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Below is a list of the largest stars currently known, ordered by radius. The unit of measurement used is the radius of the Sun (approximately 695,700 km; 432,300 mi). The angular diameters of stars can be measured directly using stellar interferometry. Other methods can use lunar occultations or from eclipsing binaries, which can be used to test indirect methods of finding stellar radii. Only a few useful supergiant stars can be occulted by the Moon, including Antares A (Alpha Scorpii A). Examples of eclipsing binaries are Epsilon Aurigae (Almaaz), VV Cephei, and V766 Centauri (HR 5171). Angular diameter measurements can be inconsistent because the boundary of the very tenuous atmosphere (opacity) differs depending on the wavelength of light in which the star is observed. Uncertainties remain with the membership and order of the list, especially when deriving various parameters used in calculations, such as stellar luminosity and effective temperature. Often stellar radii can only be expressed as an average or be within a large range of values. Values for stellar radii vary significantly in different sources and for different observation methods. All the sizes stated in this list have various inaccuracies and may be disputed. This list is still a work in progress and various parameters are extremely disputed.
Various issues exist in determining accurate radii of the largest stars, which in many cases do display significant errors. The following lists are generally based on various considerations or assumptions; these include:
Star name | Solar radii (Sun = 1) |
Method[3] | Notes |
---|---|---|---|
LGGS J004539.99+415404.1 | 1,980[4]–2,377[5] | L/Teff | Located in the Andromeda Galaxy |
Orbit of Saturn | 1,940–2,169 | Reported for reference | |
MSX LMC 597 (W60 A27) | 1,882–1,953[6] | L/Teff | Located in the Large Magellanic Cloud |
LGGS J004520.67+414717.3 | 1,870[4]–2,510[5] | L/Teff | Located in the Andromeda Galaxy |
UY Scuti | 1,708 ± 192[7] | AD | This value was based on an angular diameter and distance of 2.9 kpc. Gaia Data Release 2 suggests a distance of 1.55 kpc and a consequently smaller radius of 755 R☉.[8] However, the Gaia parallax is considered unreliable (until further observations) due to a very high level of astrometric noise.[9] |
LGGS J003919.11+404319.2 | 1,685[10] | L/Teff | Located in the Andromeda Galaxy |
WOH S71 (LMC 23095) | 1,662[11]–1,896[2] | L/Teff | Located in the Large Magellanic Cloud |
HV 2242 (WOH S69) | 1,645[2] | L/Teff | Located in the Large Magellanic Cloud |
LGGS J013339.28+303118.8 | 1,565[12]–1,863[5] | L/Teff | Located in the Triangulum Galaxy |
WOH G64 | 1,540 ± 77[13][14] | L/Teff | Located in the Large Magellanic Cloud |
LGGS J013312.26+310053.3 | 1,537[12]–1,765[5] | L/Teff | Located in the Triangulum Galaxy |
MSX LMC 1204 (WOH S72) | 1,537–1,709[6] | L/Teff | Located in the Large Magellanic Cloud |
W61 8-88 (WOH S465) | 1,491[2] | L/Teff | Located in the Large Magellanic Cloud |
HV 888 (WOH S140) | 1,477[15]–1,974[16] | L/Teff | Located in the Large Magellanic Cloud. Another recent estimate gives 1,765 R☉.[2] |
UCAC4 116-007944 (MSX LMC 810) | 1,468[2] | L/Teff | Located in the Large Magellanic Cloud |
W60 A78 (WOH S459) | 1,445[2] | L/Teff | Located in the Large Magellanic Cloud |
HV 12998 (WOH S369) | 1,443[2] | L/Teff | Located in the Large Magellanic Cloud |
W60 A72 (WOH S453) | 1,441[2] | L/Teff | Located in the Large Magellanic Cloud |
VY Canis Majoris | 1,420 ± 120[17][18] | AD | Used to be described as the largest known star based on a radius of 1,800–2,100 R☉.[19] Older estimates gave the radius of VY CMa as above 3,000 R☉,[20] or as little as 600 R☉.[21] Matsuura et al. 2013 estimates 2,069 R☉ based on a luminosity of 237,000 L☉ and an assumed effective temperature of 2,800 K.[22][23] |
WOH S286 | 1,417[2] | L/Teff | Located in the Large Magellanic Cloud |
AH Scorpii | 1,411 ± 124[7] | AD | AH Sco is a variable by nearly 3 magnitudes in the visual range, and an estimated 20% in luminosity. The variation in diameter is not clear because the temperature also varies. |
LGGS J004428.48+415130.9 | 1,410[4]–1,504[5] | L/Teff | Located in the Andromeda Galaxy |
