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Lyman continuum photons

April 09, 2024

"LyC" redirects here. For other uses, see LYC (disambiguation).

Lyman continuum photons (abbrev. LyC), shortened to Ly continuum photons or Lyc photons, are the photons emitted from stars or active galactic nuclei at photon energies above the Lyman limit. Hydrogen is ionized by absorbing LyC. Working from Victor Schumann's discovery of ultraviolet light, from 1906 to 1914, Theodore Lyman observed that atomic hydrogen absorbs light only at specific frequencies (or wavelengths) and the Lyman series is thus named after him.[1][2] All the wavelengths in the Lyman series are in the ultraviolet band. This quantized absorption behavior occurs only up to an energy limit, known as the ionization energy. In the case of neutral atomic hydrogen, the minimum ionization energy is equal to the Lyman limit, where the photon has enough energy to completely ionize the atom, resulting in a free proton and a free electron. Above this energy (below this wavelength), all wavelengths of light may be absorbed. This forms a continuum in the energy spectrum; the spectrum is continuous rather than composed of many discrete lines, which are seen at lower energies.[3][4]

The Lyman Series

The Lyman limit is at the wavelength of 91.2 nm (912 Å), corresponding to a frequency of 3.29 million GHz and a photon energy of 13.6 eV.[3] LyC energies are mostly in the ultraviolet C portion of the electromagnetic spectrum (see Lyman series). Although X-rays and gamma-rays will also ionize a hydrogen atom, there are far fewer of them emitted from a star's photosphere—LyC are predominantly UV-C. The photon absorption process leading to the ionization of atomic hydrogen can occur in reverse: an electron and a proton can collide and form atomic hydrogen. If the two particles were traveling slowly (so that kinetic energy can be ignored), then the photon the atom emits upon its creation will theoretically be 13.6 eV (in reality, the energy will be less if the atom is formed in an excited state). At faster speeds, the excess (kinetic) energy is radiated (but momentum must be conserved) as photons of lower wavelength (higher energy). Therefore, photons with energies above 13.6 eV are emitted by the combination of energetic protons and electrons forming atomic hydrogen, and emission from photoionized hydrogen.

See also edit

References edit

  1. ^ Lyman, Theodore (1906), "The Spectrum of Hydrogen in the Region of Extremely Short Wave-Length", Memoirs of the American Academy of Arts and Sciences, New Series, 13 (3): 125–146, Bibcode:1906MAAAS..13..125L, doi:10.2307/25058084, ISSN 0096-6134, JSTOR 25058084, In a preliminary paper1 the author has given the wave-length of more than one hundred and thirty lines in the region of the spectrum lying between the values 1850 and 1030 tenth metres. It is the object of the present paper to compare the results obtained by the author with those given by Schumann; to describe the apparatus used in this research and to call attention to some new facts which have come to light since the publication of the first notice.
  2. ^ Lyman, Theodore (1914), "An Extension of the Spectrum in the Extreme Ultra-Violet", Nature, 93 (2323): 241, Bibcode:1914Natur..93..241L, doi:10.1038/093241a0
  3. ^ a b Dipankar Bhattacharya (August–December 2003). "Matter and Radiation" (PDF). Fundamentals of Astrophysics. India: Inter-University Centre for Astronomy and Astrophysics. In most situations, the total emission by the free-free process far exceeds the recombination radiation, but the recombination radiation can introduce characteristic spectral features at ionisation thresholds in the continuum radiation. For Hydrogen, the highest ionisation threshold, called the Lyman Limit, corresponds to an energy of 13.6 eV or an wavelength of 912Å. Recombination radiation from Hydrogen at wavelengths shorter than this is called the "Lyman continuum".
  4. ^ . A Dictionary of Astronomy. 1997. Archived from the original on May 23, 2011. Lyman limit The short-wavelength end of the hydrogen Lyman series, at 91.2 nm. It corresponds to the energy required for an electron in the hydrogen ground state to jump completely out of the atom, leaving the atom ionized.
  5. ^ Flury, Sophia R.; Jaskot, Anne E.; Ferguson, Harry C.; Worseck, Gábor; Makan, Kirill; Chisholm, John; Saldana-Lopez, Alberto; Schaerer, Daniel; McCandliss, Stephan; Wang, Bingjie; Ford, N. M.; Heckman, Timothy; Ji, Zhiyuan; Giavalisco, Mauro; Amorin, Ricardo (2022-05-01). "The Low-redshift Lyman Continuum Survey. I. New, Diverse Local Lyman Continuum Emitters". The Astrophysical Journal Supplement Series. 260 (1): 1. arXiv:2201.11716. Bibcode:2022ApJS..260....1F. doi:10.3847/1538-4365/ac5331. ISSN 0067-0049. S2CID 246294865.
  6. ^ Flury, Sophia R.; Jaskot, Anne E.; Ferguson, Harry C.; Worseck, Gábor; Makan, Kirill; Chisholm, John; Saldana-Lopez, Alberto; Schaerer, Daniel; McCandliss, Stephan R.; Xu, Xinfeng; Wang, Bingjie; Oey, M. S.; Ford, N. M.; Heckman, Timothy; Ji, Zhiyuan (2022-05-01). "The Low-redshift Lyman Continuum Survey. II. New Insights into LyC Diagnostics". The Astrophysical Journal. 930 (2): 126. arXiv:2203.15649. Bibcode:2022ApJ...930..126F. doi:10.3847/1538-4357/ac61e4. ISSN 0004-637X. S2CID 247778972.

