page_title: Yellow supergiant star
section_title: Properties
hierarchical_section_title: Yellow supergiant star / Properties
caption_attribution_description: English: The sky is a jewelry box full of sparkling stars in these infrared images. The crown jewels are 14 massive stars on the verge of exploding as supernovae. These hefty stars reside in one of the most massive star clusters in the Milky Way Galaxy. The bluish cluster is inside the white box in the large image, which shows the star-studded region around it. A close-up of the cluster can be seen in the inset photo. These large stars are a tip-off to the mass of the young cluster. Astronomers estimate that the cluster is at least 20,000 times as massive as the Sun. Each red supergiant is about 20 times the Sun's mass. The larger color-composite image was taken by the Spitzer Space Telescope for the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) Legacy project. The survey penetrates obscuring dust along the thick disk of our galaxy to reveal never-before-seen stars and star clusters. The false colors in the image correspond to infrared-light emission. The stars in the large color-composite image all appear blue because they emit most of their infrared light at shorter wavelengths. The inset image, a false-color composite, was captured by the Two Micron All Sky Survey (2MASS). Astronomers identified the cluster as a potential behemoth after spotting it in the 2MASS catalogue. They then used the Infrared Multi-object Spectrograph at the Kitt Peak National Observatory in Arizona to analyze the cluster's colors. From that analysis, they discovered the red supergiants. They confirmed the red supergiants' pedigree by studying the colors of other red supergiants in data taken by the Spitzer Space Telescope. The cluster lies 18,900 light-years away in the direction of the constellation Scutum. It is the first in a survey of 130 potentially massive star clusters in the Milky Way that astronomers will study over the next five years using a variety of telescopes, including the Spitzer and Hubble space telescopes. The Spitzer image was taken April 4, 2004; the 2MASS image on July 4, 1999. The science team that studied the star cluster consists of Don Figer, Space Telescope Science Institute/Rochester Institute of Techology; John MacKenty, Massimo Robberto, and Kester Smith, Space Telescope Science Institute; Francisco Najarro, Instituto de Estructura de la Materia in Madrid, Spain: Rolf Kudritzki, University of Hawaii in Honolulu; and Artemio Herrero, Universidad de La Laguna in Tenerife, Spain.
context_page_description: A yellow supergiant is a star, generally of spectral type F or G, having a supergiant luminosity class. They are stars that have evolved away from the main sequence, expanding and becoming more luminous.
  Yellow supergiants are smaller than red supergiants; naked eye examples include Canopus and Polaris. Many of them are variable stars, mostly pulsating Cepheids such as δ Cephei itself.
context_section_description: Yellow supergiants have a relatively narrow range of temperatures corresponding to their spectral types, from about 4,000 K to 7,000 K.  Their luminosities range from about 1,000 L☉ upwards, with the most luminous stars exceeding 100,000 L☉.  The high luminosities indicate that they are much larger than the sun, from about 30 R☉ to several hundred R☉.
  The masses of yellow supergiants vary greatly, from less than the sun for stars such as W Virginis to 20 M☉ or more (e.g. V810 Centauri).  Corresponding surface gravities (log(g) cgs) are around 1–2 for high-mass supergiants, but can be as low as 0 for low-mass supergiants.
  Yellow supergiants are rare stars, much less common than red supergiants and main sequence stars.  In M31 (Andromeda Galaxy), 16 yellow supergiants are seen associated with evolution from class O stars, of which there are around 25,000 visible.
caption: The massive RSGC1 cluster contains 14 red supergiants and one yellow supergiant.[8]
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