Stellar atmosphere

Short description: Outer region of the volume of a star

Photo taken in France during the 1999 solar eclipse

The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone.

## Overview

The stellar atmosphere is divided into several regions of distinct character:

* The photosphere, which is the atmosphere's lowest and coolest layer, is normally its only visible part.[1] Light escaping from the surface of the star stems from this region and passes through the higher layers. The Sun's photosphere has a temperature in the 5,770–5,780 K (5,500–5,510 °C; 9,930–9,940 °F) range.[2][3] Starspots, cool regions of disrupted magnetic field, lie in the photosphere.[3]
* 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 (62 mi).[4]
* Additionally, many stars have a molecular layer (MOLsphere) above the photosphere and just beyond or even within the chromosphere.[5] The molecular layer is cool enough to contain molecules rather than plasma, and may consist of such components as carbon monoxide, water vapor, silicon monoxide, and titanium oxide.
* The outermost part of the stellar atmosphere, or upper stellar atmosphere, is the corona, a tenuous plasma which has a temperature above one million Kelvin.[6] 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 how the corona can be heated to such high temperatures. The answer is believed to lie in magnetic fields, but the exact mechanism remains unclear.[7]
* The astrosphere, which is in the case of the Sun the heliosphere,[8] can be in a broader understanding considered the furthest part of a stellar atmosphere,[9][10] before interstellar space begins at the heliopause. The astrosphere is not to be confused with the Solar System and its outermost region the Oort cloud, which extends much further than the astrosphere, therefore far into interstellar space.

During a total solar eclipse, the photosphere of the Sun is obscured, revealing its atmosphere's other layers.[1] Observed during eclipse, the Sun's chromosphere appears (briefly) as a thin pinkish arc,[11] and its corona is seen as a tufted halo. The same phenomenon in eclipsing binaries can make the chromosphere of giant stars visible.[12]

## See also

* Cecilia Payne-Gaposchkin, who first proposed the presently-accepted composition of stellar atmospheres
* Circumstellar envelope
* Heliosphere

## Notes

1. ↑ 1.0 1.1 ""Beyond the Blue Horizon" – A Total Solar Eclipse Chase". 1999-08-05. https://www.sciencedaily.com/releases/1999/08/990805111308.htm. "On ordinary days, the corona is hidden by the blue sky, since it is about a million times fainter than the layer of the sun we see shining every day, the photosphere."
2. ↑ Mariska, J. T. (1992). The solar transition region. Cambridge Astrophysics Series. Cambridge University Press. ISBN 978-0-521-38261-8. https://cambridge.org/catalogue/catalogue.asp?isbn=9780521382618&ss=toc.
3. ↑ 3.0 3.1 Lang, K. R. (September 2006). "5.1 MAGNETIC FIELDS IN THE VISIBLE PHOTOSPHERE". Sun, earth, and sky (2nd ed.). Springer. p. 81. ISBN 978-0-387-30456-4. "this opaque layer is the photosphere, the level of the Sun from which we get our light and heat"
4. ↑ Mariska, J. T. (1992). The solar transition region. Cambridge University Press. p. 60. ISBN 978-0-521-38261-8. "100 km suggested by average models"
5. ↑ Tsuji, Takashi (2006). "Infrared Spectra and Visibilities as Probes of the Outer Atmospheres of Red Supergiant Stars". The Astrophysical Journal 645 (2): 1448–1463. doi:10.1086/504585.
6. ↑ R.C. Altrock (2004). "The Temperature of the Low Corona During Solar Cycles 21–23". Solar Physics 224 (1–2): 255. doi:10.1007/s11207-005-6502-4. Bibcode: 2004SoPh..224..255A. https://zenodo.org/record/1232838.
7. ↑ "The Sun's Corona – Introduction". NASA. http://imagine.gsfc.nasa.gov/docs/science/mysteries_l1/corona.html. "Now most scientists believe that the heating of the corona is linked to the interaction of the magnetic field lines."
8. ↑ Sterken, Veerle J.; Baalmann, Lennart R.; Draine, Bruce T.; Godenko, Egor; Herbst, Konstantin; Hsu, Hsiang-Wen; Hunziker, Silvan; Izmodenov, Vladislav et al. (2022). "Dust in and Around the Heliosphere and Astrospheres". Space Science Reviews (Springer Science and Business Media LLC) 218 (8). doi:10.1007/s11214-022-00939-7. ISSN 0038-6308.
9. ↑ "Sun: Facts". 2017-11-14. https://science.nasa.gov/sun/facts/.
10. ↑ "Components of the Heliosphere". 2013-01-25. https://www.nasa.gov/image-article/components-of-heliosphere/#:~:text=influence in space.-,The Heliosphere is the outer atmosphere of the Sun and,planets in our solar system..
11. ↑ Lewis, J.S. (2004-02-23). Physics and chemistry of the solar system (Second ed.). Elsevier Academic Press. p. 87. ISBN 978-0-12-446744-6. "The dominant color is influenced by the Balmer radiation of atomic hydrogen"
12. ↑ Griffin, R.E. (2007-08-27). Hartkopft, W.I.; Guinan, E.F.. eds. Only Binary Stars Can Help Us Actually SEE a Stellar Chromosphere. 2 (1 ed.). Cambridge University Press. 460. doi:10.1017/S1743921307006163. ISBN 978-0-521-86348-3.