MG73 46 (MSX LMC 891) | 1,385[16]–1,838[2] | L/Teff | Located in the Large Magellanic Cloud |
WOH S281 (IRAS 05261-6614) | 1,376[24]–1,459[2] | L/Teff | Located in the Large Magellanic Cloud |
IRAS 05280-6910 | 1,367[11]–1,738[25] | L/Teff | Located in the Large Magellanic Cloud |
S Persei | 1,364 ± 6[26] | AD | A red supergiant located in the Perseus Double Cluster. Levesque et al. 2005 calculated radii of 780 R☉ and 1,230 R☉ based on K-band measurements.[27] Older estimates gave up to 2,853 R☉ based on higher luminosities.[28] |
PHL 293B | 1,348–1,463[29] | L/Teff | A luminous blue variable star located in the low metallicity galaxy PHL 293B. It is thought to have disappeared. |
LGGS J013414.27+303417.7 | 1,342[12]–1,953[5] | L/Teff | Located in the Triangulum Galaxy |
HV 5993 (WOH S464) | 1,319[16]–1,531[2] | L/Teff | Located in the Large Magellanic Cloud |
SW Cephei | 1,308[30] | AD | |
Stephenson 2 DFK 2 | 1,301[31] | L/Teff | Located in the massive open cluster Stephenson 2. |
Stephenson 2 DFK 49 | 1,300[31] | L/Teff | Located in the massive open cluster Stephenson 2. |
LGGS J004312.43+413747.1 | 1,270[4]–1,630[5] | L/Teff | Located in the Andromeda Galaxy |
LGGS J004514.91+413735.0 | 1,250[4]–1,575[5] | L/Teff | Located in the Andromeda Galaxy |
LGGS J004428.12+415502.9 | 1,240[4]–1,259[5] | L/Teff | Located in the Andromeda Galaxy |
IRAS 05346-6949 | 1,211[13]–2,064[6] | L/Teff | Located in the Large Magellanic Cloud |
LGGS J004125.23+411208.9 | 1,200[4]–1,602[5] | L/Teff | Located in the Andromeda Galaxy |
HD 90587 | 1,191[30] | AD | |
NML Cygni | 1,183[32] | L/Teff | |
LGGS J004524.97+420727.2 | 1,170[4]–1,476[5] | L/Teff | Located in the Andromeda Galaxy |
Westerlund 1-26 | 1,165–1,221[33] | L/Teff | Very uncertain parameters for an unusual star with strong radio emission. The spectrum is variable but apparently the luminosity is not.
|
W60 B90 (WOH S264) | 1,149[24]–2,555[2] | L/Teff | Located in the Large Magellanic Cloud |
HD 62745 | 1,145[30] | AD | |
LGGS J004047.22+404445.5 | 1,140[4]–1,379[5] | L/Teff | Located in the Andromeda Galaxy |
LGGS J004035.08+404522.3 | 1,140[4]–1,354[5] | L/Teff | Located in the Andromeda Galaxy |
MY Cephei | 1,134[34]–2,061[35] | L/Teff | Not to be confused with Mu Cephei (see below). Older estimates have given up to 2,440 R☉ based on much cooler temperatures.[36] |
LGGS J004124.80+411634.7 | 1,130[4]–1,423[5] | L/Teff | Located in the Andromeda Galaxy |
ST Cephei | 1,109[30] | AD | |
HD 102115 | 1,100[30] | AD | |
LGGS J004107.11+411635.6 | 1,100[4]–1,207[5] | L/Teff | Located in the Andromeda Galaxy |
LGGS J004031.00+404311.1 | 1,080[4]–1,383[5] | L/Teff | Located in the Andromeda Galaxy |
V366 Andromedae | 1,076[30] | AD | |
Trumpler 27-1 | 1,073[8] | L/Teff | Located in the massive possible open cluster Trumpler 27 |
LGGS J004531.13+414825.7 | 1,070[4]–1,420[5] | L/Teff | Located in the Andromeda Galaxy |
IM Cassiopeiae | 1,068[30] | AD | |
Orbit of Jupiter | 1,064–1,173 | Reported for reference
|
|
HR 5171 Aa (V766 Centauri Aa) | 1,060–1,160[37] | L/Teff | |
SU Persei | 1,048[30] | AD |
|
LGGS J004114.18+403759.8 | 1,040[4]–1,249[5] | L/Teff | Located in the Andromeda Galaxy |
AS Cephei | 1,026[30] | AD | |
LGGS J004125.72+411212.7 | 1,020[4]–1,359[5] | L/Teff | Located in the Andromeda Galaxy |
LGGS J004059.50+404542.6 | 1,020[4]–1,367[5] | L/Teff | Located in the Andromeda Galaxy |
HD 167861 | 1,016[30] | AD | |
HV 986 (WOH S368) | 1,010[39] | L/Teff | Located in the Large Magellanic Cloud |
The following stars with sizes below 1,000 solar radii are shown for comparison. | |||
CZ Hydrae | 986[40] | L/Teff | One of the coolest stars at 2000 K.[40] |
Mu Cephei (Herschel's "Garnet Star") | 972 ± 228[41] | L/Teff | Prototype of the obsolete class of the Mu Cephei variables and also one of reddest stars in the night sky in terms of the B-V color index.[42] Other estimates have given as high as 1,650 R☉ based on angular diameter.[43] |
V602 Carinae | 932[8]–1,151[30] | AD | |
Betelgeuse (Alpha Orionis) | 764+116 −62[44] |
AD | Star with the third largest apparent size after R Doradus and the Sun. Brightest red supergiant in the night sky. Another estimate gives 955±217 R☉[45] |
Antares A (Alpha Scorpii A) | 707[30] | AD | Antares was originally calculated to be over 850 R☉,[46][47] but those estimates are likely to have been affected by asymmetry of the atmosphere of the star.[48] |
