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<h2 id="quantitative-color-index-terms">Quantitative color index terms</h2> Quantitative color index terms<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a><table><tbody><tr><th>Color(Vega reference)</th><th>Color index(B-V)</th><th>Spectral class(<a href="/facts/Main_sequence/DJ3Wq8kd">main sequence</a>)</th><th>Spectral class(<a href="/facts/Giant_star/kMseY7qf">giant stars</a>)</th><th>Spectral class(<a href="/facts/Supergiant_stars/y7w8WEcm">supergiant stars</a>)</th><th>Examples </th></tr><tr><td>Red</td><td>≥1.40</td><td>M</td><td>K4-M9</td><td>K3-M9</td><td><a href="/facts/Betelgeuse/BsD9Ap7C">Betelgeuse</a>, <a href="/facts/Antares/adRhtq7X">Antares</a></td></tr><tr><td>Orange</td><td>0.80-1.40</td><td>K</td><td>G4-K3</td><td>G1-K2</td><td><a href="/facts/Arcturus/8W0qslPJ">Arcturus</a>, <a href="/facts/Pollux_(star)/Gv5T0K3a">Pollux</a></td></tr><tr><td>Yellow</td><td>0.60-0.80</td><td>G</td><td>G0-G3</td><td>F8-G0</td><td><a href="/facts/Sun/CadPCVHh">Sun</a>, <a href="/facts/Rigil_Kent/6BlySfIj">Rigil Kent</a></td></tr><tr><td>Green</td><td>0.30-0.60</td><td>F</td><td>F</td><td>F4-7</td><td><a href="/facts/Procyon/43Nou3on">Procyon</a></td></tr><tr><td>White</td><td>0.00-0.30</td><td>A</td><td>A</td><td>A0-F3</td><td><a href="/facts/Sirius/sHCkClse">Sirius</a>, <a href="/facts/Vega/G3wJwhhl">Vega</a></td></tr><tr><td>Blue</td><td>-0.33-0.00</td><td>OB</td><td>OB</td><td>OB</td><td><a href="/facts/Spica/bqWfSvp5">Spica</a>, <a href="/facts/Rigel/WeeIXAAv">Rigel</a></td></tr></tbody></table> <p>The common color labels (e.g. red supergiant) are subjective and taken using the star Vega as the reference. However, these labels, which have a quantifiable basis, do not reflect how the human eye would perceive the colors of these stars. For instance, Vega has a bluish white color, while the Sun, from outer space, would look like a neutral white somewhat warmer than the <a href="/facts/Illuminant_D65/5bzuVsKc">illuminant D65</a> (which may be considered a slightly cool white). "Green" stars would be perceived as white by the human eye. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Asteroid_color_indices/WoSTAYnh">Asteroid color indices</a></li> <li><a href="/facts/Color%25E2%2580%2593color_diagram/NfWb5r2Y">Color–color diagram</a></li> <li><a href="/facts/Distant_object_color_indices/oF5vsbz9">Distant object color indices</a></li> <li><a href="/facts/Spectral_index/JEUttYWM">Spectral index</a></li> <li><a href="/facts/UBV_photometric_system/eoJL34eN">UBV photometric system</a></li> <li><a href="/facts/Zero_point_(photometry)/u0Eto333">Zero point</a></li></ul> <h2 id="notes">Notes</h2> <h2 id="further-reading">Further reading</h2> <ul><li><a href="http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1953ApJ...117..313J&db_key=AST&high=3c321cbf8303780">Query</a> for <a href="/facts/Harold_Johnson_(astronomer)/I6NLRuhS">Johnson, H. L.</a> and <a href="/facts/William_Wilson_Morgan/bsLDEwyS">Morgan</a>, ApJ 117, 313 (1953)</li> <li><a href="http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1974MNRAS.166..711C&db_key=AST&high=3c321cbf8304063">Query</a> for <a href="/facts/Alan_William_James_Cousins/kkr7QWjS">Cousins, A. W. J.</a>, MNRAS 166, 711 (1974)</li> <li><a href="http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1974MNSSA..33..149C&db_key=AST&high=3c321cbf8304063">Query</a> for <a href="/facts/Alan_William_James_Cousins/kkr7QWjS">Cousins, A. W. J.</a>, MNASSA 33, 149 (1974)</li> <li><a href="http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1990PASP..102.1181B&db_key=AST&high=3c321cbf8304649">Query</a> for Bessell, M. S., PASP 102, 1181 (1990)</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Zombeck, Martin V. (1990). "Calibration of MK spectral types". Handbook of Space Astronomy and Astrophysics (2nd ed.). Cambridge University Press. p. 105. ISBN 0-521-34787-4. <a href="0-521-34787-4" target="_blank">0-521-34787-4</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>David F. Gray (1992), The Inferred Color Index of the Sun, Publications of the Astronomical Society of the Pacific, vol. 104, no. 681, pp. 1035–1038 (November 1992). <a