熱改正

在天文學中，熱改正是對天體絕對星等的改正值，以將天體的絕對目視星等轉換為熱星等（又稱全波段星等）。對於大部分輻射出射落在可見光範圍之外的恆星，熱改正的值將偏大。熱改正的統一尺度尚未標準化。

描述

熱改正的數學表達式為：

BC=M_{bol}-M_{v}\!\,

下表列出對具有不同光譜類型和分類的一系列恆星的熱改正： ^[1] ^[2] ^[3]

光譜型	主序星	巨星	超巨星
O3	-4.3	-4.2	-4.0
G0	-0.10	-0.13	-0.1
G5	-0.14	-0.34	-0.20
00	-0.24	-0.42	-0.38
K5	-0.66	-1.19	-1.00
M0	-1.21	-1.28	-1.3

對於早型星和晚型星，熱改正都為偏大的負數。前者是因為早型星表面溫度較高，輻射出射的很大一部分是在紫外波段的；後者則是因為晚型星表面溫度較低，輻射出射很大一部分在紅外波段。對於像我們的太陽這樣的恆星，熱改正是微不足道的，因為太陽的輻射出射集中在可見光波段。熱改正是對天體的絕對星等進行的校正，以將天體的絕對目視星等轉換為其熱星等。

類似的，熱改正可以用於可見光波段之外的其他電磁波段改正為熱星等。^[4]例如，對於某些領域內常見的輻射出射集中在紅外波段範圍內的、表面溫度較低的恆星，熱改正有時採用一套不同的值以改正紅外波段的絕對星等，而非絕對目視星等。

在數學上，這樣的改正值可以表示為：

BC_{K}=M_{bol}-M_{k}\!\,

^[5]

其中M _K是K波段的絕對星等， BC _K是K波段的熱改正值。 ^[6]

參見

外部連結

https://github.com/casaluca/bolometric-corrections （頁面存檔備份，存於互聯網檔案館） - most up to date tables of bolometric corrections across the HR diagram and interpolation routines in different photometric filters
https://web.archive.org/web/20080312151621/http://www.peripatus.gen.nz/Astronomy/SteMag.html - contains table of bolometric corrections
http://articles.adsabs.harvard.edu//full/1996ApJ...469..355F/0000360.000.html （頁面存檔備份，存於互聯網檔案館） - contains detailed tables of bolometric corrections (note that these second set of tables are consistent with a bolometric magnitude of 4.73 for the Sun and also be aware that there are misprint errors for a few of the figures in the tables)

參考文獻

^ Popper, Daniel M. Stellar Masses. Annual Review of Astronomy and Astrophysics. 1980-09-01, 18 (1): 115–164. Bibcode:1980ARA&A..18..115P. ISSN 0066-4146. doi:10.1146/annurev.aa.18.090180.000555.
^ Humphreys, R. M.; McElroy, D. B. The initial mass function for massive stars in the Galaxy and the Magellanic Clouds. The Astrophysical Journal. 1984, 284: 565–577. Bibcode:1984ApJ...284..565H. ISSN 0004-637X. doi:10.1086/162439 （英語）.
^ B., Kaler, James. Stars and their spectra : an introduction to the spectral sequence. Cambridge [Cambridgeshire]: Cambridge University Press. 1989. ISBN 978-0521304948. OCLC 17731797.
^ Bessell, M. S.; et al. Model atmospheres broad-band colors, bolometric corrections and temperature calibrations for O - M stars. Astronomy and Astrophysics. May 1998, 333: 231–250. Bibcode:1998A&A...333..231B.
^ Salaris, Maurizio; et al. Population effects on the red giant clump absolute magnitude: the K band. Monthly Notices of the Royal Astronomical Society. November 2002, 337 (1): 332–340. Bibcode:2002MNRAS.337..332S. arXiv:astro-ph/0208057  . doi:10.1046/j.1365-8711.2002.05917.x. Lower eﬀective temperatures correspond to higher values of $\scriptstyle BC_{K}$ ; since $\scriptstyle M_{K}=M_{bol}-BC_{K}\!\,$ , cooler RC stars tend to be brighter.
^ Buzzoni, A.; et al. Bolometric correction and spectral energy distribution of cool stars in Galactic clusters. Monthly Notices of the Royal Astronomical Society. April 2010, 403 (3): 1592–1610 [23 August 2015]. Bibcode:2010MNRAS.403.1592B. arXiv:1002.1972  . doi:10.1111/j.1365-2966.2009.16223.x.

[1] Popper, Daniel M. Stellar Masses. Annual Review of Astronomy and Astrophysics. 1980-09-01, 18 (1): 115–164. Bibcode:1980ARA&A..18..115P. ISSN 0066-4146. doi:10.1146/annurev.aa.18.090180.000555.

[2] Humphreys, R. M.; McElroy, D. B. The initial mass function for massive stars in the Galaxy and the Magellanic Clouds. The Astrophysical Journal. 1984, 284: 565–577. Bibcode:1984ApJ...284..565H. ISSN 0004-637X. doi:10.1086/162439 （英語）.

[3] B., Kaler, James. Stars and their spectra : an introduction to the spectral sequence. Cambridge [Cambridgeshire]: Cambridge University Press. 1989. ISBN 978-0521304948. OCLC 17731797.

[4] Bessell, M. S.; et al. Model atmospheres broad-band colors, bolometric corrections and temperature calibrations for O - M stars. Astronomy and Astrophysics. May 1998, 333: 231–250. Bibcode:1998A&A...333..231B.

[nonredclumpSalaris2002-5] Salaris, Maurizio; et al. Population effects on the red giant clump absolute magnitude: the K band. Monthly Notices of the Royal Astronomical Society. November 2002, 337 (1): 332–340. Bibcode:2002MNRAS.337..332S. arXiv:astro-ph/0208057  . doi:10.1046/j.1365-8711.2002.05917.x. Lower eﬀective temperatures correspond to higher values of $\scriptstyle BC_{K}$ ; since $\scriptstyle M_{K}=M_{bol}-BC_{K}\!\,$ , cooler RC stars tend to be brighter.

[nonstandardphotography2010-6] Buzzoni, A.; et al. Bolometric correction and spectral energy distribution of cool stars in Galactic clusters. Monthly Notices of the Royal Astronomical Society. April 2010, 403 (3): 1592–1610 [23 August 2015]. Bibcode:2010MNRAS.403.1592B. arXiv:1002.1972  . doi:10.1111/j.1365-2966.2009.16223.x.

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