April 09, 2024
lyman, continuum, photons, redirects, here, other, uses, disambiguation, abbrev, shortened, continuum, photons, photons, photons, emitted, from, stars, active, galactic, nuclei, photon, energies, above, lyman, limit, hydrogen, ionized, absorbing, working, from. LyC redirects here For other uses see LYC disambiguation Lyman continuum photons abbrev LyC shortened to Ly continuum photons or Lyc photons are the photons emitted from stars or active galactic nuclei at photon energies above the Lyman limit Hydrogen is ionized by absorbing LyC Working from Victor Schumann s discovery of ultraviolet light from 1906 to 1914 Theodore Lyman observed that atomic hydrogen absorbs light only at specific frequencies or wavelengths and the Lyman series is thus named after him 1 2 All the wavelengths in the Lyman series are in the ultraviolet band This quantized absorption behavior occurs only up to an energy limit known as the ionization energy In the case of neutral atomic hydrogen the minimum ionization energy is equal to the Lyman limit where the photon has enough energy to completely ionize the atom resulting in a free proton and a free electron Above this energy below this wavelength all wavelengths of light may be absorbed This forms a continuum in the energy spectrum the spectrum is continuous rather than composed of many discrete lines which are seen at lower energies 3 4 The Lyman SeriesThe Lyman limit is at the wavelength of 91 2 nm 912 A corresponding to a frequency of 3 29 million GHz and a photon energy of 13 6 eV 3 LyC energies are mostly in the ultraviolet C portion of the electromagnetic spectrum see Lyman series Although X rays and gamma rays will also ionize a hydrogen atom there are far fewer of them emitted from a star s photosphere LyC are predominantly UV C The photon absorption process leading to the ionization of atomic hydrogen can occur in reverse an electron and a proton can collide and form atomic hydrogen If the two particles were traveling slowly so that kinetic energy can be ignored then the photon the atom emits upon its creation will theoretically be 13 6 eV in reality the energy will be less if the atom is formed in an excited state At faster speeds the excess kinetic energy is radiated but momentum must be conserved as photons of lower wavelength higher energy Therefore photons with energies above 13 6 eV are emitted by the combination of energetic protons and electrons forming atomic hydrogen and emission from photoionized hydrogen See also editBalmer limit Lyman alpha blob Lyman alpha forest Lyman break galaxy Lyman series Haro 11 One of the two galaxies in the local universe that leaks Lyman continuum photons Tololo 1247 232 The second galaxy in the local universe that leaks Lyman continuum photons Pea galaxy Many nearby Green Peas are confirmed LyC leakers 5 6 ReionizationReferences edit Lyman Theodore 1906 The Spectrum of Hydrogen in the Region of Extremely Short Wave Length Memoirs of the American Academy of Arts and Sciences New Series 13 3 125 146 Bibcode 1906MAAAS 13 125L doi 10 2307 25058084 ISSN 0096 6134 JSTOR 25058084 In a preliminary paper1 the author has given the wave length of more than one hundred and thirty lines in the region of the spectrum lying between the values 1850 and 1030 tenth metres It is the object of the present paper to compare the results obtained by the author with those given by Schumann to describe the apparatus used in this research and to call attention to some new facts which have come to light since the publication of the first notice Lyman Theodore 1914 An Extension of the Spectrum in the Extreme Ultra Violet Nature 93 2323 241 Bibcode 1914Natur 93 241L doi 10 1038 093241a0 a b Dipankar Bhattacharya August December 2003 Matter and Radiation PDF Fundamentals of Astrophysics India Inter University Centre for Astronomy and Astrophysics In most situations the total emission by the free free process far exceeds the recombination radiation but the recombination radiation can introduce characteristic spectral features at ionisation thresholds in the continuum radiation For Hydrogen the highest ionisation threshold called the Lyman Limit corresponds to an energy of 13 6 eV or an wavelength of 912A Recombination radiation from Hydrogen at wavelengths shorter than this is called the Lyman continuum Lyman limit A Dictionary of Astronomy 1997 Archived from the original on May 23 2011 Lyman limit The short wavelength end of the hydrogen Lyman series at 91 2 nm It corresponds to the energy required for an electron in the hydrogen ground state to jump completely out of the atom leaving the atom ionized Flury Sophia R Jaskot Anne E Ferguson Harry C Worseck Gabor Makan Kirill Chisholm John Saldana Lopez Alberto Schaerer Daniel McCandliss Stephan Wang Bingjie Ford N M Heckman Timothy Ji Zhiyuan Giavalisco Mauro Amorin Ricardo 2022 05 01 The Low redshift Lyman Continuum Survey I New Diverse Local Lyman Continuum Emitters The Astrophysical Journal Supplement Series 260 1 1 arXiv 2201 11716 Bibcode 2022ApJS 260 1F doi 10 3847 1538 4365 ac5331 ISSN 0067 0049 S2CID 246294865 Flury Sophia R Jaskot Anne E Ferguson Harry C Worseck Gabor Makan Kirill Chisholm John Saldana Lopez Alberto Schaerer Daniel McCandliss Stephan R Xu Xinfeng Wang Bingjie Oey M S Ford N M Heckman Timothy Ji Zhiyuan 2022 05 01 The Low redshift Lyman Continuum Survey II New Insights into LyC Diagnostics The Astrophysical Journal 930 2 126 arXiv 2203 15649 Bibcode 2022ApJ 930 126F doi 10 3847 1538 4357 ac61e4 ISSN 0004 637X S2CID 247778972 Retrieved from https en wikipedia org w index php title Lyman continuum photons amp oldid 1213073075, wikipedia, wiki, book, books, library,

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