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Stellar mass

January 10, 2023

Stellar mass is a phrase that is used by astronomers to describe the mass of a star. It is usually enumerated in terms of the Sun's mass as a proportion of a solar mass (M☉). Hence, the bright star Sirius has around 2.02 M☉.[1] A star's mass will vary over its lifetime as mass is lost with the stellar wind or ejected via pulsational behavior, or if additional mass is accreted, such as from a companion star.

Properties

Stars are sometimes grouped by mass based upon their evolutionary behavior as they approach the end of their nuclear fusion lifetimes.

Very-low-mass stars with masses below 0.5 M☉ do not enter the asymptotic giant branch (AGB) but evolve directly into white dwarfs. (At least in theory; the lifetimes of such stars are long enough—longer than the age of the universe to date—that none has yet had time to evolve to this point and be observed.)

Low-mass stars with a mass below about 1.8–2.2 M☉ (depending on composition) do enter the AGB, where they develop a degenerate helium core.

Intermediate-mass stars undergo helium fusion and develop a degenerate carbon–oxygen core.

Massive stars have a minimum mass of 5–10 M☉. These stars undergo carbon fusion, with their lives ending in a core-collapse supernova explosion.[2] Black holes created as a result of a stellar collapse are termed stellar-mass black holes.

The combination of the radius and the mass of a star determines the surface gravity. Giant stars have a much lower surface gravity than main sequence stars, while the opposite is the case for degenerate, compact stars such as white dwarfs. The surface gravity can influence the appearance of a star's spectrum, with higher gravity causing a broadening of the absorption lines.[3]

Range

One of the most massive stars known is Eta Carinae,[4] with 100–200 M☉; its lifespan is very short—only several million years at most. A study of the Arches Cluster suggests that 150 M☉ is the upper limit for stars in the current era of the universe.[5][6][7] The reason for this limit is not precisely known, but it is partially due to the Eddington luminosity which defines the maximum amount of luminosity that can pass through the atmosphere of a star without ejecting the gases into space. However, a star named R136a1 in the RMC 136a star cluster has been measured at 215 M☉, putting this limit into question.[8][9] A study has determined that stars larger than 150 M☉ in R136 were created through the collision and merger of massive stars in close binary systems, providing a way to sidestep the 150 M☉ limit.[10]

The first stars to form after the Big Bang may have been larger, up to 300 M☉ or more,[11] due to the complete absence of elements heavier than lithium in their composition. This generation of supermassive, population III stars is long extinct, however, and currently only theoretical.

With a mass only 93 times that of Jupiter (MJ), or .09 M☉, AB Doradus C, a companion to AB Doradus A, is the smallest known star undergoing nuclear fusion in its core.[12] For stars with similar metallicity to the Sun, the theoretical minimum mass the star can have, and still undergo fusion at the core, is estimated to be about 75 MJ.[13][14] When the metallicity is very low, however, a recent study of the faintest stars found that the minimum star size seems to be about 8.3% of the solar mass, or about 87 MJ.[14][15] Smaller bodies are called brown dwarfs, which occupy a poorly defined grey area between stars and gas giants.

Change

The Sun is losing mass from the emission of electromagnetic energy and by the ejection of matter with the solar wind. It is expelling about (2–3)×10−14 M☉ per year.[16] The mass loss rate will increase when the Sun enters the red giant stage, climbing to (7–9)×10−14 M☉ y−1 when it reaches the tip of the red-giant branch. This will rise to 10−6 M☉ y−1 on the asymptotic giant branch, before peaking at a rate of 10−5 to 10−4 M☉ y−1 as the Sun generates a planetary nebula. By the time the Sun becomes a degenerate white dwarf, it will have lost 46% of its starting mass.[17]