V354 Cephei | 685[8] | L/Teff | |
KY Cygni | 672[8]–1,420[27][49] | L/Teff | |
Orbit of Ceres | 595 (550–641) | Reported for reference | |
119 Tauri (CE Tauri) | 587–593[50] | AD | Can be occulted by the Moon, allowing accurate determination of its apparent diameter. |
CW Leonis | 580–686[51] | L/Teff | Prototype of carbon stars. CW Leo was mistakenly identified as the claimed planet "Nibiru" or "Planet X". |
Mira A (Omicron Ceti) | 541[32] | AD | Prototype Mira variable. De beck et al. 2010 calculates 541 R☉.[32] |
VV Cephei A | 516[52]–1,000[53] | EB | VV Cep A is a highly distorted star in a close binary system, losing mass to the secondary for at least part of its orbit. Data from the most recent eclipse has cast additional doubt on the accepted model of the system. Older estimates give up to 1,900 R☉[27] |
V382 Carinae (x Carinae) | 485 ± 40[54] | AD | Yellow hypergiant, one of the rarest types of a star. |
Pistol Star | 435[55] | AD | Blue hypergiant, among the most massive and luminous stars known. |
HD 179821 | 400–450[37] | DSKE | V1427 Aquilae may be a yellow hypergiant or a much less luminous star. |
V509 Cassiopeiae | 390–910[56] | AD | Yellow hypergiant, one of the rarest types of a star. |
Inner limits of the asteroid belt | 380 | Reported for reference | |
IRC +10420 | 380[57] | L/Teff | A yellow hypergiant that has increased its temperature into the LBV range. De beck et al. 2010 calculates 1,342 R☉ based on a much cooler temperature.[32] |
V688 Monocerotis | 372[40] | L/Teff | Also one of the coolest stars at 2000 K.[40] |
R Doradus | 298 ± 21[58] | AD | Star with the second largest apparent size after the Sun. |
Orbit of Mars | 297–358 | Reported for reference | |
La Superba (Y Canum Venaticorum) | 289[30]–352[59] | AD and L/Teff | Referred to as La Superba by Angelo Secchi. Currently one of the coolest and reddest stars. |
Sun's red giant phase | 256[60] | At this point, the Sun will engulf Mercury and Venus, and possibly the Earth although it will move away from its orbit since the Sun will lose a third of its mass. During the helium burning phase, it will shrink to 10 R☉ but will later grow again and become an unstable AGB star, and then a white dwarf after making a planetary nebula.[61][62] Reported for reference | |
Rho Cassiopeiae | 242[30] | AD | Yellow hypergiant, one of the rarest types of a star. |
Eta Carinae A | ~240[63] | Previously thought to be the most massive single star, but in 2005 it was realized to be a binary system. During the Great Eruption, the size was much larger at around 1,400 R☉.[64] η Car is calculated to be between 60 R☉ and 881 R☉.[65] | |
Orbit of Earth | 215(211–219) | Reported for reference | |
Solar System Habitable Zone | 200–520[66] (uncertain) | Reported for reference | |
Orbit of Venus | 154–157 | Reported for reference | |
Epsilon Aurigae A (Almaaz A) | 143–358[67] | AD | ε Aurigae was incorrectly claimed in 1970 as the largest star with a size between 2,000 R☉ and 3,000 R☉,[68] even though it later turned out not to be an infrared light star but rather a dusk torus surrounding the system. |
Deneb (Alpha Cygni) | 99.84[30] | AD | Prototype Alpha Cygni variable. |
Peony Star | 92[69] | AD | Candidate for most luminous star in the Milky Way. |
Canopus (Alpha Carinae) | 71[70] | AD | Second brightest star in the night sky. |
Orbit of Mercury | 66–100 | Reported for reference | |
LBV 1806-20 | 46–145[71] | L/Teff | Formerly a candidate for the most luminous star in the Milky Way with 40 million L☉,[72] but the luminosity has been revised later only 2 million L☉.[73][74] |
Aldebaran (Alpha Tauri) | 44.13 ± 0.84[75] | AD | Fourteenth brightest star in the night sky |
R136a1 | 39.2[76] | L/Teff | Also on record as one of the most massive and luminous stars known (215 M☉ and 6.2 million L☉). |
Polaris (Alpha Ursae Minoris) | 37.5[77] | AD | The current northern pole star. |
Arcturus (Alpha Boötis) | 24.25[30] | AD | Brightest star in the northern celestial hemisphere. |
HDE 226868 | 20–22[78] | The supergiant companion of black hole Cygnus X-1. The black hole is around 500,000 times smaller than the star. | |
Sun | 1 | The largest object in the Solar System. Reported for reference |