href="http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1992PASP..104.1035G&db_key=AST&data_type=HTML&format=&high=44b52c369023103" target="_blank">http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1992PASP..104.1035G&db_key=AST&data_type=HTML&format=&high=44b52c369023103</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"* bet Ori". SIMBAD. Centre de données astronomiques de Strasbourg. <a href="http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+bet+Ori" target="_blank">http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+bet+Ori</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Murdin, P., ed. (2001). "Tycho Star Catalogs: The 2.5 Million Brightest Stars". Encyclopedia of Astronomy & Astrophysics. Boca Raton: CRC Press. doi:10.1888/0333750888/2862. ISBN 978-1-003-22043-5. <a href="978-1-003-22043-5" target="_blank">978-1-003-22043-5</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"VizieR". webviz.u-strasbg.fr. Retrieved 2024-04-02. <a href="http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/50/catalog&recno=1607" target="_blank">http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/50/catalog&recno=1607</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Maki Sekiguchi and Masataka Fukugita (2000). "A Study of the B−V Color-Temperature Relation". Astrophysical Journal. 120 (2): 1072. doi:10.1086/301490. <a href="https://doi.org/10.1086%2F301490" target="_blank">https://doi.org/10.1086%2F301490</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Ballesteros, F. J. (2012). "New insights into black bodies". EPL. 97 (3). 34008. arXiv:1201.1809. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>BallesterosBV_T API http://www.hs.uni-hamburg.de/DE/Ins/Per/Czesla/PyA/PyA/index.html. <a href="http://www.hs.uni-hamburg.de/DE/Ins/Per/Czesla/PyA/PyA/index.html" target="_blank">http://www.hs.uni-hamburg.de/DE/Ins/Per/Czesla/PyA/PyA/index.html</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Landolt, Arlo U. (1992-07-01). "UBVRI Photometric Standard Stars in the Magnitude Range 11.5 < V < 16.0 Around the Celestial Equator". The Astronomical Journal. 104: 340. Bibcode:1992AJ....104..340L. doi:10.1086/116242. ISSN 0004-6256. <a href="https://ui.adsabs.harvard.edu/abs/1992AJ....104..340L" target="_blank">https://ui.adsabs.harvard.edu/abs/1992AJ....104..340L</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Michael S. Bessell (1990), UBVRI passbands, Publications of the Astronomical Society of the Pacific, vol. 102, Oct. 1990, p. 1181–1199. <a href="http://adsabs.harvard.edu/abs/1990PASP..102.1181B" target="_blank">http://adsabs.harvard.edu/abs/1990PASP..102.1181B</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Pace, G. (February 15, 1971), UBV: Subroutine to Compute Photometric Magnitudes of the Planets and Their Satellites (PDF) (Technical report), Jet Propulsion Laboratory <a href="https://ntrs.nasa.gov/api/citations/19710009758/downloads/19710009758.pdf" target="_blank">https://ntrs.nasa.gov/api/citations/19710009758/downloads/19710009758.pdf</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Neuhäuser, R; Torres, G; Mugrauer, M; Neuhäuser, D L; Chapman, J; Luge, D; Cosci, M (2022-07-29). "Colour evolution of Betelgeuse and Antares over two millennia, derived from historical records, as a new constraint on mass and age". Monthly Notices of the Royal Astronomical Society. 516 (1): 693–719. arXiv:2207.04702. Bibcode:2022MNRAS.516..693N. doi:10.1093/mnras/stac1969. ISSN 0035-8711. <a href="https://doi.org/10.1093%2Fmnras%2Fstac1969" target="_blank">https://doi.org/10.1093%2Fmnras%2Fstac1969</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Neuhäuser, R; Torres, G; Mugrauer, M; Neuhäuser, D L; Chapman, J; Luge, D; Cosci, M (2022-07-29). "Colour evolution of Betelgeuse and Antares over two millennia, derived from historical records, as a new constraint on mass and age". Monthly Notices of the Royal Astronomical Society. 516 (1): 693–719. arXiv:2207.04702. Bibcode:2022MNRAS.516..693N. doi:10.1093/mnras/stac1969. ISSN 0035-8711. <a href="https://doi.org/10.1093%2Fmnras%2Fstac1969" target="_blank">https://doi.org/10.1093%2Fmnras%2Fstac1969</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> </ol>