List of largest stars
Below are lists of the largest stars currently known, ordered by radius and separated into categories by galaxy. The unit of measurement used is the radius of the Sun.
Overview
Although red supergiants are often considered the largest stars, some other star types have been found to temporarily increase significantly in radius, such as during LBV eruptions or luminous red novae. Luminous red novae appear to expand extremely rapidly, reaching thousands to tens of thousands of solar radii within only a few months, significantly larger than the largest red supergiants.Some studies use models that predict high-accreting Population III or Population I supermassive stars in the very early universe could have evolved "red supergiant protostars". These protostars are thought to have accretion rates larger than the rate of contraction, resulting in lower temperatures but with radii reaching up to many tens of thousands of, comparable to some of the largest known black holes.
Angular diameters
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 supergiants can be occulted by the Moon, including Antares and 119 Tauri. Examples of eclipsing binaries are Epsilon Aurigae, VV Cephei, and V766 Centauri. Angular diameter measurements can be inconsistent because the boundary of the very tenuous atmosphere differs depending on the wavelength of light in which the star is observed.Uncertainties remain with the membership and order of the lists, 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 these lists have inaccuracies and may be disputed. The lists are still a work in progress and parameters are prone to change.
Caveats
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:- Stellar radii or diameters are usually derived only approximately using the Stefan–Boltzmann law for the deduced stellar luminosity and effective surface temperature.
- Stellar distances, and their errors, for most stars, remain uncertain or poorly determined.
- Many extended supergiant atmospheres also significantly change in size over time, regularly or irregularly pulsating over several months or years as variable stars. This makes adopted luminosities poorly known and may significantly change the quoted radii.
- Other direct methods for determining stellar radii rely on lunar occultations or from eclipses in binary systems. This is only possible for a very small number of stars.
- Many distance estimates for red supergiants come from stellar cluster or association membership, because it is difficult to calculate accurate distances for red supergiants that are not part of any cluster or association.
- In these lists are some examples of extremely distant extragalactic stars, which may have slightly different properties and natures than the currently largest known stars in the Milky Way. For example, some red supergiants in the Magellanic Clouds are suspected to have slightly different limiting temperatures and luminosities. Such stars may exceed accepted limits by undergoing large eruptions or changing their spectral types over just a few months.
Lists
The following lists show the largest known stars based on the host galaxy.Outside the Virgo supercluster
Note that this list does not include the candidate JWST Dark [star (dark matter)|dark stars], with estimated radii of up to or quasi-stars, with theoretical models suggesting that they could reach radii of up to.Transient events
