Stellar atmosphere


Stellar atmosphere

The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. It is divided into several regions of distinct character:

The photosphere, which is the lowest and coolest part of the star's atmosphere, is the part which we see. Light escaping from the surface of the star stems from this region and passes through the higher layers. The photosphere of the Sun has a temperature (effective temperature) of about 5780 K. Starspots, cool regions of disrupted magnetic field lie on the photosphere.

Above the photosphere lies the chromosphere. This part of the atmosphere first cools down and then starts to heat up to about 10 times the temperature of the photosphere.

Above the chromosphere lies the transition region, where the temperature increases rapidly on a distance of only around 100 km. Beyond this region is the outermost part of the stellar atmosphere, the corona, a tenuous but extremely hot (million K) plasma. While all stars on the main sequence feature transition regions and coronae, not all evolved stars do so. It seems that only some giants, and very few supergiants possess coronae. An unresolved problem in stellar astrophysics is the question as to how exactly the corona can be heated to such high temperatures. The answer lies in magnetic fields, but the exact mechanism remains unclear.

During a total solar eclipse, the photosphere of the Sun is obscured, revealing the other layers of the atmosphere. Under these conditions, the chromosphere appears as a rough reddish ring, and the corona appears as a tufted halo.


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Atmosphere (disambiguation) — Atmosphere (< Greek ατμός (atmos) = steam + σφαίρα (sfaíra) = sphere) or Atmospheres most commonly refers to: *Atmosphere, a layer of gases around a celestial body, such as: **Earth s atmosphere **Stellar atmosphereIt may also refer to:Science:… …   Wikipedia

  • Atmosphere of Venus — Atmosphere of Venus …   Wikipedia

  • Atmosphere — An atmosphere (from Greek ατμός atmos , vapor + σφαίρα sphaira , sphere ) is a layer of gases that may surround a material body of sufficient mass, [ [http://www.ontariosciencecentre.ca/school/clc/visits/glossary.asp Ontario Science Centre… …   Wikipedia

  • Atmosphère stellaire — Photo prise en France durant l éclipse de 1999 L’atmosphère stellaire est la région extérieure au volume d une étoile, qui repose au dessus du cœur solaire, de la zone de radiation et de la zone de convection …   Wikipédia en Français

  • Atmosphere of Earth — Air redirects here. For other uses, see Air (disambiguation). Qualities of air redirects here. It is not to be confused with Air quality …   Wikipedia

  • Atmosphere of Mars — Chemical species mole fraction Carbon dioxide 95.32% Nitrogen 2.7% Argon …   Wikipedia

  • Atmosphere of Jupiter — Cloud pattern on Jupiter in 2000 The atmosphere of Jupiter is the largest planetary atmosphere in the Solar System. It is mostly made of molecular hydrogen and helium in roughly solar proportions; other chemical compounds are present only in… …   Wikipedia

  • Atmosphere of Mercury — Atmosphere of Mercury[1] Species CD,[n 1] cm−2 SD,[n 2] cm−3 …   Wikipedia

  • Atmosphère de Pluton — Vue d artiste de Charon observé à travers l atmosphère ténue de Pluton. Informations générales Épaisseur indéterminée Pression atmosphérique …   Wikipédia en Français

  • Stellar classification — In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are… …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.