List of largest stars

Relative sizes of the planets in the Solar System and some of the largest stars:

1. Mercury < Mars < Venus < Earth
2. Earth < Neptune < Uranus < Saturn < Jupiter
3. Jupiter < Proxima Centauri < Sun < Sirius
4. Sirius < Pollux < Arcturus < Aldebaran
5. Aldebaran < Rigel < Antares < Betelgeuse
6. Betelgeuse < Mu Cephei < VV Cephei A < VY Canis Majoris

Not pictured: NML Cygni, UY Scuti

UY Scuti as seen in visible light.

Below is a list of the largest stars so far discovered, ordered by radius. The unit of measurement used is the radius of the Sun (approximately 695,500 kilometers, or 432,450 miles).

The exact order of this list is not complete, nor is it perfectly defined:

• There are sometimes high uncertainties in derived values and sizes;
• The distances to most of these stars are uncertain to differing degrees and this uncertainty affects the size measurements;
• All the stars in this list have extended atmospheres, many are embedded in mostly opaque dust shells or disks, and most pulsate, such that their radii are not well defined;
• There are theoretical reasons for expecting that no stars in the Milky Way are larger than approximately 1,500 times the Sun, based on evolutionary models and the Hayashi instability zone. The exact limit depends on the metallicity of the star, so for example supergiants in the Magellanic Clouds have slightly different limiting temperature and luminosity. Stars exceeding the limit have been seen to undergo large eruptions and to change their spectral type over just a few months;
• A survey of the Magellanic Clouds has catalogued most of the red supergiants and 44 of them are larger than the 700 solar radii cutoff point of this table, with the largest at 1,200–1,300.^[1]

List

This list is incomplete; you can help by expanding it.

List of the largest stars

Star	Solar radii (Sun = 1)	Notes	Ref.
UY Scuti	1,708	Margin of error in size determination: ± 192 solar radii. At its smallest, its size would be similar to that of VX Sagittarii (see below).	[2]
NML Cygni	1,642–2,775	NML Cyg is a semiregular variable star surrounded by a circumstellar nebula and is heavily obscured by dust extinction.	[3]
WOH G64	1,540	This would be the largest star in the LMC, but is unusual in position and motion and might still be a foreground halo giant.	[4]
RW Cephei	1,535	RW Cep is variable both in brightness (by at least a factor of 3) and spectral type (observed from G8 to M), thus probably also in diameter. Because the spectral type and temperature at maximum luminosity are not known, the quoted size is just an estimate.	[5][6]
Westerlund 1-26	1,530	Very uncertain parameters for an unusual star with strong radio emission. The spectrum is variable but apparently the luminosity is not.	[7]
V354 Cephei	1,520		[8]
VX Sagittarii	1,520	VX Sgr is a pulsating variable with a large visual range and varies significantly in size.	[9]
VY Canis Majoris	1,420	Previously thought to be a star so large that it contradicted stellar evolutionary theory, a newly improved measurement has brought it down to size. Margin of possible error: ± 120 solar radii.	[10][11]
KY Cygni	1,420	KY Cygni is located in a region with heavy dust extinction, thus making it hard to determine its size. The quoted size is the value consistent with stellar evolutionary models, the true range may be larger.	[8]
AH Scorpii	1,411	AH Sco is variable by nearly 3 magnitudes in the visual range, and an estimated 20% in total luminosity. The variation in diameter is not clear because the temperature also varies.	[2]
HR 5171 A	1,316	HR 5171 A is a highly distorted star in a close binary system, losing mass to the secondary.	[12]
SMC 18136	1,310		[1]
PZ Cassiopeiae	1,260–1,340		[13]
Mu Cephei (Herschel's "Garnet Star")	1,260		[14]
KW Sagittarii	1,235		[2][8]
IRC-10414	1,200		[15]
EV Carinae	1,168		[16]
BC Cygni	1,140		[8]
RT Carinae	1,090		[8]
BI Cygni	1,078		[9][8]
Betelgeuse (Alpha Orionis)	955-1,200	Ninth brightest star in the night sky.	[17]
V396 Centauri	1,070		[8]
CK Carinae	1,060		[8]
VV Cephei A	1,050	VV Cep A is a highly distorted star in a binary system, losing mass to its B-type companion VV Cephei B for at least part of its orbit. Older estimates have given much larger sizes.	[18]
V602 Carinae	1,050		[19]
S Persei	1,005	In the Perseus Double Cluster.	[8]
RS Persei	1,000	In the Perseus Double Cluster.	[8]
NR Vulpeculae	980		[8]
RW Cygni	980		[8]
GCIRS 7	960		[20]
Antares A (Alpha Scorpii A)	883
Theta Muscae	878
V1749 Cygni	830		[8]
IX Carinae	790		[8]
SU Persei	780	In the Perseus Double Cluster	[8]
TV Geminorum	770		[8]
T Cephei	742
V382 Carinae	700	Yellow hypergiant, one of the rarest types of star.

The following well-known stars are listed for the purpose of comparison.

Star name	Solar radii (Sun = 1)	Notes	Ref.
V509 Cassiopeiae	650	Yellow hypergiant, one of the rarest types of a star.
TZ Cassiopeiae	645
CE Tauri ("Ruby Star")	601	Can be occulted by the Moon, allowing accurate determination of its apparent diameter.
V355 Cephei	535		[9][8]
R Leporis ("Hind's Crimson Star")	500	One of the largest carbon stars existent in the Milky Way.
Alpha Herculis (Ras Algethi)	460
Rho Cassiopeiae	450	A yellow hypergiant, one of the rarest types of a star.
Mira A (Omicron Ceti)	400	Prototype Mira variable
V838 Monocerotis	380	Once topped to the list as one of the largest stars, after experiencing a nova outburst it gradually decreased in size.
R Doradus	370	Star with the second largest apparent size after the Sun.
The Pistol Star	306	Blue hypergiant, currently among the most massive and luminous stars.
Eta Carinae A (Tseen She)	240	Previously thought to be the most massive single star, but in 2005 it was realized to be a binary system
S Doradus	240	Prototype S Doradus variable
La Superba (Y Canum Venaticorum)	215	Currently one of the coolest and reddest stars.
Deneb (Alpha Cygni)	203	19th brightest star in the night sky.
Peony Nebula Star	100	Candidate for most luminous star in the Milky Way.
Rigel A (Beta Orionis A)	78	Seventh brightest star in the night sky.
Canopus (Alpha Carinae)	65	Second brightest star in the night sky.
Aldebaran (Alpha Tauri)	44.2		[21]
R136a1	28.8	Also on the list as the most massive and luminous star.
HDE226868	21	The supergiant companion of black hole Cygnus X-1. The black hole is 500,000 times smaller than the star.

See also

• Constellation
• Lists of stars
• List of most massive stars
• List of most luminous stars
• List of hottest stars
• List of most massive black holes
• List of largest nebulae
• List of largest galaxies
• List of largest cosmic structures
• TrES-4b, one of the largest exoplanets

References

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External links

• Giant Stars An interactive website comparing the Earth and the Sun to some of the largest stars
• BBC News Three largest stars identified
• Universe Today What is the Biggest Star in the Universe?