References

  1. ^ Liebert, James; Young, Patrick A.; Arnett, David; Holberg, Jay B.; Williams, Kurtis A. (2005). "The Age and Progenitor Mass of Sirius B". The Astrophysical Journal. 630 (1): L69–L72. arXiv:astro-ph/0507523. Bibcode:2005ApJ...630L..69L. doi:10.1086/462419. S2CID 8792889.
  2. ^ Kwok, Sun (2000), The origin and evolution of planetary nebulae, Cambridge astrophysics series, vol. 33, Cambridge University Press, pp. 103–104, ISBN 0-521-62313-8.
  3. ^ Unsöld, Albrecht (2001), The New Cosmos (5th ed.), New York: Springer, pp. 180–185, 215–216, ISBN 3540678778.
  4. ^ Smith, Nathan (1998), "The Behemoth Eta Carinae: A Repeat Offender", Mercury Magazine, Astronomical Society of the Pacific, 27: 20, retrieved 2006-08-13.
  5. ^ "NASA's Hubble Weighs in on the Heaviest Stars in the Galaxy", NASA News, March 3, 2005, retrieved 2006-08-04.
  6. ^ Kroupa, P. (2005). "Stellar mass limited". Nature. 434 (7030): 148–149. doi:10.1038/434148a.
  7. ^ Figer, D.F. (2005). "An upper limit to the masses of stars". Nature. 434 (7030): 192–194. arXiv:astro-ph/0503193. doi:10.1038/nature03293.
  8. ^ Stars Just Got Bigger, European Southern Observatory, July 21, 2010, retrieved 2010-07-24.
  9. ^ Bestenlehner, Joachim M.; Crowther, Paul A.; Caballero-Nieves, Saida M.; Schneider, Fabian R. N.; Simon-Diaz, Sergio; Brands, Sarah A.; de Koter, Alex; Graefener, Goetz; Herrero, Artemio; Langer, Norbert; Lennon, Daniel J. (2020-10-17). "The R136 star cluster dissected with Hubble Space Telescope/STIS. II. Physical properties of the most massive stars in R136". Monthly Notices of the Royal Astronomical Society. 499 (2): 1918–1936. arXiv:2009.05136. doi:10.1093/mnras/staa2801. ISSN 0035-8711.
  10. ^ LiveScience.com, "Mystery of the 'Monster Stars' Solved: It Was a Monster Mash", Natalie Wolchover, 7 August 2012
  11. ^ Ferreting Out The First Stars, Harvard-Smithsonian Center for Astrophysics, September 22, 2005, retrieved 2006-09-05.
  12. ^ Weighing the Smallest Stars, ESO, January 1, 2005, retrieved 2006-08-13.
  13. ^ Boss, Alan (April 3, 2001), , Carnegie Institution of Washington, archived from the original on 2006-09-28, retrieved 2006-06-08.
  14. ^ a b Shiga, David (August 17, 2006), , New Scientist, archived from the original on 2006-11-14, retrieved 2006-08-23.
  15. ^ Hubble glimpses faintest stars, BBC, August 18, 2006, retrieved 2006-08-22.
  16. ^ Carroll, Bradley W.; Ostlie, Dale A. (1995), An Introduction to Modern Astrophysics (revised 2nd ed.), Benjamin Cummings, p. 409, ISBN 0201547309.
  17. ^ Schröder, K.-P.; Connon Smith, Robert (2008), "Distant future of the Sun and Earth revisited", Monthly Notices of the Royal Astronomical Society, 386 (1): 155–163, arXiv:0801.4031, Bibcode:2008MNRAS.386..155S, doi:10.1111/j.1365-2966.2008.13022.x

