Solar and Stellar Astrophysics . 2014, arxiv : 1403.5264v1 .
  • Steven R. Cranmer, Fabienne A. Bastien, Keivan G. Stassun, Steven H. Saar: STELLAR GRANULATION AS THE SOURCE OF HIGH-FREQUENCY FLICKER IN KEPLER LIGHT CURVES . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1312.5928v1 .
  • Fabienne A. Bastien, Keivan G. Stassun, Gibor Basri, Joshua Pepper: An observational correlation between stellar brightness variations and surface gravity . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1308.4728v1 .