The color-magnitude diagram for galaxies shows the dependence of the absolute magnitude on the mass of the galaxy. The primary description of the individual regions on the diagram was given in 2003 by Eric Bell ( Eng. Eric F. Bell ) and colleagues using the results of the COMBO-17 survey [1], which helped clarify the bimodal distribution of red and blue galaxies observed in the analysis of SDSS data [2] and even noted by de Vaucouleur when analyzing the morphology of galaxies in 1961. [3] There are three distinct areas in the diagram: the red sequence , the green valley, and the blue cloud . The red sequence includes most red galaxies, mostly elliptical . The blue cloud contains most of the blue galaxies, which are usually spiral . Between these areas is a sparsely populated area known as the green valley, including some red spiral galaxies. In contrast to the comparable situation, the Hertzsprung-Russell diagrams for stars, the properties of galaxies are not completely determined by the position on the color-magnitude diagram. The diagram also has evolution over time: the red sequence at earlier stages of the history of the Universe was more constant in color in the considered range of stellar magnitudes, and the blue cloud was less uniformly filled.
New studies show that the green valley consists of two different populations of galaxies: late-type galaxies, where star formation ceased due to exhaustion of gas reserves for billions of years, and early-type galaxies, in which gas reserves were quickly destroyed by merging with other galaxies or in the presence of active core. [five]
The Milky Way and the Andromeda Galaxy are considered to be in the green valley, as star formation in them slows down due to the gradual exhaustion of gas. [6]
Notes
- ↑ Bell, Eric F. et al. Nearly 5000 Distant Early ‐ Type Galaxies in COMBO ‐ 17: A Red Sequence and Its Evolution since z = 1 , The Astrophysical Journal , 608: 752–767, 2004 June 20. [1]
- ↑ Strateva, I., et al. Color Separation of Galaxy Types in the Sloan Digital Sky Survey Imaging Data , 2001, The Astronomical Journal , 122, 1861 [2]
- ↑ de Vaucouleurs, G. Integrated Colors of Bright Galaxies in the u, b, V System. 1961, The Astrophysical Journal Supplement Series , 5, 233. [3]
- ↑ A Deep Look into a Dark Sky , ESO Picture of the Week . Date of treatment August 8, 2014.
- ↑ Schawinski, Kevin; Urry, C. Megan; Simmons, Brooke D .; Fortson, Lucy; Kaviraj, Sugata; Keel, William C .; Lintott, Chris J .; Masters, Karen L .; Nichol, Robert C .; Sarzi, Marc; Ramin; Skibba Treister, Ezequiel; Willett, Kyle W .; Wong, O. Ivy; Yi, Sukyoung K. The Green Valley is a Red Herring: Galaxy Zoo reveals two evolutionary pathways towards quenching of star formation in early- and late-type galaxies ( journal ) : journal. - 2014 .-- DOI : 10.1093 / mnras / stu327 . - . - arXiv : 1402.4814 .
- ↑ Mutch, SJ; Croton, DJ; Poole, GB The Mid-life Crisis of the Milky Way and M31 // The Astrophysical Journal : journal. - IOP Publishing 2011. - Vol. 736 , no. 2 . - DOI : 10.1088 / 0004-637X / 736/2/84 . - . - arXiv : 1105.2564 .