January 10, 2023
stellar, mass, phrase, that, used, astronomers, describe, mass, star, usually, enumerated, terms, mass, proportion, solar, mass, hence, bright, star, sirius, around, star, mass, will, vary, over, lifetime, mass, lost, with, stellar, wind, ejected, pulsational,. Stellar mass is a phrase that is used by astronomers to describe the mass of a star It is usually enumerated in terms of the Sun s mass as a proportion of a solar mass M Hence the bright star Sirius has around 2 02 M 1 A star s mass will vary over its lifetime as mass is lost with the stellar wind or ejected via pulsational behavior or if additional mass is accreted such as from a companion star Contents 1 Properties 2 Range 3 Change 4 ReferencesProperties EditStars are sometimes grouped by mass based upon their evolutionary behavior as they approach the end of their nuclear fusion lifetimes Very low mass stars with masses below 0 5 M do not enter the asymptotic giant branch AGB but evolve directly into white dwarfs At least in theory the lifetimes of such stars are long enough longer than the age of the universe to date that none has yet had time to evolve to this point and be observed Low mass stars with a mass below about 1 8 2 2 M depending on composition do enter the AGB where they develop a degenerate helium core Intermediate mass stars undergo helium fusion and develop a degenerate carbon oxygen core Massive stars have a minimum mass of 5 10 M These stars undergo carbon fusion with their lives ending in a core collapse supernova explosion 2 Black holes created as a result of a stellar collapse are termed stellar mass black holes The combination of the radius and the mass of a star determines the surface gravity Giant stars have a much lower surface gravity than main sequence stars while the opposite is the case for degenerate compact stars such as white dwarfs The surface gravity can influence the appearance of a star s spectrum with higher gravity causing a broadening of the absorption lines 3 Range EditOne of the most massive stars known is Eta Carinae 4 with 100 200 M its lifespan is very short only several million years at most A study of the Arches Cluster suggests that 150 M is the upper limit for stars in the current era of the universe 5 6 7 The reason for this limit is not precisely known but it is partially due to the Eddington luminosity which defines the maximum amount of luminosity that can pass through the atmosphere of a star without ejecting the gases into space However a star named R136a1 in the RMC 136a star cluster has been measured at 215 M putting this limit into question 8 9 A study has determined that stars larger than 150 M in R136 were created through the collision and merger of massive stars in close binary systems providing a way to sidestep the 150 M limit 10 The first stars to form after the Big Bang may have been larger up to 300 M or more 11 due to the complete absence of elements heavier than lithium in their composition This generation of supermassive population III stars is long extinct however and currently only theoretical With a mass only 93 times that of Jupiter MJ or 09 M AB Doradus C a companion to AB Doradus A is the smallest known star undergoing nuclear fusion in its core 12 For stars with similar metallicity to the Sun the theoretical minimum mass the star can have and still undergo fusion at the core is estimated to be about 75 MJ 13 14 When the metallicity is very low however a recent study of the faintest stars found that the minimum star size seems to be about 8 3 of the solar mass or about 87 MJ 14 15 Smaller bodies are called brown dwarfs which occupy a poorly defined grey area between stars and gas giants Change EditThe Sun is losing mass from the emission of electromagnetic energy and by the ejection of matter with the solar wind It is expelling about 2 3 10 14 M per year 16 The mass loss rate will increase when the Sun enters the red giant stage climbing to 7 9 10 14 M y 1 when it reaches the tip of the red giant branch This will rise to 10 6 M y 1 on the asymptotic giant branch before peaking at a rate of 10 5 to 10 4 M y 1 as the Sun generates a planetary nebula By the time the Sun becomes a degenerate white dwarf it will have lost 46 of its starting mass 17 References Edit Liebert James Young Patrick A Arnett David Holberg Jay B Williams Kurtis A 2005 The Age and Progenitor Mass of Sirius B The Astrophysical Journal 630 1 L69 L72 arXiv astro ph 0507523 Bibcode 2005ApJ 630L 69L doi 10 1086 462419 S2CID 8792889 Kwok Sun 2000 The origin and evolution of planetary nebulae Cambridge astrophysics series vol 33 Cambridge University Press pp 103 104 ISBN 0 521 62313 8 Unsold Albrecht 2001 The New Cosmos 5th ed New York Springer pp 180 185 215 216 ISBN 3540678778 Smith Nathan 1998 The Behemoth Eta Carinae A Repeat Offender Mercury Magazine Astronomical Society of the Pacific 27 20 retrieved 2006 08 13 NASA s Hubble Weighs in on the Heaviest Stars in the Galaxy NASA News March 3 2005 retrieved 2006 08 04 Kroupa P 2005 Stellar mass limited Nature 434 7030 148 149 doi 10 1038 434148a Figer D F 2005 An upper limit to the masses of stars Nature 434 7030 192 194 arXiv astro ph 0503193 doi 10 1038 nature03293 Stars Just Got Bigger European Southern Observatory July 21 2010 retrieved 2010 07 24 Bestenlehner Joachim M Crowther Paul A Caballero Nieves Saida M Schneider Fabian R N Simon Diaz Sergio Brands Sarah A de Koter Alex Graefener Goetz Herrero Artemio Langer Norbert Lennon Daniel J 2020 10 17 The R136 star cluster dissected with Hubble Space Telescope STIS II Physical properties of the most massive stars in R136 Monthly Notices of the Royal Astronomical Society 499 2 1918 1936 arXiv 2009 05136 doi 10 1093 mnras staa2801 ISSN 0035 8711 LiveScience com Mystery of the Monster Stars Solved It Was a Monster Mash Natalie Wolchover 7 August 2012 Ferreting Out The First Stars Harvard Smithsonian Center for Astrophysics September 22 2005 retrieved 2006 09 05 Weighing the Smallest Stars ESO January 1 2005 retrieved 2006 08 13 Boss Alan April 3 2001 Are They Planets or What Carnegie Institution of Washington archived from the original on 2006 09 28 retrieved 2006 06 08 a b Shiga David August 17 2006 Mass cut off between stars and brown dwarfs revealed New Scientist archived from the original on 2006 11 14 retrieved 2006 08 23 Hubble glimpses faintest stars BBC August 18 2006 retrieved 2006 08 22 Carroll Bradley W Ostlie Dale A 1995 An Introduction to Modern Astrophysics revised 2nd ed Benjamin Cummings p 409 ISBN 0201547309 Schroder K P Connon Smith Robert 2008 Distant future of the Sun and Earth revisited Monthly Notices of the Royal Astronomical Society 386 1 155 163 arXiv 0801 4031 Bibcode 2008MNRAS 386 155S doi 10 1111 j 1365 2966 2008 13022 x Retrieved from https en wikipedia org w index php title Stellar mass amp oldid 1096067562, wikipedia, wiki, book, books, library,

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