* v
* t
* e

The Sun

Internal structure|

* Core
* Radiation zone
* Tachocline
* Convection zone

Atmosphere|

| Photosphere|

* Supergranulation
* Granule
* Faculae
* Sunspot

|

Chromosphere|

* Plage
* Spicule
* Moreton wave

Corona|

* Transition region
* Coronal hole
* Coronal loop
* Coronal mass ejection
* Prominence
* Helmet streamer
* Supra-arcade downflows

Variation|

* Solar cycle
* List of solar cycles
* Solar maximum
* Solar minimum
* Wolf number
* Solar wind
* Flare
* Helioseismology

Heliosphere|

* Current sheet
* Termination shock
* Heliosheath
* Heliopause
* Bow shock

Related|

* Heliophysics
* Solar activity
* Solar astronomy
* Solar dynamo
* Eclipse
* Solar energy
* Solar neutrino
* Solar observation
* Solar phenomena
* Solar physics
* Solar System
* Solar telescope
* Solar time
* Space climate
* Space weather
* Standard solar model
* Star
* Sunlight radiation

* Spectral class: G-type main-sequence star

* v
* t
* e

Atmospheres

Star|

* Sun

Exoplanet|

* HD 209458 b
* Kepler-7b

Planet|

* Mercury
* Venus
* Earth
* Mars
* Jupiter
* Saturn
* Uranus
* Neptune

Dwarf planet|

* Ceres
* Pluto
* Makemake

Satellite|

* Callisto
* Dione
* Enceladus
* Europa
* Ganymede
* Io
* Moon
* Rhea
* Titan
* Triton

See also|

* Coma (cometary)
* Extraterrestrial atmosphere
* Stellar atmosphere

* v
* t
* e

Stars

Formation|

* Accretion
* Molecular cloud
* Bok globule
* Young stellar object
* Protostar
* Pre-main-sequence
* Herbig Ae/Be
* T Tauri
* FU Orionis
* Herbig–Haro object
* Hayashi track
* Henyey track

Evolution|

* Main sequence
* Red-giant branch
* Horizontal branch
* Red clump
* Asymptotic giant branch
* Blue loop
* Protoplanetary nebula
* Planetary nebula
* PG1159
* Dredge-up
* Instability strip
* Luminous blue variable
* Blue straggler
* Stellar population
* Supernova
* Superluminous supernova / Hypernova

Spectral
classification|

* Early
* Late
* Main sequence
* O
* B
* A
* F
* G
* K
* M
* Brown dwarf
* WR
* OB
* Subdwarf
* O
* B
* Subgiant
* Giant
* Blue
* Red
* Yellow
* Bright giant
* Supergiant
* Blue
* Red
* Yellow
* Hypergiant
* Yellow
* Carbon
* S
* CN
* CH
* White dwarf
* Chemically peculiar
* Am
* Ap/Bp
* HgMn
* Helium-weak
* Barium
* Extreme helium
* Lambda Boötis
* Lead
* Technetium
* Be
* Shell
* B[e]

Remnants|

* White dwarf
* Helium planet
* Black dwarf
* Neutron
* Radio-quiet
* Pulsar
* Binary
* X-ray
* Magnetar
* Stellar black hole
* X-ray binary
* Burster

Hypothetical|

* Blue dwarf
* Green
* Black dwarf
* Exotic
* Boson
* Electroweak
* Strange
* Preon
* Planck
* Dark
* Dark-energy
* Quark
* Q
* Black
* Gravastar
* Frozen
* Quasi-star
* Thorne–Żytkow object
* Iron
* Blitzar

Stellar
nucleosynthesis|

* Deuterium burning
* Lithium burning
* Proton–proton chain
* CNO cycle
* Helium flash
* Triple-alpha process
* Alpha process
* Carbon burning
* Neon burning
* Oxygen burning
* Silicon burning
* S-process
* R-process
* Fusor
* Nova
* Symbiotic
* Remnant
* Luminous red nova

Structure|

* Core
* Convection zone
* Microturbulence
* Oscillations
* Radiation zone
* Atmosphere
* Photosphere
* Starspot
* Chromosphere
* Corona
* Stellar wind
* Bubble
* Bipolar outflow
* Accretion disk
* Asteroseismology
* Helioseismology
* Eddington luminosity
* Kelvin–Helmholtz mechanism

Properties|

* Designation
* Dynamics
* Effective temperature
* Luminosity
* Kinematics
* Magnetic field
* Absolute magnitude
* Mass
* Metallicity
* Rotation
* Starlight
* Variable
* Photometric system
* Color index
* Hertzsprung–Russell diagram
* Color–color diagram

Star systems|

* Binary
* Contact
* Common envelope
* Eclipsing
* Symbiotic
* Multiple
* Cluster
* Open
* Globular
* Super
* Planetary system

Earth-centric
observations|

* Sun
* Solar System
* Sunlight
* Pole star
* Circumpolar
* Constellation
* Asterism
* Magnitude
* Apparent
* Extinction
* Photographic
* Radial velocity
* Proper motion
* Parallax
* Photometric-standard

Lists|

* Proper names
* Arabic
* Chinese
* Extremes
* Most massive
* Highest temperature
* Largest volume
* Smallest volume
* Brightest
* Historical
* Most luminous
* Nearest
* Nearest bright
* With exoplanets
* Brown dwarfs
* White dwarfs
* Milky Way novae
* Supernovae
* Candidates
* Remnants
* Planetary nebulae
* Timeline of stellar astronomy

Related articles|

* Substellar object
* Brown dwarf
* Sub-brown dwarf
* Planet
* Galactic year
* Galaxy
* Guest
* Gravity
* Intergalactic
* Starfield
* Tidal disruption event

'Category:Stars * '

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/Stellar atmosphere. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Astronomy:Stellar_atmosphere&oldid=411398"
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template