During some transient events, such as red novae or LBV eruptions the star's radius can increase by a significant amount.| Star or transient event name | Solar radii | Year | Galaxy | Group | Method | Notes |
| AT 2017jfs | >33,000 | 2017 | NGC 4470 | L/Teff | ||
| SNhunt151 | 2014 | UGC 3165 | LDC 331 | L/Teff | ||
| SN 2015bh | 2015 | NGC 2770 | LDC 616 | L/Teff | ||
| AT 2018hso | 10,350 | 2018 | NGC 3729 | M109 Group | L/Teff | |
| AT 2023clx | 2023 | NGC 3799 | nest 101314 | L/Teff | ||
| M51 OT2019-1 | 2019 | Whirlpool Galaxy | M51 Group | L/Teff | ||
| η Carinae | 4,319 – 6,032 | 1845 | Milky Way | Local Group | L/Teff | During the outburst, the star became the second brightest star in sky, reaching an apparent magnitude of between −0.8 and −1.0. |
| AT 2010dn | 2010 | NGC 3180 | LDC 743 | L/Teff | ||
| SN 2011fh | 3,980 | 2011 | NGC 4806 | Abell 3528 | L/Teff | |
| AT 2014ej | 2014 | NGC 7552 | Grus Quartet | L/Teff | ||
| V838 Monocerotis | 3,190 | 2002 | Milky Way | Local Group | L/Teff | |
| SN2008S | 2008 | NGC 6946 | NGC 6946 Group | L/Teff | ||
| SNhunt120 | 2012 | NGC 5775 | Virgo Cluster | L/Teff | ||
| AT 2017be | 2017 | NGC 2537 | L/Teff | |||
| PHL 293B star | 1,348 – 1,463 | 2002 | PHL 293B | L/Teff | ||
| SNhunt248 | ~850 | 2014 | NGC 5806 | NGC 5846 Group | L/Teff | |
| SN 2002kg | 704 | 2002 | NGC 2403 | M81 Group | L/Teff | |
| R71 | 500 | 2012 | Large Magellanic Cloud | Local Group | L/Teff | |
| SN 2000ch | 500 | 2000 | NGC 3432 | LDC 743 | L/Teff | |
| Godzilla | 430 – 2,365 | 2015 | Sunburst galaxy | L/Teff | ||
| AT 2016blu | ~330 | 2012 – 2022 | NGC 4559 | Coma I Group | L/Teff | 19 outbursts were detected between 2012 and 2022. The star was likely relatively stable the decade before since no outbursts were detected from 1999 – 2009. |
SN Progenitors
Largest stars by apparent size
The following list include the largest stars by their apparent size as seen from Earth. The unit of measurement is the milliarcsecond, equivalent to. Stars with angular diameters larger than 13milliarcseconds are included.| Name | Angular diameter type | Distance | Notes | ||
| Sun | 2,000,000 | 0.000016 | G2V | angular diameter. | |
| R Doradus | 51.18 | LD | 179 | M8III:e | angular diameter apart from the Sun. |
| Betelgeuse | 42.28 | LD | 408–540 | ||
| Antares | 37.31 | LD | 553.5 | M1.5Iab | |
| Mira | 28.934.9 | Ross | 299 | M5-M9IIIe | The angular diameter vary during Mira's pulsations. |
| Tiaki | 28.8 | ? | 177 | M4.5III | |
| Gacrux | 24.7 | ? | 88.6 | M3.5III | |
| Rasalgethi | 23.95 | Est | 359 | M5Ib-II | |
| R Hydrae | 23.7 | ? | 482 | M6-9e | |
| Arcturus | 21.06 | LD | 36.8 | K1.5IIIFe-0.5 | |
| π1 Gruis | 21 | ? | 535 | S5,7 | |
| Aldebaran | 20.58–21.1 | LD | 65.3 | K5+III | |
| GY Aquilae | 20.46 | ? | 1108 | M8 | |
| θ Apodis | 18.1 | ? | 389 | M6.5III | |
| R Lyrae | 18.016 | LD | 310 | M4.5III | |
| Scheat | 16.75 | Ross | 196 | M2.5II-III | |
| 16.555 | LD | 308 | M4+IIIa | ||
| SW Virginis | 16.11–16.8 | UD | 527 | M7III: | |
| R Aquarii | 15.6116.59 | LD | 711 | M6.5–M8.5e | |
| g Herculis | 15.219.09 | LD | 385 | M6-III | |
| RS Cancri | 15.117.2 | LD | 490 | M6S | |
| Tejat | 15.118 | LD | 230 | M3IIIab | |
| R Leonis Minoris | 14.4 | LD | 942 | M6.5-9e | |
| S Cephei | 14.29 | LD | 1591 | C7,3e | |
| T Cassiopeiae | 14.22 | LD | 893 | M7-9e | |
| μ Cephei | 14.11 ± 0.6 | 2,000–3060 | M2Ia | ||
| Mirach | 13.749 | LD | 199 | M0+IIIa | |
| Menkar | 13.238 | LD | 249 | M1.5IIIa | Other measurements include 12.2 mas. |
| V Cygni | 13.114.84 | LD | 1747 | C7,4eJ |