Stellar atmosphere

Last updated
Photo taken in France during the 1999 solar eclipse Solar eclipse 1999 4.jpg
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.

Contents

Overview

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

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

Notes

  1. 1 2 ""Beyond the Blue Horizon" – A Total Solar Eclipse Chase". 1999-08-05. Retrieved 2010-05-21. 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.
  3. 1 2 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 . S2CID   119426022.
  6. R.C. Altrock (2004). "The Temperature of the Low Corona During Solar Cycles 21–23". Solar Physics. 224 (1–2): 255. Bibcode:2004SoPh..224..255A. doi:10.1007/s11207-005-6502-4. S2CID   121468084.
  7. "The Sun's Corona – Introduction". NASA . Retrieved 2010-05-21. 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; Lallement, Rosine; Slavin, Jonathan D. (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 . hdl: 20.500.11850/585419 . ISSN   0038-6308.
  9. "Sun: Facts". NASA Science. 2017-11-14. Retrieved 2023-10-11.
  10. "Components of the Heliosphere". NASA. 2013-01-25. Retrieved 2023-10-11.
  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. Vol. 2 (1 ed.). Cambridge University Press. p. 460. doi:10.1017/S1743921307006163. ISBN   978-0-521-86348-3. S2CID   123028350.{{cite book}}: |journal= ignored (help)

Related Research Articles

<span class="mw-page-title-main">Stellar corona</span> Outermost layer of a stars atmosphere

A corona is the outermost layer of a star's atmosphere. It consists of plasma.

<span class="mw-page-title-main">Sun</span> Star in the Solar System

The Sun is the star at the center of the Solar System. It is a massive, hot ball of plasma, inflated and heated by energy produced by nuclear fusion reactions at its core. Part of this internal energy is emitted from its surface as light, ultraviolet, and infrared radiation, providing most of the energy for life on Earth.

<span class="mw-page-title-main">Solar wind</span> Stream of charged particles from the Sun

The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. The composition of the solar wind plasma also includes a mixture of materials found in the solar plasma: trace amounts of heavy ions and atomic nuclei of elements such as C, N, O, Ne, Mg, Si, S, and Fe. There are also rarer traces of some other nuclei and isotopes such as P, Ti, Cr, and 58Ni, 60Ni, and 62Ni. Superimposed with the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field. The boundary separating the corona from the solar wind is called the Alfvén surface.

<span class="mw-page-title-main">X-ray astronomy</span> Branch of astronomy that uses X-ray observation

X-ray astronomy is an observational branch of astronomy which deals with the study of X-ray observation and detection from astronomical objects. X-radiation is absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to high altitude by balloons, sounding rockets, and satellites. X-ray astronomy uses a type of space telescope that can see x-ray radiation which standard optical telescopes, such as the Mauna Kea Observatories, cannot.

<span class="mw-page-title-main">Chromosphere</span> Layer in the Suns atmosphere above the photosphere

A chromosphere is the second layer of a star's atmosphere, located above the photosphere and below the solar transition region and corona. The term usually refers to the Sun's chromosphere, but not exclusively.

<span class="mw-page-title-main">Heliosphere</span> Region of space dominated by the Sun

The heliosphere is the magnetosphere, astrosphere, and outermost atmospheric layer of the Sun. It takes the shape of a vast, tailed bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interstellar medium. The "bubble" of the heliosphere is continuously "inflated" by plasma originating from the Sun, known as the solar wind. Outside the heliosphere, this solar plasma gives way to the interstellar plasma permeating the Milky Way. As part of the interplanetary magnetic field, the heliosphere shields the Solar System from significant amounts of cosmic ionizing radiation; uncharged gamma rays are, however, not affected. Its name was likely coined by Alexander J. Dessler, who is credited with the first use of the word in the scientific literature in 1967. The scientific study of the heliosphere is heliophysics, which includes space weather and space climate.

<span class="mw-page-title-main">Local Interstellar Cloud</span> Interstellar cloud in the Milky Way Galaxy

The Local Interstellar Cloud (LIC), also known as the Local Fluff, is an interstellar cloud roughly 30 light-years (9.2 pc) across, through which the Solar System is moving. This feature overlaps with a region around the Sun referred to as the solar neighborhood. It is unknown whether the Sun is embedded in the Local Interstellar Cloud, or is in the region where the Local Interstellar Cloud is interacting with the neighboring G-Cloud. Like the G-Cloud and others, the LIC is part of the Very Local Interstellar Medium which begins where the heliosphere and interplanetary medium end, the furthest that probes have traveled.

