Qué (quién) es S-type star - definición
S-type star
![TP-AGB]] to become an S star and then a [[carbon star]]<ref name=weiss/>](https://commons.wikimedia.org/wiki/Special:FilePath/Evolution on the TP-AGB.png?width=200 "TP-AGB]] to become an S star and then a [[carbon star]]<ref name=weiss/>")
![PIONIER]] on the VLT](https://commons.wikimedia.org/wiki/Special:FilePath/The surface of the red giant star π1 Gruis from PIONIER on the VLT.jpg?width=200 "PIONIER]] on the VLT")
COOL GIANT WITH APPROXIMATELY EQUAL QUANTITIES OF CARBON AND OXYGEN IN ITS ATMOSPHERE
Extrinsic S-type star; Intrinsic S star; Extrinsic S star; MS star (spectral type)
An S-type star (or just S star) is a cool giant with approximately equal quantities of carbon and oxygen in its atmosphere. The class was originally defined in 1922 by Paul Merrill for stars with unusual absorption lines and molecular bands now known to be due to s-process elements.
O-type star
![The [[Trifid Nebula]] (M20) is sculpted and lit by the luminous O7.5III star visible at its centre in this infrared image.](https://commons.wikimedia.org/wiki/Special:FilePath/M20 nebula.jpg?width=200 "The [[Trifid Nebula]] (M20) is sculpted and lit by the luminous O7.5III star visible at its centre in this infrared image.")
![Alnitak is a triple star system with an O9.7 supergiant and an O9 giant as well as a B0 giant. These stars illuminate the nearby [[Flame Nebula]].](https://commons.wikimedia.org/wiki/Special:FilePath/Ngc2024 2mass.jpg?width=200 "Alnitak is a triple star system with an O9.7 supergiant and an O9 giant as well as a B0 giant. These stars illuminate the nearby [[Flame Nebula]].")
![Structure of low-mass, intermediate-mass, and high-mass stars. M indicates [[solar mass]]es.](https://commons.wikimedia.org/wiki/Special:FilePath/Star types.svg?width=200 "Structure of low-mass, intermediate-mass, and high-mass stars. M indicates [[solar mass]]es.")
![The brightest star in the [[Trapezium cluster]] is O7V star θ1 Orionis C. The other three are B0.5 and B1 main-sequence stars.](https://commons.wikimedia.org/wiki/Special:FilePath/Trapezium cluster optical and infrared comparison.jpg?width=200 "The brightest star in the [[Trapezium cluster]] is O7V star θ1 Orionis C. The other three are B0.5 and B1 main-sequence stars.")
STELLAR CLASSIFICATION
O star; Type-O star; O-type Stars; O-type stars
An O-type star is a hot, blue-white star of spectral type O in the Yerkes classification system employed by astronomers. They have temperatures in excess of 30,000 kelvin (K).
Carbon star
![Echelle spectra]] of the carbon star [[UU Aurigae]]](https://commons.wikimedia.org/wiki/Special:FilePath/Echelle Spectra of the Carbon Star UU Aurigae.jpg?width=200 "Echelle spectra]] of the carbon star [[UU Aurigae]]")
![LMC]] carbon stars with a given near-infrared luminosity. The median value is marked in red. Adapted from Ripoche ''et al.'' (2020)<ref name="RipocheMNRAS495"/>](https://commons.wikimedia.org/wiki/Special:FilePath/LMCCarbonStarPDF.png?width=200 "LMC]] carbon stars with a given near-infrared luminosity. The median value is marked in red. Adapted from Ripoche ''et al.'' (2020)<ref name=\"RipocheMNRAS495\"/>")
STAR WHOSE ATMOSPHERE CONTAINS MORE CARBON THAN OXYGEN
Carbon Star; Type-C stars; Carbon stars; N star; H star; Hd star; Carbon Stars; C star; Oxygen star; C-type star; Carbon giant; Type-R star
A carbon star (C-type star) is typically an asymptotic giant branch star, a luminous red giant, whose atmosphere contains more carbon than oxygen. The two elements combine in the upper layers of the star, forming carbon monoxide, which consumes most of the oxygen in the atmosphere, leaving carbon atoms free to form other carbon compounds, giving the star a "sooty" atmosphere and a strikingly ruby red appearance.
