Tip of the Red Giant Branch
The Tip of the Red Giant Branch (English translation: tip of the Red giant branch ) is a method of astronomy for determining the distance of star clusters and galaxies. It is based on that all red giants during the ignition of helium burning in the infrared have an identical brightness.
In the development of intermediate-mass stars, the ashes of hydrogen burning accumulated in a helium nucleus in the center of the star. While the hydrogen burning in a shell moves outward, the star moves in the Hertzsprung -Russell diagram along the Red giant branch upwards. In the degenerate core helium fused explosive, the luminosity depends on the mass of the nucleus and only weakly dependent on metallicity. Since the ignition of the helium nucleus mainly depends on the density, the helium flash occurs in all stars with ages 4 to 12 billion years in the same core mass.
The luminosity of the red giant at this point differs only by 0.05 mag in the mid-infrared spectral range and this is only slightly influenced by the absorbance. The method is available for all star systems with stars of the old population II, which are present in all types of globular clusters and galaxies. In order to determine the tip of the giant branch with a high accuracy, about 100 stars are within 1 like at the upper end of the red giant branch is required.
Cite
- Gyoon Myung Lee, In Sung Jang: The Tip of the Red Giant Branch Distances to Type Ia Supernova Host Galaxies. M66 and M96 II in the Leo I Group. In: Astrophysics. Solar and Stellar Astrophysics. 2013, arXiv: 1306.2306v1.
- G. A. Tammann, B. Reindl: The supernova Ia 2011fe in M101, its tip of the red -giant branch ( TRGB ) distance, and the value of H_0. In: Astrophysics. Solar and Stellar Astrophysics. 2011, arXiv: 1112.0439v1.
- M. Bellazzini: The Tip of the Red Giant Branch. In: Astrophysics. Solar and Stellar Astrophysics. 2007, arXiv: 0711.2016v1.
- Observation method of Astronomy