<span class="mw-page-title-main">Solar prominence</span> Structure extending off of the Suns surface

A prominence, sometimes referred to as a filament, is a large plasma and magnetic field structure extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the solar corona. While the corona consists of extremely hot plasma, prominences contain much cooler plasma, similar in composition to that of the chromosphere.

Solar physics is the branch of astrophysics that specializes in the study of the Sun. It deals with detailed measurements that are possible only for our closest star. It intersects with many disciplines of pure physics, astrophysics, and computer science, including fluid dynamics, plasma physics including magnetohydrodynamics, seismology, particle physics, atomic physics, nuclear physics, stellar evolution, space physics, spectroscopy, radiative transfer, applied optics, signal processing, computer vision, computational physics, stellar physics and solar astronomy.

<span class="mw-page-title-main">Outline of astronomy</span>

The following outline is provided as an overview of and topical guide to astronomy:

<span class="mw-page-title-main">Solar transition region</span> Layer of the Suns atmosphere above the chromosphere and below the corona

The solar transition region is a region of the Sun's atmosphere between the upper chromosphere and corona. It is important because it is the site of several unrelated but important transitions in the physics of the solar atmosphere:

<span class="mw-page-title-main">Coronal loop</span> Arch-like structure in the Suns corona

In solar physics, a coronal loop is a well-defined arch-like structure in the Sun's atmosphere made up of relatively dense plasma confined and isolated from the surrounding medium by magnetic flux tubes. Coronal loops begin and end at two footpoints on the photosphere and project into the transition region and lower corona. They typically form and dissipate over periods of seconds to days and may span anywhere from 1 to 1,000 megametres in length.

<span class="mw-page-title-main">Red giant</span> Type of large cool star that has exhausted its core hydrogen

A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around 5,000 K or lower. The appearance of the red giant is from yellow-white to reddish-orange, including the spectral types K and M, sometimes G, but also class S stars and most carbon stars.

<span class="mw-page-title-main">Astrophysical X-ray source</span> Astronomical object emitting X-rays

Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays.

<span class="mw-page-title-main">Interface Region Imaging Spectrograph</span> NASA satellite of the Explorer program

Interface Region Imaging Spectrograph (IRIS), also called Explorer 94 and SMEX-12, is a NASA solar observation satellite. The mission was funded through the Small Explorer program to investigate the physical conditions of the solar limb, particularly the interface region made up of the chromosphere and transition region. The spacecraft consists of a satellite bus and spectrometer built by the Lockheed Martin Solar and Astrophysics Laboratory (LMSAL), and a telescope provided by the Smithsonian Astrophysical Observatory (SAO). IRIS is operated by LMSAL and NASA's Ames Research Center.

<span class="mw-page-title-main">Nanoflare</span> Type of episodic heating event

A nanoflare is a very small episodic heating event which happens in the corona, the external atmosphere of the Sun.

<span class="mw-page-title-main">Coronal radiative losses</span>

In astronomy and in astrophysics, for radiative losses of the solar corona, it is meant the energy flux radiated from the external atmosphere of the Sun, and, in particular, the processes of production of the radiation coming from the solar corona and transition region, where the plasma is optically-thin. On the contrary, in the chromosphere, where the temperature decreases from the photospheric value of 6000 K to the minimum of 4400 K, the optical depth is about 1, and the radiation is thermal.

<span class="mw-page-title-main">Heliophysics Science Division</span>

The Heliophysics Science Division of the Goddard Space Flight Center (NASA) conducts research on the Sun, its extended Solar System environment, and interactions of Earth, other planets, small bodies, and interstellar gas with the heliosphere. Division research also encompasses geospace—Earth's uppermost atmosphere, the ionosphere, and the magnetosphere—and the changing environmental conditions throughout the coupled heliosphere.

<span class="mw-page-title-main">AZ Cancri</span> Star in the constellation Cancer

AZ Cancri (AZ Cnc) is a M-type flare star in the constellation Cancer. It has an apparent visual magnitude of approximately 17.59.

<span class="mw-page-title-main">Alfvén surface</span> Boundary between solar corona and wind

The Alfvén surface is the boundary separating a star's corona from the stellar wind defined as where the coronal plasma's Alfvén speed and the large-scale stellar wind speed are equal. It is named after Hannes Alfvén, and is also called Alfvén critical surface, Alfvén point, or Alfvén radius. Parker Solar Probe became the first spacecraft that crossed Alfvén surface of the Sun.